Re: [PSES] Moter Overload Protection with Supplemental Protector

[Ted Eckert]

Mr. O’Connell gives me too much credit. It’s been 10 years since I did much 
work in this 
area. My copy 
of NFPA 79 started to grow moldy and I had to remove it from under my pillow.



I’m not sure I have much to add to the discussion. I believe the guidance given 
by Mr. Nyffenegger is correct and Mr. O’Connell has given accurate additional 
information.


Ted Eckert
Microsoft Corporation

The opinions expressed are my own and do not necessarily reflect those of my 
employer, the NFPA, ASHRAE, IEC TC108 or the International Brotherhood of Motor 
Thermal Protection Design and Installation Engineers (IBMTPDIE).

-Original Message-
From: Brian O'Connell [mailto:oconne...@tamuracorp.com]
Sent: Friday, March 10, 2017 11:35 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Moter Overload Protection with Supplemental Protector



Ted Eckert could probably answer this more completely, as has been rumored that 
he sleeps with a copy of NFPA79 beneath pillow, and has his phone configured 
where 911 auto-dials members of TC108.



Motor protection - inverse time breaker sized to 250% of FLC, see table 430.52; 
but for 1/2 hp, NEC wants 14 awg in the raceway.



FLC should be per tables 430.247, 430.248, 430.250, 430.6(A)(1).

FLA is per the motor's nameplate rating; and is used to determine conductor 
requirements per 430.22 and branch ckt overcurrent sizing per 430.52 and 430.62.



If motor indicates FLC on nameplate, ignore the HP rating and use FLC number.



As both of your scenarios are powered from OC-protected branch ckt, 
'supplemental' current interrupt devices would be ok per code, but would not 
recommend for some motors. If you are wired into a 'derived' ckt, you would 
also need to assess the limits of the materials. Branch ckt protection devices 
are for short ckt only - they should not be intended to protect for motor 
overloads. Probably preaching to choir, but article 240 is *not* scoped for 
motors, and many do not want to use article 430 to avoid the bigger FLA and FLC 
current protection requirements.



Brian



-Original Message-

From: Kunde, Brian [mailto:brian_ku...@lecotc.com]

Sent: Friday, March 10, 2017 10:49 AM

To: EMC-PSTC@LISTSERV.IEEE.ORG

Subject: [PSES] Moter Overload Protection with Supplemental Protector



Greetings experts.



This question applies to both North America rules (NEC) keeping in mind the 
rest of the world including Europe BUT my example will be for a 115Vac 60hz 
device.



My example product is used in the Workplace but not typically in an industrial 
environment (if that matters). It's not a home appliance or power tool.



Consider an End Product powered by 115Vac 60hz from a standard 16AWG power cord 
with a NEMA-5-15 plug, from a 15 amp receptacle (15 amp Branch Circuit).  
Within this product is a 1/2 hp motor with an Full-Load Amp (FLA) rating of 5 
amp. The motor can run continuous in this application. The motor does not have 
integrated over temperature protection.



Scenario 1: If this was a single phase AC motor, we would have to provide 
Overload Protection. According to the NEC, a fuse or circuit breaker no larger 
than 6.25 amp (FLA x 125%) can be used (lets ignore start up current for now).  
Can this Overload Protector be a "Supplemental Protector" (UL 1077 circuit 
breaker) or does it have to be a UL 489 circuit breaker or some other type of 
device?



Scenario 2: If an Inverter, Frequency Drive, PWM Motor Controller, etc. is used 
to drive an AC or PWM DC motor (1/2hp), the Branch Circuit is not stressed by 
Motor Start currents since the motor is soft started. So for example, if we 
have a 1/2hp 90Vdc motor that is driven by a PWM controller, can the Overload 
Protector be a Supplemental Protector?  If not, what does it have to be and why?



Scenario 3: If the inverter, frequency drive, PWN motor controller, etc. 
provides Overload Protection for the motor, do we even need to add an 
additional Overload protector?  Can we use a single Supplemental protector for 
the entire product and not worry about the motor? In this scenario, I assume 
the motor controller would have to be Listed by a safety agency and 
specifically call out the overload protection feature in the datasheet.





