30A Recept on 20A Circuit - 210.24

[don_resqcapt19]

The code doesn't say anything one way or the other if the receptacle rating for a single receptacle, installed an individual branch circuit, can be higher than the branch circuit rating. Because it doesn't say it the consensus of the majority that have posted on this thread say that makes it ok. Maybe the authors of the Code didn't think it was necessary to put it in black and white that it is not acceptable. Jmho, it's just common sense not to have the receptacle ampere rating higher than the branch circuit rating. It's not idiot proof. (Though in Table 210.21(B)(3) there is an exception to use a 40 or 50 amp receptacle on a 40 amp circuit. Just guessing it was tested by the manufacture and or UL, just a guess.)

Telling me that the single receptacle must have a rating at least equal to that of the branch circuit is very specifically telling me that I can install a receptacle with a rating that is greater than that of the branch circuit. A very common application of this is for industrial pin and sleeve receptacles. The very often exceed the rating of the branch circuit. In many cases there is not a receptacle that can be purchased that matches the rating of the branch circuit and to use one with a rating less than the branch circuit is a violation. One brand that I use has receptacles available in the following sizes, 20, 30, 60 and 150. We have to use the 150 amp rated ones for the 70 amp welder.

Are there any sections in the code that would make it non compliant to install a higher ampere rated single receptacle than the individual branch circuit ampere rating? In other words, by installing the higher ampere rated receptacle are you inadvertently violating another section of the code?
A customer buys a new server to replace an old one. He discovers the plug on the new server will not plug into the existing individual branch circuit wall receptacle outlet. According to the majority that have posted on this thread all that needs to be done is to change out the receptacle to match that of the plug on the new server power cord. Code Compliant? Majority says, Code doesn't say he can't.

No one has said that you can do that. While there is no violation installing the larger rated single receptacle, there is a violation is connecting a load that exceeds that of the branch circuit.

What determines the plug ampere rating that a manufacturer uses for a piece of equipment? Is there an electrical safety standards that dictates the NEMA plug the manufacturer must use for his piece of equipment? Can he use a NEMA 5-15P if his equipment FLA is 14 or 15 amps? Or does NEMA electrical safety standards dictate he must use a NEMA 5-20P? Why? It has to be idiot proof. A 5-20P plug will not physically fit, plug, into a 5-15R receptacle. IF the branch circuit is 20 amps the user can simply change the 15 amp receptacle to a 20 amp receptacle.

1875 watt hair dryers have 15 amp plugs.

According to the majority that have posted on this thread if the branch circuit is an individual 15 amp branch the user can install a single 5-20R receptacle. Code does not specifically say he can't. Therefore it is code compliant. Is it? Doesn't that defeat the purpose the NEMA electrical safety standards configurations for plugs and receptacles ampere ratings? Are there any sections in the Code that may be in violation when the 5-20R is installed on the 15 amp branch circuit?

There are no cases where the installation of the receptacle is a code violation. There may be case where using the receptacle at its rated load would be a code violation.

What if the FLA on the piece of equipment is 16 amps. Many that posted on this thread said no problem. Eventually the breaker will trip open. Guaranteed? Good chance it will never trip.

Yes there is a very good chance it will never trip at 16 or even 18 or 20 amps....so are you saying a single 15 amp receptacle on a 15 amp OCPD is not safe?

Any Code violations come to mind? Here's an easy one 210.22 Permissible Loads, Individual Branch Circuits. So if a single 20 amp receptacle is installed on the individual 15 amp branch circuit is the installation Code compliant? Yeah, according to many that have posted on this thread, but did you violate another section of the code when you installed it?

If the intended use, at the time of installation, has a load less than the rating of the branch circuit, there is no violation.

Best regards,
Jim
[/QUOTE]

 

[don_resqcapt19]

From the panel action on a rejected proposed (PI-2821)change to for the 2020 NEC that would have required single receptacles to comply with the values in Table 210.21(B)(3).
Proposed text: (new is underlined)

(1) Single Receptacle on an Individual Branch Circuit. A single receptacle installed on an individual branch circuit shall have an ampere rating not less than that of the branch circuit and not more than the values in Table 210.21(B)(3).

From submitter substantiation:

Section 210.21(B)(1) contradicts Table 210.21(B)(3) because it does not limit the receptacle size. (B)(1) alone, as written, allows a 30 amp single receptacle on a 20 amp circuit. I don’t believe that was the intent so I added the words to direct the reader to Table 210.21(B)(3) which would limit the receptacle size.

