# Is it legal to install a 250V 100A single receptacle on a individual 20A circuit



## Nicnac2400 (Nov 12, 2021)

Is it legal to install a 250V 100A single receptacle on a individual 20A circuit. From what I have read in code, section 210.21(B)(1) allow this. I can’t find a code rule this setup would break.

This is just a hypothetical question. Not something I would actually do do but was curious if anything in the code would prevent this type of installation.


----------



## Almost Retired (Sep 14, 2021)

IBTL !!!


----------



## Majewski (Jan 8, 2016)

can you put it in a sentence?


----------



## yankeejoe1141 (Jul 26, 2013)

Nicnac2400 said:


> but was curious if anything in the code would prevent this type of installation.


common sense


----------



## Majewski (Jan 8, 2016)

yankeejoe1141 said:


> common sense


that aint common at all!


----------



## yankeejoe1141 (Jul 26, 2013)

Majewski said:


> that aint common at all!


It never is!


----------



## Nicnac2400 (Nov 12, 2021)

yankeejoe1141 said:


> It never is!


Okay I can’t think of a good application of my hypothetical question. However lets say a customer tells you he has a 20A dedicated circuit for a specific piece of equipment and wants a noninterchangeable receptacle to make sure someone does not use the receptacle for other equipment. If you had a 100A rated receptacle/Cord cap sitting in your truck could you just install it and call it a day? Legal or not?


----------



## Majewski (Jan 8, 2016)

Nicnac2400 said:


> Okay I can’t think of a good application of my hypothetical question. However lets say a customer tells you he has a 20A dedicated circuit for a specific piece of equipment and wants a noninterchangeable receptacle to make sure someone does not use the receptacle for other equipment. If you had a 100A rated receptacle/Cord cap sitting in your truck could you just install it and call it a day? Legal or not?


idc what a customer tells me, im the pro.


----------



## yankeejoe1141 (Jul 26, 2013)

Nicnac2400 said:


> Okay I can’t think of a good application of my hypothetical question. However lets say a customer tells you he has a 20A dedicated circuit for a specific piece of equipment and wants a noninterchangeable receptacle to make sure someone does not use the receptacle for other equipment. If you had a 100A rated receptacle/Cord cap sitting in your truck could you just install it and call it a day? Legal or not?


Why not just a lockable disconnect instead of frankenstein’s bride?


----------



## J F Go (Mar 1, 2014)

You can do anything you want, just don't get caught. Is this the answer you were looking for ?


----------



## five.five-six (Apr 9, 2013)

I love this part of ET


----------



## Majewski (Jan 8, 2016)

five.five-six said:


> I love this part of ET


its grand aint it?


----------



## yankeejoe1141 (Jul 26, 2013)

Definitely not for the faint of heart at times!


----------



## WannabeTesla (Feb 24, 2020)

Like they used to say in the military right before they cut us loose in a strange port- you can do anything you want as long as you're willing to pay the price.

So the short answer is yes? My question is why? Joking aside, it's physically possible but what's the need? There are many hypotheticals that are competely legal only because they're not specifically prohibited, but these may not be conventional. This is kind of like the guy who puts truck tires on his Ford Probe.


----------



## splatz (May 23, 2015)




----------



## splatz (May 23, 2015)

Now there's no code rule about sticking your finger in whatever you do install, so feel free.


----------



## gpop (May 14, 2018)

You will on occasions come across something like you are describing. There is no real safety issue on the receptacle side because if you plugged in a 240v 100 amp load it would simply clear the breaker but there would be a huge safety issue according to code on the plug side. 
If a customer asked for 20 amp 120v receptacle that was designed to stop anything else being plugged into it then a 20 amp twist lock would be the simple solution.


----------



## WannabeTesla (Feb 24, 2020)

splatz said:


> View attachment 160872


I forgot about this. Back to the book i go...


