Re: [PSES] Adding more than one EUT

[Ken Javor]

The point about luminaries is that the radiation mechanism is going to be
almost wholly through the building wiring, and to the extent that you have
luminaries in every room of a building, the entire house wiring will be
radiating.

I don't believe the typical CISPR test set-up with maybe a 6' power cord
plugged into a LISN does justice to this radiation mechanism. I don't know
if the luminary radiated emission test method and/or conducted emission
limit takes any of this into account, although John Woodgate, in his
inimitable way, stated that the emission limit for luminaries is stricter
than for less ubiquitously used products.

Ken Javor
Phone: (256) 650-5261



> From: "T.Sato" 
> Reply-To: "T.Sato" 
> Date: Sun, 19 Feb 2023 14:03:21 +0900
> To: 
> Subject: Re: [PSES] Adding more than one EUT
> 
> On Sat, 18 Feb 2023 19:12:57 +0900,
>   "T.Sato"  wrote:
> ...
>> However, in case of the EMC Directive, it requires "... it complies
>> with this Directive when properly installed, maintained and used for
>> its intended purpose."
>> 
>> If if is considered that to install tens of LED lights in a house is
>> covered by the "intended purpose", shouldn't the LED lights still
>> comply with the essential requirements of the Directive in that
>> configuration, too?
> 
> P.S.
> 
> I didn't mean to test tens or hundreds of lamps as a whole.
> 
> I only said that they shouldn't cause interference poblem (it is half
> of the essential requirements of the Directive) when installed and used
> as intended.
> 
> Regards,
> Tom
> 
> 
>>> On Fri, Feb 17, 2023 at 6:56 PM Ken Javor 
>>> wrote:
>>> 
>>>> I¹m finding this an extremely interesting discussion. I don¹t have
>>>> anything definitive to offer, but I do have a question to help stir the
>>>> pot.
>>>> 
>>>> If the possibility that multiple items might be used together and that
>>>> emissions will be additive in some fashion is a justification for testing
>>>> multiple units at a time, what about ... light bulbs?
>>>> 
>>>> Meaning CFLs or LEDs.
>>>> 
>>>> My house is full of them.  It is reasonable to assume that most
>>>> homes/businesses are. Perhaps the emissions limits for these were based on
>>>> this reasonably foreseeable outcome?
>>>> 
>>>> Ken Javor
>>>> Phone: (256) 650-5261
>>>> 
>>>> 
>>>> --
>>>> *From: *John Mcbain 
>>>> *Reply-To: *John Mcbain 
>>>> *Date: *Fri, 17 Feb 2023 14:22:44 -0800
>>>> *To: *
>>>> *Subject: *Re: [PSES] Adding more than one EUT
>>>> 
>>>> Hi Derek -
>>>> 
>>>> Typical requirement for a unit that may be sold and used in multiples
>>>> (that is, all the units can be sold together as one product) is you can
>>>> test just one IF adding the other units does not increase the emissions.
>>>> 
>>>> Of course the most practical way to determine that is to assemble the
>>>> multiple units to see what happens.  If the test result for testing max.
>>>> connected units compared to testing only one unit shows no significant
>>>> difference, then you're good - but definitely archive those test results!
>>>> 
>>>> If you can't pass the test with all units connected, then whatever you do,
>>>> don't let Marketing create a multiple-unit product to sell.  ;-)
>>>> 
>>>> Similarly, the desktop PC system that James mentioned would have all power
>>>> cords separately tested for conducted emissions as a fully connected system
>>>> (monitor, printer, scanner, etc. attached) if it is a  product sold as a
>>>> complete all-included system.
>>>> 
>>>> Best regards,
>>>> John McBain
>>>> 
>>>> 
>>>> On Fri, Feb 17, 2023 at 1:59 PM James Pawson (U3C) <
>>>> ja...@unit3compliance.co.uk> wrote:
>>>> 
>>>> 
>>>> Hi Derek,
>>>> 
>>>> 
>>>> Is the daisy chain connection the AC supply or some other power bus?
>>>> 
>>>> 
>>>> How is 8 units daisy chained any different to 8 separate units all on the
>>>> same power bus? We are looking for individual emission contributions from
>>>> each connected unit.
>>>> 
>>>> 
>>>> If measuring conducted emissions on a desktop pc (y'

Re: [PSES] Adding more than one EUT

[Charlie Blackham]

Derek

The EMC Directive requires the manufacturer to perform an "an adequate analysis 
and assessment of the risk(s)." (Annex II, module A, para 3)

That risk assessment has to consider foreseeable use.

It's for the manufacturer to decide, but if I was advising them, then I would 
suggest that maybe testing 3 combinations would cover it:
- minimum number of supported lights
- maximum number
- approx. 50% load

So, in this example, 1, 8 and 4 or 5.

Ultimately though, It's the manufacturer's responsibility to make the call.

Best regards
Charlie

Charlie Blackham
Sulis Consultants Ltd
Tel: +44 (0)7946 624317
Web: https://sulisconsultants.com/ 
Registered in England and Wales, number 05466247

-Original Message-
From: Lfresearch <00734758d943-dmarc-requ...@listserv.ieee.org> 
Sent: 17 February 2023 20:21
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Adding more than one EUT

Hi folks,

I’ve been asked to test a light fixture that has the ability to be daisy 
chained up to 8 units.

When I run conducted emissions, I’m wondering if I need to insist on having 8 
units plugged in at once i.e. fully populated, OR, can I just test one fixture 
at a time since that’s how the system is likely to be used also..

Is there a legal requirement or precedent on how this should be tested as I’m 
going round in circles arguing with myself here.

Thanks,

Derek.

SSCLabs,
Reno, NV.
-

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Re: [PSES] Adding more than one EUT

[T.Sato]

On Sat, 18 Feb 2023 19:12:57 +0900,
  "T.Sato"  wrote:
...
> However, in case of the EMC Directive, it requires "... it complies
> with this Directive when properly installed, maintained and used for
> its intended purpose."
> 
> If if is considered that to install tens of LED lights in a house is
> covered by the "intended purpose", shouldn't the LED lights still
> comply with the essential requirements of the Directive in that
> configuration, too?

P.S.

I didn't mean to test tens or hundreds of lamps as a whole.

I only said that they shouldn't cause interference poblem (it is half
of the essential requirements of the Directive) when installed and used
as intended.