What other concerns might I need to know about? I'm trying to make sense of the 
NEC article 430 but it doesn't seem to address motors driven by Motor 
Controllers. Can I assume that when a motor is driven by a Motor Controller 
(inverter, freq. drive, PWM, etc.) that the NEC 430 does not apply because the 
motor is not being directly powered by a Branch Circuit?



Thanks to all in advance.

The Other Brian













LECO Corporation Notice: This communication may contain confidential 
information intended for the named recipient(s) only. If you received this by 
mistake, please destroy it and notify us of 

Re: [PSES] EMC co-location distance question

[Regan Arndt]

Thanks to everyone who chimed in. Much appreciated!

From: dward [mailto:dw...@pctestlab.com]
Sent: Thursday, March 09, 2017 12:01 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] EMC co-location distance question

Here is the problem with the ‘2 dB rule’.  If there are only two ports it 
simply makes more sense to cable the ports.  If the device passes, go no 
further.  If you only fill one port, then you have to still fill the remaining 
port to meet the 2dB rule, even if it passes.  So, why waste the time?
The 2dB rule is basically meant for those systems having many identical ports.

The same reasoning can be applied to adding identical modules.  If a host only 
has the capacity of two identical modules, you will need to put both modules in 
and test once.  If you use the 2dB rule for identical modules, you test one 
host with one module, then you must still add the second identical module to 
meet the 2dB rule.  Again, why waste the time – test both, get done.

The 2dB rule in both scenarios is still for those instances where many of the 
same identical modules or ports are used in a single host’; but then it appears 
no one defines what “many” means.  In that case, put one module in, then put 
the second.  If no more than 2dB is seen, test done; if more than 2dB put the 
third in.  If still more than 2dB keep going till all modules are in place or 
no more than 2dB increase seen.

​Thanks
Dennis Ward
This communication and its attachements contain information from PCTEST 
Engineering Laboratory, Inc., and is intended for the exclusive use of the 
recipient(s) named above.  It may contain information that is confidential 
and/or legally privileged.  Any unauthorized use that may compromise that 
confidentiality via distribution or disclosure is prohibited.  Please notify 
the sender immediately if you receive this communication in error, and delete 
it from your computer system.  Usage of PCTEST email addresses for non-business 
related activities is strictly prohibited.  No warranty is made that the e-mail 
or attachments(s) are free from computer virus or other defect.  Thank you.

From: Bill Stumpf [mailto:bstu...@dlsemc.com]
Sent: Thursday, March 9, 2017 11:26 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] EMC co-location distance question

Right - ANSI C63.4 still makes reference to the "2dB rule"

Bill

From: Adam Dixon [mailto:lanterna.viri...@gmail.com]
Sent: Thursday, March 09, 2017 1:03 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] EMC co-location distance question

It's been awhile, but at the time when wanting to understand modular test 
requirements, the 2dB asymptote/leveling off  was a reference in FCC Part 15 
Section 15.31 (a) (3)  pointing to ANSI C63.4-2003.
Regards,
Adam in Atlanta

On Thu, Mar 9, 2017 at 1:16 PM, Sundstrom, Mike 
> wrote:
Regan,
In regards to the daisy chaining:
Hook up equipment (daisy chaining) until such a time as you don’t get a 2 dB 
increase of any unwanted signals. I think this is in ANSI or CISPR?
Everyone,
What am I remembering partly here?


Thanks,

Michael Sundstrom
Garmin Compliance Engineer
2-2606
(913) 440-1540
KB5UKT

"We call it theory when we know much about something but nothing works,
and practice when everything works but nobody knows why."  -- Albert 
Einstein

From: Regan Arndt [mailto:re...@empowermicro.com]
Sent: Thursday, March 09, 2017 11:50 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] EMC co-location distance question

Hi Bill. Thanks for this great info! Much appreciated.

