My understanding:
Receptacles are not de-rated.
A single load cannot exceed 80% (or some such percentage) of the branch circuit
loading to allow other loads on the same branch circuit. If a single
receptacle on the branch circuit, then the (single) load can be 100% of the
branch circuit
That isn't a 'condition'. The conditions are the items in the a-b-c list
in 6.1.
John Woodgate OOO-Own Opinions Only
J M Woodgate and Associates www.woodjohn.uk
Rayleigh, Essex UK
On 2017-10-11 21:42, James Pawson (U3C) wrote:
It was the symmetrical control for the powering of heating elements
Hello Experts,
I forward this as a potential opportunity for someone in our community.
US test firm seeking experienced Machinery Directive engineers to support
diverse clientele in the US.
Engagement requires travel to client locations in the US to assess compliance
with Machinery
It was the symmetrical control for the powering of heating elements part that
was the previous condition that was fulfilled.
Hope this helps
James
John Woodgate wrote
>OK, I've sent a digest to the committee chair. Meanwhile, I noticed
>something that I don't quite understand:
>
OK, I've sent a digest to the committee chair. Meanwhile, I noticed
something that I don't quite understand:
You say that "Clause 6.1 also says that symmetrical control for
professional equipment is OK provided one of the “above conditions” is
fulfilled (which it is, see previous bullet)"
Not sure if your question is specific to NEC or not. There are other
standards, for example UL 508A that have similar rules that are not specific to
circuit sizes.
And the rules are not all straight forward as they apply to conductor sizing,
branch circuit protection, connectors/components,
NEC article 210 writes about “branch circuits” up to 600V. I didn’t see a
limit on current, so we’ve always applied it to OCP and ampacity for all
conductors on circuits where the current is expected to be “continuous”, as
defined in the code. ( we go up to 2000A on a 575V circuit on a custom
One last quick question, if I may, while we are all up on the NEC.
Just to confirm, the 80% rule only applies to 15A, 20A, and 30A branch
circuits. 40A and 50A branch circuits do not have the 80% rule, even in a
multiple-outlet configuration? I know these larger circuits are generally
Yes, of course quite a thin conductor will carry enough current to
operate the protection, because it doesn't have time to get seriously hot.
John Woodgate OOO-Own Opinions Only
J M Woodgate and Associates www.woodjohn.uk
Rayleigh, Essex UK
On 2017-10-11 19:35, Kunde, Brian wrote:
I know I
I don't know for sure. I was told that the low-frequency emission
standards apply whether they are cited in a Generic or not. 61000-6-3
isn't restricted to 'residential, it includes 'commercial and light
industrial, which is why 61000-3-11 and -12 are cited. Maybe 61000-6-3
assumes a
Since you're asking for an opinion and since IEC would allow it, I think it's
reasonable to allow it in N.Am too. There is no apparent hazard; the 15A OCPD
adequately protects both the connector and the cordage.
Ralph McDiarmid
Product Compliance
Engineering
Solar Business
Schneider Electric
I know I started this thread, so I'm going to circuit back via another
direction.
The NEC allows a product with an 18 awg power cord (rated 10 amps), a 15 amp
plug, and C13 IEC connector (15 amp) to be plugged into a 15 amp branch
circuit. OH, you can also plug it into a 20 amp branch circuit
That is an interesting technical point. Notice that EN61000-6-3 (generic
residential) calls out 61000-3-2, -3, -11 and -12, but EN61000-6-4
(industrial) does not.
Presumably, EN61000-6-4 makes full provision for the apparatus ?
Ralph McDiarmid
Product Compliance
Engineering
Solar Business
For sure the A/C unit was not the original and it's possible the original had a
NEMA 5-20P plug. It's only cooling the small bedroom and bath. The unit is
rated 8.6A and the nameplate (picture of which is in my files) says in big bold
letters USE ON SINGLE OUTLET CIRCUIT ONLY.
-Dave
All,
So the NEC allows you to draw the full 15 amps from a 15 amp receptacle IF it
is on a dedicated circuit. BUT if the circuit is wired to more than one
receptacle, then the product cannot draw more than 12 amps. What difference
does that make? Same product, same power cord, same plug and
Had a condo with a smallish through-the-wall A/C unit with NEMA 5-15P plug.