Regards,
Tom


>> On Fri, Feb 17, 2023 at 6:56 PM Ken Javor 
>> wrote:
>> 
>>> I’m finding this an extremely interesting discussion. I don’t have
>>> anything definitive to offer, but I do have a question to help stir the pot.
>>>
>>> If the possibility that multiple items might be used together and that
>>> emissions will be additive in some fashion is a justification for testing
>>> multiple units at a time, what about ... light bulbs?
>>>
>>> Meaning CFLs or LEDs.
>>>
>>> My house is full of them.  It is reasonable to assume that most
>>> homes/businesses are. Perhaps the emissions limits for these were based on
>>> this reasonably foreseeable outcome?
>>>
>>> Ken Javor
>>> Phone: (256) 650-5261
>>>
>>>
>>> --
>>> *From: *John Mcbain 
>>> *Reply-To: *John Mcbain 
>>> *Date: *Fri, 17 Feb 2023 14:22:44 -0800
>>> *To: *
>>> *Subject: *Re: [PSES] Adding more than one EUT
>>>
>>> Hi Derek -
>>>
>>> Typical requirement for a unit that may be sold and used in multiples
>>> (that is, all the units can be sold together as one product) is you can
>>> test just one IF adding the other units does not increase the emissions.
>>>
>>> Of course the most practical way to determine that is to assemble the
>>> multiple units to see what happens.  If the test result for testing max.
>>> connected units compared to testing only one unit shows no significant
>>> difference, then you're good - but definitely archive those test results!
>>>
>>> If you can't pass the test with all units connected, then whatever you do,
>>> don't let Marketing create a multiple-unit product to sell.  ;-)
>>>
>>> Similarly, the desktop PC system that James mentioned would have all power
>>> cords separately tested for conducted emissions as a fully connected system
>>> (monitor, printer, scanner, etc. attached) if it is a  product sold as a
>>> complete all-included system.
>>>
>>> Best regards,
>>> John McBain
>>>
>>>
>>> On Fri, Feb 17, 2023 at 1:59 PM James Pawson (U3C) <
>>> ja...@unit3compliance.co.uk> wrote:
>>>
>>>
>>> Hi Derek,
>>>
>>>
>>> Is the daisy chain connection the AC supply or some other power bus?
>>>
>>>
>>> How is 8 units daisy chained any different to 8 separate units all on the
>>> same power bus? We are looking for individual emission contributions from
>>> each connected unit.
>>>
>>>
>>> If measuring conducted emissions on a desktop pc (y'know, the big ones we
>>> had before everyone had laptops to work from home...) the you would just
>>> measure the PC, not the monitor and printer and scanner and modem and and
>>> and...
>>>
>>>
>>> Just thinking aloud
>>>
>>> All the best
>>>
>>> James
>>>
>>>
>>>  Lfresearch wrote 
>>>
>>> Hi folks,
>>>
>>>
>>>
>>> I’ve been asked to test a light fixture that has the ability to be daisy
>>> chained up to 8 units.
>>>
>>>
>>>
>>> When I run conducted emissions, I’m wondering if I need to insist on
>>> having 8 units plugged in at once i.e. fully populated, OR, can I just test
>>> one fixture at a time since that’s how the system is likely to be used
>>> also..
>>>
>>>
>>>
>>> Is there a legal requirement or precedent on how this should be tested as
>>> I’m going round in circles arguing with myself here.
>>>
>>>
>>>
>>> Thanks,
>>>
>>>
>>>
>>> Derek.
>&

Re: [PSES] Adding more than one EUT

[John Mcbain]

Hi Tom -

Right - if the installer installs the product NOT according to directions,
then any interference is his problem. But if the installation is done
according to the manufacturer's instructions and causes interference, then
it is likely the manufacturer will bear some or all responsibility.

Of course, the installer/user still will be asked to cease operation if the
interference is causing a problem. The argument "The manufacturer said it
was OK!" will not convince authorities to allow operation to continue if
there is a significant problem.

Best regards,
John McBain


On Sat, Feb 18, 2023 at 6:14 PM T.Sato  wrote:

> On Sat, 18 Feb 2023 11:07:01 -0800,
>   John Mcbain  wrote:
>
> > Absolutely, the requirement is "... it complies with this Directive when
> > properly installed, maintained and used for its intended purpose."  But
> > what is "it"?
> >
> > I maintain that "it" is the product that is tested and sold, not all the
> > possible final configurations in which combinations of "it" might be
> > found.
>
> Assume a product that is clearly intended to be installed and used with
> tens of the same model of the product.
> If the product is installed and used as intended and caused interference,
> although with other tens of same model of the product, isn't it caused
> the interference?
>
> > The final installer/user, not the manufacturer, would be responsible for
> > whatever interference might be caused by the in-use combination of
> multiple
> > units of compliant products UNLESS the manufacturer sells that
> combination
> > as a product.
>
> The EMC Directive require to provide instruction neessary to comply
> with the essential requirements.
>
> If installer didn't follow the provided instruction and caused
> interference problem, I think the installer is responsible.
>
> However, if the installer follow the provided instruction if any
> (and electric code, if applicable) but still caused interference
> problem, the installer (maybe end-user himself, who is probably layman
> at least for EMC) still responsible for that?
>
> Regards,
> Tom
>
>
> > On Sat, Feb 18, 2023 at 2:13 AM T.Sato  wrote:
> >
> >> On Fri, 17 Feb 2023 21:12:40 -0800,
> >>   John Mcbain  wrote:
> >>
> >> > The key is testing the .  If all the light bulbs in your
> house
> >> and
> >> > the connecting wiring was sold as a single product, then presumably it
> >> > would have been tested for EMC in that configuration.  I doubt that is
> >> what
> >> > happened.  
> >>
> >> Well, standards usually require to test product, in a representative
> >> or minimum configuration.
> >>
> >> However, in case of the EMC Directive, it requires "... it complies
> >> with this Directive when properly installed, maintained and used for
> >> its intended purpose."
> >>
> >> If if is considered that to install tens of LED lights in a house is
> >> covered by the "intended purpose", shouldn't the LED lights still
> >> comply with the essential requirements of the Directive in that
> >> configuration, too?
> >>
> >> Regards,
> >> Tom
> >>
> >>
> >> > On Fri, Feb 17, 2023 at 6:56 PM Ken Javor <
> ken.ja...@emccompliance.com>
> >> > wrote:
> >> >
> >> >> I’m finding this an extremely interesting discussion. I don’t have
> >> >> anything definitive to offer, but I do have a question to help stir
> the
> >> pot.
> >> >>
> >> >> If the possibility that multiple items might be used together and
> that
> >> >> emissions will be additive in some fashion is a justification for
> >> testing
> >> >> multiple units at a time, what about ... light bulbs?
> >> >>
> >> >> Meaning CFLs or LEDs.
> >> >>
> >> >> My house is full of them.  It is reasonable to assume that most
> >> >> homes/businesses are. Perhaps the emissions limits for these were
> based
> >> on
> >> >> this reasonably foreseeable outcome?
> >> >>
> >> >> Ken Javor
> >> >> Phone: (256) 650-5261
> >> >>
> >> >>
> >> >> --
> >> >> *From: *John Mcbain 
> >> >> *Reply-To: *John Mcbain 
> >> >> *Date: *Fri, 17 Feb 2023 14:22:44 -0800
> >> >> *To: *
> >> >> *Subject: *Re: [PSES]

Re: [PSES] Adding more than one EUT

[T.Sato]

On Sat, 18 Feb 2023 11:07:01 -0800,
  John Mcbain  wrote:

> Absolutely, the requirement is "... it complies with this Directive when
> properly installed, maintained and used for its intended purpose."  But
> what is "it"?
> 
> I maintain that "it" is the product that is tested and sold, not all the
> possible final configurations in which combinations of "it" might be
> found.

Assume a product that is clearly intended to be installed and used with
tens of the same model of the product.
If the product is installed and used as intended and caused interference,
although with other tens of same model of the product, isn't it caused
the interference?

> The final installer/user, not the manufacturer, would be responsible for
> whatever interference might be caused by the in-use combination of multiple
> units of compliant products UNLESS the manufacturer sells that combination
> as a product.

The EMC Directive require to provide instruction neessary to comply
with the essential requirements.

If installer didn't follow the provided instruction and caused
interference problem, I think the installer is responsible.