The second part of my original email was merely philosophical discussion 
points. Let me clarify. I would love to hear what people think:


1. How many different types of ancillary equipment shall you test with your 
main EUT? i.e. PCs or laptops with HDMI & USB ports……the sky’s the limit as to 
the myriad of devices that now can be connected. Where does one ‘stop’?

a. Also, not all devices (that claim to be Class B) are noise free. I’ve 
personally experienced extremely noisy devices using a reputable brand name 
(yes, FCC logo on the device), but had to exchange it for their competitor to 
ensure no unintentional emissions, so my main EUT passes. (Moral of the 
story….don’t believe everything you read on the label – lol)


2. Another related question: what about identical devices that can be daisy 
chained? i.e. some devices allow a daisy chain of up to 12 or more. (i.e. 
telecom trunk card). Does one use the chamber table as the determination for 
the quantity of daisy chained samples to test? Or does one compile all the max 
# of daisy chained devices on the table despite the congestion of I/O & power 
cables (not recommended)? Or is there a rule of thumb that one shall prove that 
there will not be 

Re: [PSES] Moter Overload Protection with Supplemental Protector

[Brian O'Connell]

Ted Eckert could probably answer this more completely, as has been rumored that 
he sleeps with a copy of NFPA79 beneath pillow, and has his phone configured 
where 911 auto-dials members of TC108.

Motor protection - inverse time breaker sized to 250% of FLC, see table 430.52; 
but for 1/2 hp, NEC wants 14 awg in the raceway.

FLC should be per tables 430.247, 430.248, 430.250, 430.6(A)(1).
FLA is per the motor's nameplate rating; and is used to determine conductor 
requirements per 430.22 and branch ckt overcurrent sizing per 430.52 and 430.62.

If motor indicates FLC on nameplate, ignore the HP rating and use FLC number.

As both of your scenarios are powered from OC-protected branch ckt, 
'supplemental' current interrupt devices would be ok per code, but would not 
recommend for some motors. If you are wired into a 'derived' ckt, you would 
also need to assess the limits of the materials. Branch ckt protection devices 
are for short ckt only - they should not be intended to protect for motor 
overloads. Probably preaching to choir, but article 240 is *not* scoped for 
motors, and many do not want to use article 430 to avoid the bigger FLA and FLC 
current protection requirements.

Brian

-Original Message-
From: Kunde, Brian [mailto:brian_ku...@lecotc.com] 
Sent: Friday, March 10, 2017 10:49 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Moter Overload Protection with Supplemental Protector

Greetings experts.

This question applies to both North America rules (NEC) keeping in mind the 
rest of the world including Europe BUT my example will be for a 115Vac 60hz 
device.

My example product is used in the Workplace but not typically in an industrial 
environment (if that matters). It's not a home appliance or power tool.

Consider an End Product powered by 115Vac 60hz from a standard 16AWG power cord 
with a NEMA-5-15 plug, from a 15 amp receptacle (15 amp Branch Circuit).  
Within this product is a 1/2 hp motor with an Full-Load Amp (FLA) rating of 5 
amp. The motor can run continuous in this application. The motor does not have 
integrated over temperature protection.

Scenario 1: If this was a single phase AC motor, we would have to provide 
Overload Protection. According to the NEC, a fuse or circuit breaker no larger 
than 6.25 amp (FLA x 125%) can be used (lets ignore start up current for now).  
Can this Overload Protector be a "Supplemental Protector" (UL 1077 circuit 
breaker) or does it have to be a UL 489 circuit breaker or some other type of 
device?

Scenario 2: If an Inverter, Frequency Drive, PWM Motor Controller, etc. is used 
to drive an AC or PWM DC motor (1/2hp), the Branch Circuit is not stressed by 
Motor Start currents since the motor is soft started. So for example, if we 
have a 1/2hp 90Vdc motor that is driven by a PWM controller, can the Overload 
Protector be a Supplemental Protector?  If not, what does it have to be and why?

Scenario 3: If the inverter, frequency drive, PWN motor controller, etc. 
provides Overload Protection for the motor, do we even need to add an 
additional Overload protector?  Can we use a single Supplemental protector for 
the entire product and not worry about the motor? In this scenario, I assume 
the motor controller would have to be Listed by a safety agency and 
specifically call out the overload protection feature in the datasheet.