From panel statement:

Section 210.21(B)(1) clearly states that a single receptacle on an individual branch circuit shall have a rating of not less than that of the branch circuit. The present text is clear in this regard. Although an overload condition may occur and be cleared by the overcurrent protective device, a safety hazard is not present should a 30A receptacle be placed on a 20A circuit. Table 210.21(B)((3), as noted in 210.21(B)(3), is addressing two or more receptacles on a branch circuit and therefore is not in conflict with 210.21(B)(1) regarding single receptacles on an individual branch circuit. Manufacturer’s requirements would also apply per 110.3(B)

The first draft of the 2020 code has been published on the NFPA site and it is open for public comment until August 30th. This was an unaccepted PI so the method to make a comment is not straight forward. The following is from an email from the NFPA telling me how to comment on a rejected PI.

To answer your questions regarding submitting a public comment on the rejected Public Inputs, you would first review the First Draft Report to locate the Public Input #s within the online document. The link to the First Draft Report is located at [url]www.nfpa.org/70next[/URL] Once you have the Public Input #s, you are ready to submit the public comments. The public comment process is very similar to the public input process in that the only difference is that you will need to add a related item (in your case it is the rejected public inputs.)

 

[kwired]

To me it defies logic to put a 20A (potential) load on a 15A branch -especially knowing the CB is only good for 80% ampacity to begin with.
Even though (hopefully) the CB will trip under overload we wouldn’t design other circuits like this, why should receptacles be any different?



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That logic is more valid when talking about 15/20/30 amp circuits.

What do you use for a receptacle for something that is on a 80 amp branch circuit? Probably something rated 100 amps in most instances. Is that wrong to do so, seems more wrong to use a 60 amp device and there likely isn't any choices in between 60 and 100 other then IEC 63 amp rating.

 

[infinity]

To me it defies logic to put a 20A (potential) load on a 15A branch -especially knowing the CB is only good for 80% ampacity to begin with.
Even though (hopefully) the CB will trip under overload we wouldn’t design other circuits like this, why should receptacles be any different?

The 80% rule does not apply to a single receptacle on a individual branch circuit unless the equipment is considered a continuous load. An individual branch circuit can be loaded to 100% of its rated ampacity.

210.22 Permissible Loads, Individual Branch Circuits.
An individual branch circuit shall be permitted to supply
any load for which it is rated, but in no case shall the load
exceed the branch-circuit ampere rating.

From the panel action on a rejected proposed (PI-2821)change to for the 2020 NEC that would have required single receptacles to comply with the values in Table 210.21(B)(3).

From panel statement:

Section 210.21(B)(1) clearly states that a single receptacle on an individual branch circuit shall have a rating of not less than that of the branch circuit. The present text is clear in this regard. Although an overload condition may occur and be cleared by the overcurrent protective device, a safety hazard is not present should a 30A receptacle be placed on a 20A circuit. Table 210.21(B)((3), as noted in 210.21(B)(3), is addressing two or more receptacles on a branch circuit and therefore is not in conflict with 210.21(B)(1) regarding single receptacles on an individual branch circuit. Manufacturer’s requirements would also apply per 110.3(B)

Thanks for digging that up Don. There is no reason why the single receptacle needs to limited to the size of the branch circuit as the CMP has correctly stated. If this somehow managed to get into the NEC then NEMA would need to come up with a 40 amp receptacle configuration and manufacturers would need to start making them, otherwise there will be no more 40 range circuits.

 

[Dale001289]

That logic is more valid when talking about 15/20/30 amp circuits.

What do you use for a receptacle for something that is on a 80 amp branch circuit? Probably something rated 100 amps in most instances. Is that wrong to do so, seems more wrong to use a 60 amp device and there likely isn't any choices in between 60 and 100 other then IEC 63 amp rating.

Correct; 80A (continuous) load requires a 100A CB - and 100A cable. In heavy industry we frequently put multiple 60A 480V receptacles on a single 100A branch CB where demand and diversity factors are predicted to be very high.
The same general reasoning seems to apply to a ‘non-continuous’ 20A receptacle and a 15A branch CB. As stated in many previous posts, NEC is not a design guide and provides minimal safety requirements.
I think experience and good design judgement should rule in each case.