However, if the installer follow the provided instruction if any
(and electric code, if applicable) but still caused interference
problem, the installer (maybe end-user himself, who is probably layman
at least for EMC) still responsible for that?

Regards,
Tom


> On Sat, Feb 18, 2023 at 2:13 AM T.Sato  wrote:
> 
>> On Fri, 17 Feb 2023 21:12:40 -0800,
>>   John Mcbain  wrote:
>>
>> > The key is testing the .  If all the light bulbs in your house
>> and
>> > the connecting wiring was sold as a single product, then presumably it
>> > would have been tested for EMC in that configuration.  I doubt that is
>> what
>> > happened.  
>>
>> Well, standards usually require to test product, in a representative
>> or minimum configuration.
>>
>> However, in case of the EMC Directive, it requires "... it complies
>> with this Directive when properly installed, maintained and used for
>> its intended purpose."
>>
>> If if is considered that to install tens of LED lights in a house is
>> covered by the "intended purpose", shouldn't the LED lights still
>> comply with the essential requirements of the Directive in that
>> configuration, too?
>>
>> Regards,
>> Tom
>>
>>
>> > On Fri, Feb 17, 2023 at 6:56 PM Ken Javor 
>> > wrote:
>> >
>> >> I’m finding this an extremely interesting discussion. I don’t have
>> >> anything definitive to offer, but I do have a question to help stir the
>> pot.
>> >>
>> >> If the possibility that multiple items might be used together and that
>> >> emissions will be additive in some fashion is a justification for
>> testing
>> >> multiple units at a time, what about ... light bulbs?
>> >>
>> >> Meaning CFLs or LEDs.
>> >>
>> >> My house is full of them.  It is reasonable to assume that most
>> >> homes/businesses are. Perhaps the emissions limits for these were based
>> on
>> >> this reasonably foreseeable outcome?
>> >>
>> >> Ken Javor
>> >> Phone: (256) 650-5261
>> >>
>> >>
>> >> --
>> >> *From: *John Mcbain 
>> >> *Reply-To: *John Mcbain 
>> >> *Date: *Fri, 17 Feb 2023 14:22:44 -0800
>> >> *To: *
>> >> *Subject: *Re: [PSES] Adding more than one EUT
>> >>
>> >> Hi Derek -
>> >>
>> >> Typical requirement for a unit that may be sold and used in multiples
>> >> (that is, all the units can be sold together as one product) is you can
>> >> test just one IF adding the other units does not increase the emissions.
>> >>
>> >> Of course the most practical way to determine that is to assemble the
>> >> multiple units to see what happens.  If the test result for testing max.
>> >> connected units compared to testing only one unit shows no significant
>> >> difference, then you're good - but definitely archive those test
>> results!
>> >>
>> >> If you can't pass the test with all units connected, then whatever you
>> do,
>> >> don't let Marketing create a multiple-unit product to sell.  ;-)
>> >>
>> >> Similarly, the desktop PC system that James mentioned would have all
>> power
>> >> cords separately tested for conducted emissions as a fully connected
>> system

Re: [PSES] Adding more than one EUT

[Brent DeWitt]

I'm being a bit flippant, but;

- If I was in my 3rd-party test house role, it stops when the customer 
says stop.
- If I am the steward of my company's product, it stops when my 
"engineering judgement" says we've "done our best to find the worst". 


Assuming, of course, that it's a DoC product for the US and EU.

Brent

On 2/18/2023 3:51 PM, Dan Roman wrote:


Back in a previous life when I worked on PCIe, VME, etc. boards that 
plugged into a chassis, we would frequently start adding cards until 
we saw no increase in emissions to satisfy compliance if a customer 
used multiples of our boards, which was often the case.  These were 
components however and to me it seems a bit murkier if an end product 
that could function standalone is used with others, especially if each 
has its own power cord.


Even in my case with the PC cards, we didn’t test multiples of every 
combination of boards we sold, it would be impossible to do.  Does the 
manufacturer of an LED light bulb need to test just one bulb or do 
they need to find the fixture that holds the most lightbulbs and test 
in that?  I don’t think so much in the same way that a server 
manufacturer tests one server and doesn’t need to find the customer 
that puts the most servers in a rack or a computer room and test that 
number of servers.  Perhaps if they are selling a rack of servers that 
uses a common power cord?


Where does it stop?

Dan

*From:*John Mcbain [mailto:johnmcb...@ieee.org]
*Sent:* Saturday, February 18, 2023 2:20 PM
*To:* EMC-PSTC@LISTSERV.IEEE.ORG
*Subject:* Re: [PSES] Adding more than one EUT

Hi Brent -

Yes, different testing certainly would be appropriate for different 
power distribution and connection methods, so knowing ALL the details 
is very important to decide how to test.


However, one _essential_ piece of knowledge may be overlooked.  What 
exactly is the product being sold?  Marketing plays a _huge_ role in 
knowing what to test, and decisions made by Marketing AFTER the 
product is released can create non-compliant products without a single 
physical change being made. Common case - let's sell this new 
combination of equipment as a single product.


And of course, since "no changes are being made to the product" 
(wrong!) why bother telling the compliance engineer?  Been there!



Best regards,

John McBain

On Sat, Feb 18, 2023 at 7:37 AM Brent DeWitt  
wrote:


An unanswered, and critical, question is:
Do the "daisy-chained" devices draw power produced by the initial
item, or do they all have independent power supplies?

- First case: Initial unit produces DC/AC for the additional units.
- Second case: the initial unit is a simple, passive "power strip"
for the additional units.

In the first case, I would expect testing as a system, with all
units attached
In the second case, I would test a single unit.

Another implication is for radiated emissions. What is the
expected spacing between units in the typical users.

with respect,

Brent DeWitt
Milford, MA

On 2/17/2023 9:56 PM, Ken Javor wrote:

I’m finding this an extremely interesting discussion. I don’t
have anything definitive to offer, but I do have a question to
help stir the pot.

If the possibility that multiple items might be used together
and that emissions will be additive in some fashion is a
justification for testing multiple units at a time, what about
... light bulbs?

Meaning CFLs or LEDs.

My house is full of them.  It is reasonable to assume that
most homes/businesses are. Perhaps the emissions limits for
these were based on this reasonably foreseeable outcome?

Ken Javor
Phone: (256) 650-5261



*From: *John Mcbain http://johnmcb...@ieee.org>>
*Reply-To: *John Mcbain http://johnmcb...@ieee.org>>
*Date: *Fri, 17 Feb 2023 14:22:44 -0800
    *To: *http://EMC-PSTC@LISTSERV.IEEE.ORG>>
*Subject: *Re: [PSES] Adding more than one EUT

Hi Derek -

Typical requirement for a unit that may be sold and used in
multiples (that is, all the units can be sold together as one
product) is you can test just one IFadding the other units
does not increase the emissions.

Of course the most practical way to determine that is to
assemble the multiple units to see what happens.  If the test
result for testing max. connected units compared to testing
only one unit shows no significant difference, then you're
good - but definitely archive those test results!

If you can't pass the test with all units connected, then
whatever you do, don't let Marketing create a multiple-unit
product to sell.  ;-)

Similarly, the

Re: [PSES] Adding more than one EUT

[Dan Roman]

Back in a previous life when I worked on PCIe, VME, etc. boards that plugged 
into a chassis, we would frequently start adding cards until we saw no increase 
in emissions to satisfy compliance if a customer used multiples of our boards, 
which was often the case.  These were components however and to me it seems a 
bit murkier if an end product that could function standalone is used with 
others, especially if each has its own power cord.