What other concerns might I need to know about? I'm trying to make sense of the 
NEC article 430 but it doesn't seem to address motors driven by Motor 
Controllers. Can I assume that when a motor is driven by a Motor Controller 
(inverter, freq. drive, PWM, etc.) that the NEC 430 does not apply because the 
motor is not being directly powered by a Branch Circuit?

Thanks to all in advance.
The Other Brian






LECO Corporation Notice: This communication may contain confidential 
information intended for the named recipient(s) only. If you received this by 
mistake, please destroy it and notify us of the error. Thank you.

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Re: [PSES] Motor Overload Protection with Supplemental Protector

[Nyffenegger, Dave]

1.  I believe NEC requires all 120V 15A branch circuits with 5015 receptacles 
to be branch circuit protected so the UL 1077 breaker should be fine.  Outside 
of NEC may be another matter.
2/3.  If Inverter, Frequency Drive, PWM Motor Controller provides overload 
protection (they usually do)  then the supplemental   protector should be fine 
as long as it's preceded by branch circuit protection.  But I don't think the 
supplemental protector can provide any motor overload protection by itself.

Your product should probably be design/tested/listed to its own applicable 
standard.  NFPA 70 430 would be for motors installed into a building as part of 
a general construction project.  It would not apply to a separately 
tested/listed portable product plugged into the wall.

-Dave

-Original Message-
From: Kunde, Brian [mailto:brian_ku...@lecotc.com] 
Sent: Friday, March 10, 2017 1:49 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Moter Overload Protection with Supplemental Protector

Greetings experts.

This question applies to both North America rules (NEC) keeping in mind the 
rest of the world including Europe BUT my example will be for a 115Vac 60hz 
device.

My example product is used in the Workplace but not typically in an industrial 
environment (if that matters). It's not a home appliance or power tool.

Consider an End Product powered by 115Vac 60hz from a standard 16AWG power cord 
with a NEMA-5-15 plug, from a 15 amp receptacle (15 amp Branch Circuit).  
Within this product is a 1/2 hp motor with an Full-Load Amp (FLA) rating of 5 
amp. The motor can run continuous in this application. The motor does not have 
integrated over temperature protection.

Scenario 1: If this was a single phase AC motor, we would have to provide 
Overload Protection. According to the NEC, a fuse or circuit breaker no larger 
than 6.25 amp (FLA x 125%) can be used (lets ignore start up current for now).  
Can this Overload Protector be a "Supplemental Protector" (UL 1077 circuit 
breaker) or does it have to be a UL 489 circuit breaker or some other type of 
device?

Scenario 2: If an Inverter, Frequency Drive, PWM Motor Controller, etc. is used 
to drive an AC or PWM DC motor (1/2hp), the Branch Circuit is not stressed by 
Motor Start currents since the motor is soft started. So for example, if we 
have a 1/2hp 90Vdc motor that is driven by a PWM controller, can the Overload 
Protector be a Supplemental Protector?  If not, what does it have to be and why?

Scenario 3: If the inverter, frequency drive, PWN motor controller, etc. 
provides Overload Protection for the motor, do we even need to add an 
additional Overload protector?  Can we use a single Supplemental protector for 
the entire product and not worry about the motor? In this scenario, I assume 
the motor controller would have to be Listed by a safety agency and 
specifically call out the overload protection feature in the datasheet.


What other concerns might I need to know about? I'm trying to make sense of the 
NEC article 430 but it doesn't seem to address motors driven by Motor 
Controllers. Can I assume that when a motor is driven by a Motor Controller 
(inverter, freq. drive, PWM, etc.) that the NEC 430 does not apply because the 
motor is not being directly powered by a Branch Circuit?

Thanks to all in advance.
The Other Brian






LECO Corporation Notice: This communication may contain confidential 
information intended for the named recipient(s) only. If you received this by 
mistake, please destroy it and notify us of the error. Thank you.

-

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discussion list. To post a message to the list, send your e-mail to 


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formats), large files, etc.

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Jim Bacher:  
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All emc-pstc postings are archived and searchable on the web at:
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[PSES] Moter Overload Protection with Supplemental Protector

[Kunde, Brian]

Greetings experts.