Sent from my iPhone using Tapatalk

 

[Jamesco]

Don,
Thank you for your last post #42. I would call that Black and White.

.

Telling me that the single receptacle must have a rating at least equal to that of the branch circuit is very specifically telling me that I can install a receptacle with a rating that is greater than that of the branch circuit. A very common application of this is for industrial pin and sleeve receptacles. The very often exceed the rating of the branch circuit. In many cases there is not a receptacle that can be purchased that matches the rating of the branch circuit and to use one with a rating less than the branch circuit is a violation. One brand that I use has receptacles available in the following sizes, 20, 30, 60 and 150. We have to use the 150 amp rated ones for the 70 amp welder.

I agree with you on this one. Been there done that. In all fairness though you are giving an example of an industrial facility where qualified personnel are on duty. You are not dealing with the non qualified general public. If the plug fits it must be ok to use..... This thread has been about 15 amp and 20 amp individual branch circuits. My thoughts, responses, were meant in regards to residential and small commercial structures where a higher ampere rated receptacle is/maybe used on 15 and 20 amp individual branch circuits.

No one has said that you can do that. While there is no violation installing the larger rated single receptacle, there is a violation is connecting a load that exceeds that of the branch circuit.

Who is there to police the outlet after the electrician has been long gone. If the plug fits the receptacle, then it must be electrically safe to use. How many non professional people do know that knows more than just the basics of electrical circuits? If the plug fits.....

1875 watt hair dryers have 15 amp plugs.

Not quite the same as a piece of equipment rated for continuous duty. What do you think the FLA would be for a server with a 15 amp plug? My bet is 12 amps max. 20 amp plug, 16 amps max.

Just a guess a hair dryer falls under a different NEMA electrical safety standard, non continuous load. Though even at 1875 watts it still falls within 15 amps.

If you have one check the nameplate rating. Bet it says, 1875 watts @ 125Vac. 1875/125 = 15 amps.

There are no cases where the installation of the receptacle is a code violation. There may be case where using the receptacle at its rated load would be a code violation.

Yes there is a very good chance it will never trip at 16 or even 18 or 20 amps....so are you saying a single 15 amp receptacle on a 15 amp OCPD is not safe?

No I am not saying a single 15 amp receptacle installed on a 15 amp individual branch circuit is unsafe. I am saying a single 20 amp receptacle installed on a 15 amp individual branch circuit could be unsafe. Until this thread came along If I seen a single 20 amp receptacle I just assumed it was connected to a 20 amp branch circuit. Not so it turns out. A person can't even assume a single 30 amp receptacle is connect to a 30 amp individual branch circuit. By code it could be a 20 amp circuit or it could be a 15 amp circuit.

If the intended use, at the time of installation, has a load less than the rating of the branch circuit, there is no violation.

You collect your money for installing a 20 amp receptacle on a 15 amp circuit and walk out the door and never look back. Did you somehow permanently label the outlet saying "20 amp receptacle installed on a 15 amp individual branch circuit?" Code doesn't require it, therefore I doubt if there is any labeling ......

I am still trying to figure out why any electrician would install a 20 amp receptacle on a 15 amp circuit. Other than for a customer to plug in a 20 amp plug.

Best regards,
Jim

 

[Adamjamma]

The code doesn't say anything one way or the other if the receptacle rating for a single receptacle, installed an individual branch circuit, can be higher than the branch circuit rating. Because it doesn't say it the consensus of the majority that have posted on this thread say that makes it ok. Maybe the authors of the Code didn't think it was necessary to put it in black and white that it is not acceptable. Jmho, it's just common sense not to have the receptacle ampere rating higher than the branch circuit rating. It's not idiot proof. (Though in Table 210.21(B)(3) there is an exception to use a 40 or 50 amp receptacle on a 40 amp circuit. Just guessing it was tested by the manufacture and or UL, just a guess.)





Are there any sections in the code that would make it non compliant to install a higher ampere rated single receptacle than the individual branch circuit ampere rating? In other words, by installing the higher ampere rated receptacle are you inadvertently violating another section of the code?

A customer buys a new server to replace an old one. He discovers the plug on the new server will not plug into the existing individual branch circuit wall receptacle outlet. According to the majority that have posted on this thread all that needs to be done is to change out the receptacle to match that of the plug on the new server power cord. Code Compliant? Majority says, Code doesn't say he can't.