 

Even in my case with the PC cards, we didn’t test multiples of every 
combination of boards we sold, it would be impossible to do.  Does the 
manufacturer of an LED light bulb need to test just one bulb or do they need to 
find the fixture that holds the most lightbulbs and test in that?  I don’t 
think so much in the same way that a server manufacturer tests one server and 
doesn’t need to find the customer that puts the most servers in a rack or a 
computer room and test that number of servers.  Perhaps if they are selling a 
rack of servers that uses a common power cord?

 

Where does it stop?

 

Dan

 

 

From: John Mcbain [mailto:johnmcb...@ieee.org] 
Sent: Saturday, February 18, 2023 2:20 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Adding more than one EUT

 

Hi Brent -

 

Yes, different testing certainly would be appropriate for different power 
distribution and connection methods, so knowing ALL the details is very 
important to decide how to test.

 

However, one essential piece of knowledge may be overlooked.  What exactly is 
the product being sold?  Marketing plays a huge role in knowing what to test, 
and decisions made by Marketing AFTER the product is released can create 
non-compliant products without a single physical change being made.  Common 
case - let's sell this new combination of equipment as a single product.

 

And of course, since "no changes are being made to the product" (wrong!) why 
bother telling the compliance engineer?  Been there!




Best regards,

John McBain

 

 

On Sat, Feb 18, 2023 at 7:37 AM Brent DeWitt mailto:bdew...@ix.netcom.com> > wrote:

An unanswered, and critical, question is:
Do the "daisy-chained" devices draw power produced by the initial item, or do 
they all have independent power supplies?

- First case: Initial unit produces DC/AC for the additional units.
- Second case: the initial unit is a simple, passive "power strip" for the 
additional units.

In the first case, I would expect testing as a system, with all units attached
In the second case, I would test a single unit.

Another implication is for radiated emissions. What is the expected spacing 
between units in the typical users.

with respect,

Brent DeWitt
Milford, MA

On 2/17/2023 9:56 PM, Ken Javor wrote:

I’m finding this an extremely interesting discussion. I don’t have anything 
definitive to offer, but I do have a question to help stir the pot.

If the possibility that multiple items might be used together and that 
emissions will be additive in some fashion is a justification for testing 
multiple units at a time, what about ... light bulbs? 

Meaning CFLs or LEDs. 

My house is full of them.  It is reasonable to assume that most 
homes/businesses are. Perhaps the emissions limits for these were based on this 
reasonably foreseeable outcome?

Ken Javor
Phone: (256) 650-5261




  _  


From: John Mcbain < <http://johnmcb...@ieee.org> johnmcb...@ieee.org>
Reply-To: John Mcbain < <http://johnmcb...@ieee.org> johnmcb...@ieee.org>
Date: Fri, 17 Feb 2023 14:22:44 -0800
To: < <http://EMC-PSTC@LISTSERV.IEEE.ORG> EMC-PSTC@LISTSERV.IEEE.ORG>
Subject: Re: [PSES] Adding more than one EUT

Hi Derek -

Typical requirement for a unit that may be sold and used in multiples (that is, 
all the units can be sold together as one product) is you can test just one IF 
adding the other units does not increase the emissions.

Of course the most practical way to determine that is to assemble the multiple 
units to see what happens.  If the test result for testing max. connected units 
compared to testing only one unit shows no significant difference, then you're 
good - but definitely archive those test results!

If you can't pass the test with all units connected, then whatever you do, 
don't let Marketing create a multiple-unit product to sell.  ;-)

Similarly, the desktop PC system that James mentioned would have all power 
cords separately tested for conducted emissions as a fully connected system 
(monitor, printer, scanner, etc. attached) if it is a  product sold as a 
complete all-included system.

Best regards,
John McBain


On Fri, Feb 17, 2023 at 1:59 PM James Pawson (U3C) < 
<http://ja...@unit3compliance.co.uk> ja...@unit3compliance.co.uk> wrote:


Hi Derek,


Is the daisy chain connection the AC supply or some other power bus?


How is 8 units daisy chained any different to 8 separate units all on the same 
power bus? We are looking for individual 

Re: [PSES] Adding more than one EUT

[John Mcbain]

Hi Brent -

Yes, different testing certainly would be appropriate for different power
distribution and connection methods, so knowing ALL the details is very
important to decide how to test.

However, one *essential* piece of knowledge may be overlooked.  What
exactly is the product being sold?  Marketing plays a *huge* role in
knowing what to test, and decisions made by Marketing AFTER the product is
released can create non-compliant products without a single physical change
being made.  Common case - let's sell this new combination of equipment as
a single product.

And of course, since "no changes are being made to the product" (wrong!)
why bother telling the compliance engineer?  Been there!

Best regards,
John McBain


On Sat, Feb 18, 2023 at 7:37 AM Brent DeWitt  wrote:

> An unanswered, and critical, question is:
> Do the "daisy-chained" devices draw power produced by the initial item, or
> do they all have independent power supplies?
>
> - First case: Initial unit produces DC/AC for the additional units.
> - Second case: the initial unit is a simple, passive "power strip" for the
> additional units.
>
> In the first case, I would expect testing as a system, with all units
> attached
> In the second case, I would test a single unit.
>
> Another implication is for radiated emissions. What is the expected
> spacing between units in the typical users.
>
> with respect,
>
> Brent DeWitt
> Milford, MA
>
> On 2/17/2023 9:56 PM, Ken Javor wrote:
>
> I’m finding this an extremely interesting discussion. I don’t have
> anything definitive to offer, but I do have a question to help stir the pot.
>
> If the possibility that multiple items might be used together and that
> emissions will be additive in some fashion is a justification for testing
> multiple units at a time, what about ... light bulbs?
>
> Meaning CFLs or LEDs.
>
> My house is full of them.  It is reasonable to assume that most
> homes/businesses are. Perhaps the emissions limits for these were based on
> this reasonably foreseeable outcome?
>
> Ken Javor
> Phone: (256) 650-5261
>
>
> --------------
> *From: *John Mcbain 
> *Reply-To: *John Mcbain 
> *Date: *Fri, 17 Feb 2023 14:22:44 -0800
> *To: *
> *Subject: *Re: [PSES] Adding more than one EUT
>
> Hi Derek -
>
> Typical requirement for a unit that may be sold and used in multiples
> (that is, all the units can be sold together as one product) is you can
> test just one IF adding the other units does not increase the emissions.
>
> Of course the most practical way to determine that is to assemble the
> multiple units to see what happens.  If the test result for testing max.
> connected units compared to testing only one unit shows no significant
> difference, then you're good - but definitely archive those test results!
>
> If you can't pass the test with all units connected, then whatever you do,
> don't let Marketing create a multiple-unit product to sell.  ;-)
>
> Similarly, the desktop PC system that James mentioned would have all power
> cords separately tested for conducted emissions as a fully connected system
> (monitor, printer, scanner, etc. attached) if it is a  product sold as a
> complete all-included system.
>
> Best regards,
> John McBain
>
>
> On Fri, Feb 17, 2023 at 1:59 PM James Pawson (U3C) <
> ja...@unit3compliance.co.uk> wrote:
>
>
> Hi Derek,
>
>
> Is the daisy chain connection the AC supply or some other power bus?
>
>
> How is 8 units daisy chained any different to 8 separate units all on the
> same power bus? We are looking for individual emission contributions from
> each connected unit.
>
>
> If measuring conducted emissions on a desktop pc (y'know, the big ones we
> had before everyone had laptops to work from home...) the you would just
> measure the PC, not the monitor and printer and scanner and modem and and
> and...
>
>
> Just thinking aloud
>
> All the best
>
> James
>
>
>  Lfresearch wrote 
>
> Hi folks,
>
>
>
> I’ve been asked to test a light fixture that has the ability to be daisy
> chained up to 8 units.
>
>
>
> When I run conducted emissions, I’m wondering if I need to insist on
> having 8 units plugged in at once i.e. fully populated, OR, can I just test
> one fixture at a time since that’s how the system is likely to be used
> also..
>
>
>
> Is there a legal requirement or precedent on how this should be tested as
> I’m going round in circles arguing with myself here.
>
>
>
> Thanks,
>
>
>
> Derek.
>
>
>
> SSCLabs,
>
> Reno, NV.
>
> -
>
> 