This question applies to both North America rules (NEC) keeping in mind the 
rest of the world including Europe BUT my example will be for a 115Vac 60hz 
device.

My example product is used in the Workplace but not typically in an industrial 
environment (if that matters). It's not a home appliance or power tool.

Consider an End Product powered by 115Vac 60hz from a standard 16AWG power cord 
with a NEMA-5-15 plug, from a 15 amp receptacle (15 amp Branch Circuit).  
Within this product is a 1/2 hp motor with an Full-Load Amp (FLA) rating of 5 
amp. The motor can run continuous in this application. The motor does not have 
integrated over temperature protection.

Scenario 1: If this was a single phase AC motor, we would have to provide 
Overload Protection. According to the NEC, a fuse or circuit breaker no larger 
than 6.25 amp (FLA x 125%) can be used (lets ignore start up current for now).  
Can this Overload Protector be a "Supplemental Protector" (UL 1077 circuit 
breaker) or does it have to be a UL 489 circuit breaker or some other type of 
device?

Scenario 2: If an Inverter, Frequency Drive, PWM Motor Controller, etc. is used 
to drive an AC or PWM DC motor (1/2hp), the Branch Circuit is not stressed by 
Motor Start currents since the motor is soft started. So for example, if we 
have a 1/2hp 90Vdc motor that is driven by a PWM controller, can the Overload 
Protector be a Supplemental Protector?  If not, what does it have to be and why?

Scenario 3: If the inverter, frequency drive, PWN motor controller, etc. 
provides Overload Protection for the motor, do we even need to add an 
additional Overload protector?  Can we use a single Supplemental protector for 
the entire product and not worry about the motor? In this scenario, I assume 
the motor controller would have to be Listed by a safety agency and 
specifically call out the overload protection feature in the datasheet.


What other concerns might I need to know about? I'm trying to make sense of the 
NEC article 430 but it doesn't seem to address motors driven by Motor 
Controllers. Can I assume that when a motor is driven by a Motor Controller 
(inverter, freq. drive, PWM, etc.) that the NEC 430 does not apply because the 
motor is not being directly powered by a Branch Circuit?

Thanks to all in advance.
The Other Brian






LECO Corporation Notice: This communication may contain confidential 
information intended for the named recipient(s) only. If you received this by 
mistake, please destroy it and notify us of the error. Thank you.

-

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discussion list. To post a message to the list, send your e-mail to 


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Re: [PSES] Federal Regulations, Title 47

[dward]

If the BT module is a certified BT module not needing SAR, then, while the host 
may not need to pass part 15C requirements, it will still need to pass any 
digital device requirements in part 15B for unintentional radiators.
If the module is not certified, but the transmitter is being certified in the 
host device, this then means the host and BT are subject to two sections of 
part 15.  That being, the transmitter is subject to 15C requirements, and the 
digital part of the device is subject to 15B class B requirements if it is a 
device that could be used in the home.  IF it is strictly an office or 
professional environment, then the BT transmitter would need to meet 15C 
requirements, but the digital device would meet the limit requirements of 15B 
class A requirements.
Thanks 

​
Dennis Ward
This communication and its attachements contain information from PCTEST 
Engineering Laboratory, Inc., and is intended for the exclusive use of the 
recipient(s) named above.  It may contain information that is confidential 
and/or legally privileged.  Any unauthorized use that may compromise that 
confidentiality via distribution or disclosure is prohibited.  Please notify 
the sender immediately if you receive this communication in error, and delete 
it from your computer system.  Usage of PCTEST email addresses for non-business 
related activities is strictly prohibited.  No warranty is made that the e-mail 
or attachments(s) are free from computer virus or other defect.  Thank you.

-Original Message-
From: Ralph McDiarmid [mailto:ralph.mcdiar...@schneider-electric.com] 
Sent: Thursday, March 9, 2017 1:40 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Federal Regulations, Title 47

Dear experts,

If a Bluetooth module is designed into an piece of equipment, does that 
equipment then need to meet technical requirements of CFR Title 47, Part 15, 
Subpart C ?

Ralph McDiarmid
Product Compliance
Engineering
Solar Business
Schneider Electric

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