What determines the plug ampere rating that a manufacturer uses for a piece of equipment? Is there an electrical safety standards that dictates the NEMA plug the manufacturer must use for his piece of equipment? Can he use a NEMA 5-15P if his equipment FLA is 14 or 15 amps? Or does NEMA electrical safety standards dictate he must use a NEMA 5-20P? Why? It has to be idiot proof. A 5-20P plug will not physically fit, plug, into a 5-15R receptacle. IF the branch circuit is 20 amps the user can simply change the 15 amp receptacle to a 20 amp receptacle.


According to the majority that have posted on this thread if the branch circuit is an individual 15 amp branch the user can install a single 5-20R receptacle. Code does not specifically say he can't. Therefore it is code compliant. Is it? Doesn't that defeat the purpose the NEMA electrical safety standards configurations for plugs and receptacles ampere ratings? Are there any sections in the Code that may be in violation when the 5-20R is installed on the 15 amp branch circuit?

What if the FLA on the piece of equipment is 16 amps. Many that posted on this thread said no problem. Eventually the breaker will trip open. Guaranteed? Good chance it will never trip.
Any Code violations come to mind? Here's an easy one 210.22 Permissible Loads, Individual Branch Circuits. So if a single 20 amp receptacle is installed on the individual 15 amp branch circuit is the installation Code compliant? Yeah, according to many that have posted on this thread, but did you violate another section of the code when you installed it?


Best regards,
Jim

It is interesting following these arguments. Yes, there is the idea that the wiring may not hold up if something is plugged in that requires more than 20 amps, but, in actual fact, the 12 guage wire is supposed to be capable of 27 amps. The fuse is set for twenty. So, if all teh naysayers are to be believed, when I use 2.5 mm wire in a 15 amp lighting circuit instead of 1.5 wire, I am wrong. OR when I use 20 amp circuits to the kitchen and then the customer runs five blenders at one time but does not blow the breaker, something is wrong?
Personally, I see no problem running 20 amp outlets in the whole house. I would prefer to do that, just as I was installing grounded outlets since 1980... and never installed a two prong outlet. But, I am just a student, as all I did before now was handyman and was not actively trying to become an electrician.
Just wonder though, what would the average US electricians thoughts be on the UK outlets? Everything here is 13 amp outlets but they can actually handle 30 amps, in case the ring mains fails somehow.
But, all of our plugs here have fuses.
On an aside, based upon what some are saying, does that mean that if you wire a dedicated circuit for a fridge, you must use a single outlet recepticle?

 

[infinity]

No I am not saying a single 15 amp receptacle installed on a 15 amp individual branch circuit is unsafe. I am saying a single 20 amp receptacle installed on a 15 amp individual branch circuit could be unsafe. Until this thread came along If I seen a single 20 amp receptacle I just assumed it was connected to a 20 amp branch circuit. Not so it turns out. A person can't even assume a single 30 amp receptacle is connect to a 30 amp individual branch circuit. By code it could be a 20 amp circuit or it could be a 15 amp circuit.

Jim,

I agree with you in principle that when you see a 20 amp single receptacle one would assume that it's connected to a 20 amp branch circuit. As we've discussed in this thread according to the NEC it does not have to be. That's the code in black and white.
And from a safety standpoint I don't see it as unsafe. You can have 10 kitchen countertop receptacles on one circuit with many appliances plugged in at the same time, in fact it happens often that those circuits get overloaded and the OCPD does its job and trips. The oversized single receptacle scenario is not much different.

 

[mlnk]

Interesting discussion...but not practical. When inspectors sees a 20 amp single receptacle they want to see #12 wire with a 20 amp breaker...and for a 30 amp receptacle, they want to see #10 wire and a 30 amp breaker. If not they will red tag the job and will not be convinced otherwise.
remember national is overruled by state, state is overruled by AHJ.
This is logical because the end user sees the receptacle and assumes they can load it accordingly.
The 50 amp receptacle is another story.

 

[infinity]

Interesting discussion...but not practical. When inspectors sees a 20 amp single receptacle they want to see #12 wire with a 20 amp breaker...and for a 30 amp receptacle, they want to see #10 wire and a 30 amp breaker. If not they will red tag the job and will not be convinced otherwise.
remember national is overruled by state, state is overruled by AHJ.
This is logical because the end user sees the receptacle and assumes they can load it accordingly.
The 50 amp receptacle is another story.