Re: [PSES] Adding more than one EUT

[John Mcbain]

Hi Tom -

Absolutely, the requirement is "... it complies with this Directive when
properly installed, maintained and used for its intended purpose."  But
what is "it"?

I maintain that "it" is the product that is tested and sold, not all the
possible final configurations in which combinations of "it" might be
found.

The final installer/user, not the manufacturer, would be responsible for
whatever interference might be caused by the in-use combination of multiple
units of compliant products UNLESS the manufacturer sells that combination
as a product.

As an analogy, consider acoustics.  There are regulations and standards for
testing allowable sound levels.  A single product may easily test under the
limit, but if multiple products are installed in a small room, the noise
could be much louder and even exceed permissible levels.  The manufacturer
would not be responsible UNLESS that installation was required or
recommended by the manufacturer.

Best regards,
John McBain


On Sat, Feb 18, 2023 at 2:13 AM T.Sato  wrote:

> On Fri, 17 Feb 2023 21:12:40 -0800,
>   John Mcbain  wrote:
>
> > The key is testing the .  If all the light bulbs in your house
> and
> > the connecting wiring was sold as a single product, then presumably it
> > would have been tested for EMC in that configuration.  I doubt that is
> what
> > happened.  
>
> Well, standards usually require to test product, in a representative
> or minimum configuration.
>
> However, in case of the EMC Directive, it requires "... it complies
> with this Directive when properly installed, maintained and used for
> its intended purpose."
>
> If if is considered that to install tens of LED lights in a house is
> covered by the "intended purpose", shouldn't the LED lights still
> comply with the essential requirements of the Directive in that
> configuration, too?
>
> Regards,
> Tom
>
>
> > On Fri, Feb 17, 2023 at 6:56 PM Ken Javor 
> > wrote:
> >
> >> I’m finding this an extremely interesting discussion. I don’t have
> >> anything definitive to offer, but I do have a question to help stir the
> pot.
> >>
> >> If the possibility that multiple items might be used together and that
> >> emissions will be additive in some fashion is a justification for
> testing
> >> multiple units at a time, what about ... light bulbs?
> >>
> >> Meaning CFLs or LEDs.
> >>
> >> My house is full of them.  It is reasonable to assume that most
> >> homes/businesses are. Perhaps the emissions limits for these were based
> on
> >> this reasonably foreseeable outcome?
> >>
> >> Ken Javor
> >> Phone: (256) 650-5261
> >>
> >>
> >> --
> >> *From: *John Mcbain 
> >> *Reply-To: *John Mcbain 
> >> *Date: *Fri, 17 Feb 2023 14:22:44 -0800
> >> *To: *
> >> *Subject: *Re: [PSES] Adding more than one EUT
> >>
> >> Hi Derek -
> >>
> >> Typical requirement for a unit that may be sold and used in multiples
> >> (that is, all the units can be sold together as one product) is you can
> >> test just one IF adding the other units does not increase the emissions.
> >>
> >> Of course the most practical way to determine that is to assemble the
> >> multiple units to see what happens.  If the test result for testing max.
> >> connected units compared to testing only one unit shows no significant
> >> difference, then you're good - but definitely archive those test
> results!
> >>
> >> If you can't pass the test with all units connected, then whatever you
> do,
> >> don't let Marketing create a multiple-unit product to sell.  ;-)
> >>
> >> Similarly, the desktop PC system that James mentioned would have all
> power
> >> cords separately tested for conducted emissions as a fully connected
> system
> >> (monitor, printer, scanner, etc. attached) if it is a  product sold as a
> >> complete all-included system.
> >>
> >> Best regards,
> >> John McBain
> >>
> >>
> >> On Fri, Feb 17, 2023 at 1:59 PM James Pawson (U3C) <
> >> ja...@unit3compliance.co.uk> wrote:
> >>
> >>
> >> Hi Derek,
> >>
> >>
> >> Is the daisy chain connection the AC supply or some other power bus?
> >>
> >>
> >> How is 8 units daisy chained any different to 8 separate units all on
> the
> >> same power bus? We are looking for individual emission contributions
> from
> >> each connected

Re: [PSES] Adding more than one EUT

[Brent DeWitt]

An unanswered, and critical, question is:
Do the "daisy-chained" devices draw power produced by the initial item, 
or do they all have independent power supplies?


- First case: Initial unit produces DC/AC for the additional units.
- Second case: the initial unit is a simple, passive "power strip" for 
the additional units.


In the first case, I would expect testing as a system, with all units 
attached

In the second case, I would test a single unit.

Another implication is for radiated emissions. What is the expected 
spacing between units in the typical users.


with respect,

Brent DeWitt
Milford, MA

On 2/17/2023 9:56 PM, Ken Javor wrote:
Re: [PSES] Adding more than one EUT I’m finding this an extremely 
interesting discussion. I don’t have anything definitive to offer, but 
I do have a question to help stir the pot.


If the possibility that multiple items might be used together and that 
emissions will be additive in some fashion is a justification for 
testing multiple units at a time, what about ... light bulbs?


Meaning CFLs or LEDs.

My house is full of them.  It is reasonable to assume that most 
homes/businesses are. Perhaps the emissions limits for these were 
based on this reasonably foreseeable outcome?


Ken Javor
Phone: (256) 650-5261



*From: *John Mcbain 
*Reply-To: *John Mcbain 
*Date: *Fri, 17 Feb 2023 14:22:44 -0800
*To: *
*Subject: *Re: [PSES] Adding more than one EUT

Hi Derek -

Typical requirement for a unit that may be sold and used in multiples 
(that is, all the units can be sold together as one product) is you 
can test just one IFadding the other units does not increase the 
emissions.


Of course the most practical way to determine that is to assemble the 
multiple units to see what happens.  If the test result for testing 
max. connected units compared to testing only one unit shows no 
significant difference, then you're good - but definitely archive 
those test results!


If you can't pass the test with all units connected, then whatever you 
do, don't let Marketing create a multiple-unit product to sell.  ;-)


Similarly, the desktop PC system that James mentioned would have all 
power cords separately tested for conducted emissions as a fully 
connected system (monitor, printer, scanner, etc. attached) if it is 
a  product sold as a complete all-included system.