In the room on one side of the unit was a dedicated 20A single outlet for the
A/C unit. In the room on the other side easily within reach of the cord was a
standard duplex outlet on the room circuit. Guess which
Dave,
The question is what was the rated current on the A/C unit? With the
15A plug it was probably rated at 12A unless it clearly specified a 'dedicated
circuit'. I guess it's too long ago to go check on it.
:>) br, Pete
Peter E Perkins, PE
Principal Product Safety &
Ralph, Ted et al,
Dunno how many times I have had this conversation with the project
engineer who wants to use the full rated current from the duplex outlet (and
not leave any for the other user who plugs into that outlet - which gives rise
to the 80% rule) - except if they want to
61000-3-2, -3, -11 and -12 do not have to be cited in the Generics;
they apply independently. 61000-3-4 assumes a dedicated MV/LV
transformer, but the product is only 3 kW, so one can't assume that.
John Woodgate OOO-Own Opinions Only
J M Woodgate and Associates www.woodjohn.uk
Rayleigh,
I wonder if your customer's triac equipment falls under the EN61000-6-4 (EMC)
Emission standard for
industrial environments? I didn't see 61000-3-2 called out in that generic
standard.
Ralph McDiarmid
Product Compliance
Engineering
Solar Business
Schneider Electric
From: James Pawson (U3C)
If there is only a very remote chance of the product being connected to
*public* LV mains supplies (as opposed to industrial supplies from a
dedicated MV/LV transformer), 61000-3-2 doesn't apply. Does it meet the
Class A limits? I agree that it's 'professional equipment', but, as you
see, the
Hello John,
It uses phase angle control hence the concern about the harmonics generated.
Manufacturer specs are single phase, 230V nominal, 3kW.
Typically used at less than a 15% duty cycle, often less, in an industrial
environment or powered from a generator.
My *feeling* is that should
Sounds like an example of the 125% rule for continuous (>3hr) current. (20/16)
Ralph McDiarmid
Product Compliance
Engineering
Solar Business
Schneider Electric
From: Ted Eckert [mailto:07cf6ebeab9d-dmarc-requ...@ieee.org]
Sent: Wednesday, October 11, 2017 5:50 AM
To:
I should also have asked what the rated power actually is, and whether
it's 1-phase or 3-phase?
John Woodgate OOO-Own Opinions Only
J M Woodgate and Associates www.woodjohn.uk
Rayleigh, Essex UK
On 2017-10-11 16:54, John Woodgate wrote:
True, but it's a cumbersome procedure and is not
True, but it's a cumbersome procedure and is not clearly enough
indicated. I will try to get an improvement.
John Woodgate OOO-Own Opinions Only
J M Woodgate and Associates www.woodjohn.uk
Rayleigh, Essex UK
On 2017-10-11 15:59, Scott Aldous wrote:
Hi James,
The flowchart in Clause 7 in the
I agree that there appears to be a need for clarification, and I will
take that up with the committee responsible. But for your particular
case, what is critical is the nature of the 'triac control'. Is it
phase-angle control, or 'burst firing' or something else?
John Woodgate OOO-Own
Hi Scott, thanks for your input.
I agree with you, but as far as I can tell the equipment does comply with the
techniques allowed in 6.1.
Then it gets passed down the chart to the “Belongs to exceptions of Clause 7…”
box where it is exempted and deemed to conform without ever having
Hi James,
The flowchart in Clause 7 in the version of the standard that I have access
to sends you to Clause 4 for professional equipment that uses techniques
not allowed by 6.1. The second paragraph of Clause 4 addresses professional
equipment that does not comply with the requirements of the
Hi folks,
I apologise as I seem to be all take and not much give on this forum at the
moment; I'm trying to do a lot of learning very quickly. Someone ask a
question about HDMI so that I can feel useful!
Today's question is what appears to be a contradiction in IEC
61000-3-2:2014.
*
NFPA 70 allows 20 A connectors to be used at 20 A under a number of
circumstances. The derating issue only applies in certain cases. Just changing
the rating doesn’t resolve the issue as it would eliminate already accepted
safe use of the connectors at their full rating.
Ted Eckert
Microsoft
Yes, it could be difficult to change to respecting the rated values, so
how about respecting the de-rated values instead? Instead of saying that
you can only use this 20 A connector up to 16 A, call it a 16 A connector?
John Woodgate OOO-Own Opinions Only
J M Woodgate and Associates
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