That all depends on whether or not they enforce the NEC as written or they make up their own interpretation. The NEC wording is very clear on this one.

 

[tortuga]

20A breaker, #12 AWG conductors, dedicated 30A receptacle. It would seem the 20A breaker is protecting the wire and receptacle adequately.

210.24 implies that if I add multiple 30A receptacles to the circuit, and the load is still less than 16A non-continuous (or 20A continuous), then it is not legit. Is that your interpretation as well?

I think it depends on the equipment and the equipment's listing.
A common thing I see is a old NEMA 10-50 wired for an electric cloths dryer in older residential. Even houses around here built in the 70's and 80's typically have 8/3 with ground run to the 10-50 receptacle. The original electricians typically cut off the equipment ground when they wire it in and land it on a 2 pole 40. A quick fix would be to swap in a 2 pole 30 and leave the dryer plug as is (what I did at my house). However if you dig deeper the manufacturers instructions may call for a 30 A receptacle, (often there is a sticker right on the appliance) then per NEC 110.3(B) the 50A receptacle is not code compliant.

 

[sameguy]

I think it depends on the equipment and the equipment's listing.
A common thing I see is a old NEMA 10-50 wired for an electric cloths dryer in older residential. Even houses around here built in the 70's and 80's typically have 8/3 with ground run to the 10-50 receptacle. The original electricians typically cut off the equipment ground when they wire it in and land it on a 2 pole 40. A quick fix would be to swap in a 2 pole 30 and leave the dryer plug as is (what I did at my house). However if you dig deeper the manufacturers instructions may call for a 30 A receptacle, (often there is a sticker right on the appliance) then per NEC 110.3(B) the 50A receptacle is not code compliant.

I think it was Eagle brand where the 30a/50a recept. we're the same only the cover changed.

 

[augie47]

I think it was Eagle brand where the 30a/50a recept. we're the same only the cover changed.

same thing with their male plug. It came with a straight and L shaped prong,, just pick the one you need.

 

[LarryFine]

I think it was Eagle brand where the 30a/50a recept. we're the same only the cover changed.

Just like most receptacles: same conductive parts, different face-plate.

 

[jbelectric777]

code

code

if not elsewhere in the codebook - max OCPD shall be 30 amperes for awg10cu read the obelisk under the ampacity table... 12awg cannot serve for a dryer at 30 amps it needs a 10cu

 

[mwm1752]

While I completely agree the 20 amp breaker protects the 12# conductors going to the 30 amp receptacle and that we cannot be responsible for a professional electricians of home owner that may want to trade the 20 amp breaker to 30 amp in a non compliant action you have my attention. Soooo, I took a quick look at a 4 wire 30 amp receptacle to see if there may be a clue to non compliance -- yes they are rated 125/250 volts check but unless you pigtail that 12# with a 10# wire for connection to the terminal it is a violation of the listing. So, if I am inspecting such an unusual situation I better be sure the conductor in the termination is 10# -- do I get a fee now ?????

 

[kwired]

While I completely agree the 20 amp breaker protects the 12# conductors going to the 30 amp receptacle and that we cannot be responsible for a professional electricians of home owner that may want to trade the 20 amp breaker to 30 amp in a non compliant action you have my attention. Soooo, I took a quick look at a 4 wire 30 amp receptacle to see if there may be a clue to non compliance -- yes they are rated 125/250 volts check but unless you pigtail that 12# with a 10# wire for connection to the terminal it is a violation of the listing. So, if I am inspecting such an unusual situation I better be sure the conductor in the termination is 10# -- do I get a fee now ?????

I need to see the actual listing information before I will agree with that. Something tells me it won't say anything about conductor sizes other than as it relates to mechanical minimum and maximums.

 

[mwm1752]

I need to see the actual listing information before I will agree with that. Something tells me it won't say anything about conductor sizes other than as it relates to mechanical minimum and maximums.

It is on the receptacle yoke _ just google an image -- I am not saying all are as such but the first image shown had it stamped on the device --- now mt feeling are hurt

 

[mwm1752]

h

 

[kwired]

It is on the receptacle yoke _ just google an image -- I am not saying all are as such but the first image shown had it stamped on the device --- now mt feeling are hurt

That is the rating of the device, not the listing information.

Can you land 12 AWG conductors on a 30 amp switch? Even a 60 amp switch?

It might be somewhat rare you would land 12 AWG on a 30 amp receptacle, but I don't think it is prohibited either.