Best regards,
John McBain


On Fri, Feb 17, 2023 at 1:59 PM James Pawson (U3C) 
 wrote:



Hi Derek,


Is the daisy chain connection the AC supply or some other power bus?


How is 8 units daisy chained any different to 8 separate units all
on the same power bus? We are looking for individual emission
contributions from each connected unit.


If measuring conducted emissions on a desktop pc (y'know, the big
ones we had before everyone had laptops to work from home...) the
you would just measure the PC, not the monitor and printer and
scanner and modem and and and...


Just thinking aloud

All the best

James


 Lfresearch wrote 

Hi folks,



I’ve been asked to test a light fixture that has the ability to be
daisy chained up to 8 units.



When I run conducted emissions, I’m wondering if I need to insist
on having 8 units plugged in at once i.e. fully populated, OR, can
I just test one fixture at a time since that’s how the system is
likely to be used also..



Is there a legal requirement or precedent on how this should be
tested as I’m going round in circles arguing with myself here.



Thanks,



Derek.



SSCLabs,

Reno, NV.

-



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Re: [PSES] Adding more than one EUT

[Douglas Powell]

As I recall, this topic came up once before on this forum.  But try as I
might, I'm unable to find any notes on it.

The idea, as I remember, was you test a single DUT, and then add another,
and another, until emissions do not increase appreciably or become
asymptotic with enough margin to the limit. This idea had "N+1" in the
title.  I have studied multiple noise sources in the context of audio white
noise from cooling fans (up to 14 at a time) and the noise increase is
approximated by the RSS (root-sum-square) function.  However RF EMC can be
very different because often the emissions are very narrow band and
sometimes synchronous, or 100% additive.

I would appreciate anyone pointing me in the right direction on what the
rules actually are.

Best regards, Doug

Douglas E Powell
Laporte, Colorado USA

On Fri, Feb 17, 2023, 7:56 PM Ken Javor  wrote:

> I’m finding this an extremely interesting discussion. I don’t have
> anything definitive to offer, but I do have a question to help stir the pot.
>
> If the possibility that multiple items might be used together and that
> emissions will be additive in some fashion is a justification for testing
> multiple units at a time, what about ... light bulbs?
>
> Meaning CFLs or LEDs.
>
> My house is full of them.  It is reasonable to assume that most
> homes/businesses are. Perhaps the emissions limits for these were based on
> this reasonably foreseeable outcome?
>
> Ken Javor
> Phone: (256) 650-5261
>
>
> --
> *From: *John Mcbain 
> *Reply-To: *John Mcbain 
> *Date: *Fri, 17 Feb 2023 14:22:44 -0800
> *To: *
> *Subject: *Re: [PSES] Adding more than one EUT
>
> Hi Derek -
>
> Typical requirement for a unit that may be sold and used in multiples
> (that is, all the units can be sold together as one product) is you can
> test just one IF adding the other units does not increase the emissions.
>
> Of course the most practical way to determine that is to assemble the
> multiple units to see what happens.  If the test result for testing max.
> connected units compared to testing only one unit shows no significant
> difference, then you're good - but definitely archive those test results!
>
> If you can't pass the test with all units connected, then whatever you do,
> don't let Marketing create a multiple-unit product to sell.  ;-)
>
> Similarly, the desktop PC system that James mentioned would have all power
> cords separately tested for conducted emissions as a fully connected system
> (monitor, printer, scanner, etc. attached) if it is a  product sold as a
> complete all-included system.
>
> Best regards,
> John McBain
>
>
> On Fri, Feb 17, 2023 at 1:59 PM James Pawson (U3C) <
> ja...@unit3compliance.co.uk> wrote:
>
>
> Hi Derek,
>
>
> Is the daisy chain connection the AC supply or some other power bus?
>
>
> How is 8 units daisy chained any different to 8 separate units all on the
> same power bus? We are looking for individual emission contributions from
> each connected unit.
>
>
> If measuring conducted emissions on a desktop pc (y'know, the big ones we
> had before everyone had laptops to work from home...) the you would just
> measure the PC, not the monitor and printer and scanner and modem and and
> and...
>
>
> Just thinking aloud
>
> All the best
>
> James
>
>
>  Lfresearch wrote 
>
> Hi folks,
>
>
>
> I’ve been asked to test a light fixture that has the ability to be daisy
> chained up to 8 units.
>
>
>
> When I run conducted emissions, I’m wondering if I need to insist on
> having 8 units plugged in at once i.e. fully populated, OR, can I just test
> one fixture at a time since that’s how the system is likely to be used
> also..
>
>
>
> Is there a legal requirement or precedent on how this should be tested as
> I’m going round in circles arguing with myself here.
>
>
>
> Thanks,
>
>
>
> Derek.
>
>
>
> SSCLabs,
>
> Reno, NV.
>
> -
>
> 
>
> This message is from the IEEE Product Safety Engineering Society emc-pstc
> discussion list. To post a message to the list, send your e-mail to <
> emc-p...@ieee.org>
>
>
>
> All emc-pstc postings are archived and searchable on the web at:
>
> http://www.ieee-pses.org/emc-pstc.html
>
>
>
> Website:  http://www.ieee-pses.org/
>
> Instructions:  http://www.ieee-pses.org/list.html (including how to
> unsubscribe)
>
> List rules: http://www.ieee-pses.org/listrules.html
>
>
>
> For help, send mail to the list administrators:
>
> Mike Cantwell 
>
>
>
> For policy questions, send mail t

Re: [PSES] Adding more than one EUT

[T.Sato]

On Fri, 17 Feb 2023 21:12:40 -0800,
  John Mcbain  wrote:

> The key is testing the .  If all the light bulbs in your house and
> the connecting wiring was sold as a single product, then presumably it
> would have been tested for EMC in that configuration.  I doubt that is what
> happened.  

Well, standards usually require to test product, in a representative
or minimum configuration.

However, in case of the EMC Directive, it requires "... it complies
with this Directive when properly installed, maintained and used for
its intended purpose."

If if is considered that to install tens of LED lights in a house is
covered by the "intended purpose", shouldn't the LED lights still
comply with the essential requirements of the Directive in that
configuration, too?

Regards,
Tom


> On Fri, Feb 17, 2023 at 6:56 PM Ken Javor 
> wrote:
> 
>> I’m finding this an extremely interesting discussion. I don’t have
>> anything definitive to offer, but I do have a question to help stir the pot.
>>
>> If the possibility that multiple items might be used together and that
>> emissions will be additive in some fashion is a justification for testing
>> multiple units at a time, what about ... light bulbs?
>>
>> Meaning CFLs or LEDs.
>>
>> My house is full of them.  It is reasonable to assume that most
>> homes/businesses are. Perhaps the emissions limits for these were based on
>> this reasonably foreseeable outcome?
>>
>> Ken Javor
>> Phone: (256) 650-5261
>>
>>
>> --------------
>> *From: *John Mcbain 
>> *Reply-To: *John Mcbain 
>> *Date: *Fri, 17 Feb 2023 14:22:44 -0800
>> *To: *
>> *Subject: *Re: [PSES] Adding more than one EUT
>>
>> Hi Derek -
>>
>> Typical requirement for a unit that may be sold and used in multiples
>> (that is, all the units can be sold together as one product) is you can
>> test just one IF adding the other units does not increase the emissions.
>>
>> Of course the most practical way to determine that is to assemble the
>> multiple units to see what happens.  If the test result for testing max.
>> connected units compared to testing only one unit shows no significant
>> difference, then you're good - but definitely archive those test results!
>>
>> If you can't pass the test with all units connected, then whatever you do,
>> don't let Marketing create a multiple-unit product to sell.  ;-)
>>
>> Similarly, the desktop PC system that James mentioned would have all power
>> cords separately tested for conducted emissions as a fully connected system
>> (monitor, printer, scanner, etc. attached) if it is a  product sold as a
>> complete all-included system.
>>
>> Best regards,
>> John McBain
>>
>>
>> On Fri, Feb 17, 2023 at 1:59 PM James Pawson (U3C) <
>> ja...@unit3compliance.co.uk> wrote:
>>
>>
>> Hi Derek,
>>
>>
>> Is the daisy chain connection the AC supply or some other power bus?
>>
>>
>> How is 8 units daisy chained any different to 8 separate units all on the
>> same power bus? We are looking for individual emission contributions from
>> each connected unit.
>>
>>
>> If measuring conducted emissions on a desktop pc (y'know, the big ones we
>> had before everyone had laptops to work from home...) the you would just
>> measure the PC, not the monitor and printer and scanner and modem and and
>> and...
>>
>>
>> Just thinking aloud
>>
>> All the best
>>
>> James
>>
>>
>>  Lfresearch wrote 
>>
>> Hi folks,
>>
>>
>>
>> I’ve been asked to test a light fixture that has the ability to be daisy
>> chained up to 8 units.
>>
>>
>>
>> When I run conducted emissions, I’m wondering if I need to insist on
>> having 8 units plugged in at once i.e. fully populated, OR, can I just test
>> one fixture at a time since that’s how the system is likely to be used
>> also..
>>
>>
>>
>> Is there a legal requirement or precedent on how this should be tested as
>> I’m going round in circles arguing with myself here.
>>
>>
>>
>> Thanks,
>>
>>
>>
>> Derek.
>>
>>
>>
>> SSCLabs,
>>
>> Reno, NV.
>>
>> -
>>
>> 
>>
>> This message is from the IEEE Product Safety Engineering Society emc-pstc
>> discussion list. To post a message to the list, send your e-mail to <
>> emc-p...@ieee.org>
>>
>>
&

Re: [PSES] Adding more than one EUT

[John Mcbain]

Hi Ken -

The key is testing the .  If all the light bulbs in your house and
the connecting wiring was sold as a single product, then presumably it
would have been tested for EMC in that configuration.  I doubt that is what
happened.  

The justification is not that multiple products *could* be connected
together, it is that they are sold together as a single product so they
*will* be connected together - and in a specific configuration.

Best regards,
John McBain


On Fri, Feb 17, 2023 at 6:56 PM Ken Javor 
wrote:

> I’m finding this an extremely interesting discussion. I don’t have
> anything definitive to offer, but I do have a question to help stir the pot.
>
> If the possibility that multiple items might be used together and that
> emissions will be additive in some fashion is a justification for testing
> multiple units at a time, what about ... light bulbs?
>
> Meaning CFLs or LEDs.
>
> My house is full of them.  It is reasonable to assume that most
> homes/businesses are. Perhaps the emissions limits for these were based on
> this reasonably foreseeable outcome?
>
> Ken Javor
> Phone: (256) 650-5261
>
>
> --
> *From: *John Mcbain 
> *Reply-To: *John Mcbain 
> *Date: *Fri, 17 Feb 2023 14:22:44 -0800
> *To: *
> *Subject: *Re: [PSES] Adding more than one EUT
>
> Hi Derek -
>
> Typical requirement for a unit that may be sold and used in multiples
> (that is, all the units can be sold together as one product) is you can
> test just one IF adding the other units does not increase the emissions.
>
> Of course the most practical way to determine that is to assemble the
> multiple units to see what happens.  If the test result for testing max.
> connected units compared to testing only one unit shows no significant
> difference, then you're good - but definitely archive those test results!
>
> If you can't pass the test with all units connected, then whatever you do,
> don't let Marketing create a multiple-unit product to sell.  ;-)
>
> Similarly, the desktop PC system that James mentioned would have all power
> cords separately tested for conducted emissions as a fully connected system
> (monitor, printer, scanner, etc. attached) if it is a  product sold as a
> complete all-included system.
>
> Best regards,
> John McBain
>
>
> On Fri, Feb 17, 2023 at 1:59 PM James Pawson (U3C) <
> ja...@unit3compliance.co.uk> wrote:
>
>
> Hi Derek,
>
>
> Is the daisy chain connection the AC supply or some other power bus?
>
>
> How is 8 units daisy chained any different to 8 separate units all on the
> same power bus? We are looking for individual emission contributions from
> each connected unit.
>
>
> If measuring conducted emissions on a desktop pc (y'know, the big ones we
> had before everyone had laptops to work from home...) the you would just
> measure the PC, not the monitor and printer and scanner and modem and and
> and...
>
>
> Just thinking aloud
>
> All the best
>
> James
>
>
>  Lfresearch wrote 
>
> Hi folks,
>
>
>
> I’ve been asked to test a light fixture that has the ability to be daisy
> chained up to 8 units.
>
>
>
> When I run conducted emissions, I’m wondering if I need to insist on
> having 8 units plugged in at once i.e. fully populated, OR, can I just test
> one fixture at a time since that’s how the system is likely to be used
> also..
>
>
>
> Is there a legal requirement or precedent on how this should be tested as
> I’m going round in circles arguing with myself here.
>
>
>
> Thanks,
>
>
>
> Derek.
>
>
>
> SSCLabs,
>
> Reno, NV.
>
> -
>
> 
>
> This message is from the IEEE Product Safety Engineering Society emc-pstc
> discussion list. To post a message to the list, send your e-mail to <
> emc-p...@ieee.org>
>
>
>
> All emc-pstc postings are archived and searchable on the web at:
>
> http://www.ieee-pses.org/emc-pstc.html
>
>
>
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>
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> -
> 
>
> Thi

Re: [PSES] Adding more than one EUT

[Ken Javor]

I¹m finding this an extremely interesting discussion. I don¹t have anything
definitive to offer, but I do have a question to help stir the pot.

If the possibility that multiple items might be used together and that
emissions will be additive in some fashion is a justification for testing
multiple units at a time, what about ... light bulbs?

Meaning CFLs or LEDs.

My house is full of them.  It is reasonable to assume that most
homes/businesses are. Perhaps the emissions limits for these were based on
this reasonably foreseeable outcome?

Ken Javor
Phone: (256) 650-5261



From: John Mcbain 
Reply-To: John Mcbain 
Date: Fri, 17 Feb 2023 14:22:44 -0800
To: 
Subject: Re: [PSES] Adding more than one EUT

Hi Derek -

Typical requirement for a unit that may be sold and used in multiples (that
is, all the units can be sold together as one product) is you can test just
one IF adding the other units does not increase the emissions.

Of course the most practical way to determine that is to assemble the
multiple units to see what happens.  If the test result for testing max.
connected units compared to testing only one unit shows no significant
difference, then you're good - but definitely archive those test results!

If you can't pass the test with all units connected, then whatever you do,
don't let Marketing create a multiple-unit product to sell.  ;-)

Similarly, the desktop PC system that James mentioned would have all power
cords separately tested for conducted emissions as a fully connected system
(monitor, printer, scanner, etc. attached) if it is a  product sold as a
complete all-included system.

Best regards,
John McBain


On Fri, Feb 17, 2023 at 1:59 PM James Pawson (U3C)
 wrote:
> 
> Hi Derek,
> 
> 
> Is the daisy chain connection the AC supply or some other power bus?
> 
> 
> How is 8 units daisy chained any different to 8 separate units all on the same
> power bus? We are looking for individual emission contributions from each
> connected unit.
> 
> 
> If measuring conducted emissions on a desktop pc (y'know, the big ones we had
> before everyone had laptops to work from home...) the you would just measure
> the PC, not the monitor and printer and scanner and modem and and and...
> 
> 
> Just thinking aloud
> 
> All the best
> 
> James 
> 
> 
>  Lfresearch wrote 
> 
> Hi folks,
> 
> 
> 
> I¹ve been asked to test a light fixture that has the ability to be daisy
> chained up to 8 units.
> 
> 
> 
> When I run conducted emissions, I¹m wondering if I need to insist on having 8
> units plugged in at once i.e. fully populated, OR, can I just test one fixture
> at a time since that¹s how the system is likely to be used also..
> 
> 
> 
> Is there a legal requirement or precedent on how this should be tested as I¹m
> going round in circles arguing with myself here.
> 
> 
> 
> Thanks,
> 
> 
> 
> Derek.
> 
> 
> 
> SSCLabs,
> 
> Reno, NV.
> 
> -
> 
> 
> 
> This message is from the IEEE Product Safety Engineering Society emc-pstc
> discussion list. To post a message to the list, send your e-mail to
> 
> 
> 
> 
> All emc-pstc postings are archived and searchable on the web at:
> 
> http://www.ieee-pses.org/emc-pstc.html
> 
> 
> 
> Website:  http://www.ieee-pses.org/
> 
> Instructions:  http://www.ieee-pses.org/list.html (including how to
> unsubscribe)
> 
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> 
> 
> 
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> -
> 
> 
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Re: [PSES] Adding more than one EUT

[John Mcbain]

Hi Derek -

Typical requirement for a unit that may be sold and used in multiples (that
is, all the units can be sold together as one product) is you can test just
one IF adding the other units does not increase the emissions.

Of course the most practical way to determine that is to assemble the
multiple units to see what happens.  If the test result for testing max.
connected units compared to testing only one unit shows no significant
difference, then you're good - but definitely archive those test results!

If you can't pass the test with all units connected, then whatever you do,
don't let Marketing create a multiple-unit product to sell.  ;-)

Similarly, the desktop PC system that James mentioned would have all power
cords separately tested for conducted emissions as a fully connected system
(monitor, printer, scanner, etc. attached) if it is a  product sold as a
complete all-included system.

Best regards,
John McBain


On Fri, Feb 17, 2023 at 1:59 PM James Pawson (U3C) <
ja...@unit3compliance.co.uk> wrote:

> Hi Derek,
>
> Is the daisy chain connection the AC supply or some other power bus?
>
> How is 8 units daisy chained any different to 8 separate units all on the
> same power bus? We are looking for individual emission contributions from
> each connected unit.
>
> If measuring conducted emissions on a desktop pc (y'know, the big ones we
> had before everyone had laptops to work from home...) the you would just
> measure the PC, not the monitor and printer and scanner and modem and and
> and...
>
> Just thinking aloud
>
> All the best
>
> James
>
>
>  Lfresearch wrote 
>
> Hi folks,
>
>
>
> I’ve been asked to test a light fixture that has the ability to be daisy
> chained up to 8 units.
>
>
>
> When I run conducted emissions, I’m wondering if I need to insist on
> having 8 units plugged in at once i.e. fully populated, OR, can I just test
> one fixture at a time since that’s how the system is likely to be used
> also..
>
>
>
> Is there a legal requirement or precedent on how this should be tested as
> I’m going round in circles arguing with myself here.
>
>
>
> Thanks,
>
>
>
> Derek.
>
>
>
> SSCLabs,
>
> Reno, NV.
>
> -
>
> 
>
> This message is from the IEEE Product Safety Engineering Society emc-pstc
> discussion list. To post a message to the list, send your e-mail to <
> emc-p...@ieee.org>
>
>
>
> All emc-pstc postings are archived and searchable on the web at:
>
> http://www.ieee-pses.org/emc-pstc.html
>
>
>
> Website: http://www.ieee-pses.org/
>
> Instructions: http://www.ieee-pses.org/list.html (including how to
> unsubscribe)
>
> List rules: http://www.ieee-pses.org/listrules.html
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>
>
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>
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>
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> -
> 
>
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> discussion list. To post a message to the list, send your e-mail to 
> emc-p...@ieee.org
>
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Re: [PSES] Adding more than one EUT

[James Pawson (U3C)]

Hi Derek,

Is the daisy chain connection the AC supply or some other power bus?

How is 8 units daisy chained any different to 8 separate units all on the same 
power bus? We are looking for individual emission contributions from each 
connected unit.

If measuring conducted emissions on a desktop pc (y'know, the big ones we had 
before everyone had laptops to work from home...) the you would just measure 
the PC, not the monitor and printer and scanner and modem and and and...

Just thinking aloud
All the best
James 

 Lfresearch wrote 

>Hi folks,
>
>I’ve been asked to test a light fixture that has the ability to be daisy 
>chained up to 8 units.
>
>When I run conducted emissions, I’m wondering if I need to insist on having 8 
>units plugged in at once i.e. fully populated, OR, can I just test one fixture 
>at a time since that’s how the system is likely to be used also..
>
>Is there a legal requirement or precedent on how this should be tested as I’m 
>going round in circles arguing with myself here.
>
>Thanks,
>
>Derek.
>
>SSCLabs,
>Reno, NV.
>-
>
>This message is from the IEEE Product Safety Engineering Society emc-pstc 
>discussion list. To post a message to the list, send your e-mail to 
>
>
>All emc-pstc postings are archived and searchable on the web at:
>http://www.ieee-pses.org/emc-pstc.html
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>unsubscribe)
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>
>For help, send mail to the list administrators:
>Mike Cantwell 
>
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Re: [PSES] Adding more than one EUT

[MIKE SHERMAN]

 
 
  
   My recollection from the EMC directive is that one is supposed to test the product in a manufacturer’s intended configuration that creates the most emissions. 
  
  
   
On 02/17/2023 2:20 PM Lfresearch <00734758d943-dmarc-requ...@listserv.ieee.org> wrote:
   
   

   
   

   
   
Hi folks,
   
   

   
   
I’ve been asked to test a light fixture that has the ability to be daisy chained up to 8 units.
   
   

   
   
When I run conducted emissions, I’m wondering if I need to insist on having 8 units plugged in at once i.e. fully populated, OR, can I just test one fixture at a time since that’s how the system is likely to be used also..
   
   

   
   
Is there a legal requirement or precedent on how this should be tested as I’m going round in circles arguing with myself here.
   
   

   
   
Thanks,
   
   

   
   
Derek.
   
   

   
   
SSCLabs,
   
   
Reno, NV.
   
   
-
   
   

   
   
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