----------



## Majewski (Jan 8, 2016)

splatz said:


> Now there's no code rule about sticking your finger in whatever you do install, so feel free.


not true.......110 3b


----------



## 205490 (Jun 23, 2020)

What? Why? Oh wait, I see ....its on the truck.
Gosh I love this forum 🤣


----------



## Wirenuting (Sep 12, 2010)

WannabeTesla said:


> Like they used to say in the military right before they cut us loose in a strange port- you can do anything you want as long as you're willing to pay the price.


When we pulled in they told us we could do anything we wanted, just don’t miss the ship when she leaves. 

Only once did I ride a water taxi back to the ship while she was blowing the recall whistle and I watched as the anchor was being pulled up. That was a bad feeling. But hey, I made it back before she got underway and 1/2 the crew didn’t.


----------



## taglicious (Feb 8, 2020)

What AWG is there? Or are you just doing a service call and trying to make a judgement call saying ‘sure I can do that while I’m here’


----------



## Majewski (Jan 8, 2016)

careful not to make the buildings fall over


----------



## Nicnac2400 (Nov 12, 2021)

WannabeTesla said:


> I forgot about this. Back to the book i go...


That table does not apply to a single dedicated receptacle


----------



## Nicnac2400 (Nov 12, 2021)

taglicious said:


> What AWG is there? Or are you just doing a service call and trying to make a judgement call saying ‘sure I can do that while I’m here’


This question is totally hypothetical. I was casually reading basic code rules and realized the code is very specific in table 210.21(B)(3) with defined rating of a branch circuit for multi receptacle circuits up to 50 amps. However after shortly thinking about it single receptacles do not have rules that govern their minimum circuit ratings (where my hypothetical question stems from). I was wondering about why they would go out of their way to address branch circuit ratings in relation to receptacle ratings in 210.21(B)(3) with A table and leave it to common sense in 210.21(B)(1).
I thought maybe I missed something somewhere else in the code that would prevent the type of installation that i described but after a little more looking i determined it would be legal. 
One other thing while looking. What is the deal with 25A branch circuits feeding two or more receptacles according to my interpretation of 210.21(B)(3) the table would not apply to the circuit. (Again this is all hypothetical I will use what little common sense I have in practice lol)


----------



## mburtis (Sep 1, 2018)

Personally I can't see a safety issue with putting a higher rated receptacle in a lower rated circuit. My way of thinking is that the breaker is there to protect the wire inside the wall and the receptacle. So as long as the wire and the receptacle can handle 20 amps who cares what they plug in. Now it may not be a good idea, because someone in the future will see the plug and think they can plug there big behemoth welder or spa or something into it. Of coarse the breaker will trip and dash their dreams. If an unknowing person just switches out the breaker without evaluating the wire then well, break out the marshmallows and make some smores.


----------



## Nicnac2400 (Nov 12, 2021)

mburtis said:


> Personally I can't see a safety issue with putting a higher rated receptacle in a lower rated circuit. My way of thinking is that the breaker is there to protect the wire inside the wall and the receptacle. So as long as the wire and the receptacle can handle 20 amps who cares what they plug in. Now it may not be a good idea, because someone in the future will see the plug and think they can plug there big behemoth welder or spa or something into it. Of coarse the breaker will trip and dash their dreams. If an unknowing person just switches out the breaker without evaluating the wire then well, break out the marshmallows and make some smores.


Thats what I was thinking, and if all we are worried about is the wire in the wall then what is the point of table 210.21(B)(3).


----------



## mburtis (Sep 1, 2018)

Other than allowing 15 amp receptacles on 20 circuits, I have no idea. Seems they could have just said receptacle ratings must match circuit ampacity.


----------



## WannabeTesla (Feb 24, 2020)

Nicnac2400 said:


> Thats what I was thinking, and if all we are worried about is the wire in the wall then what is the point of table 210.21(B)(3).


Not trying to be cheeky- i wonder if it's a safety layer on account of possible breaker failure/ malfunction.


----------



## Nicnac2400 (Nov 12, 2021)

WannabeTesla said:


> Not trying to be cheeky- i wonder if it's a safety layer on account of possible breaker failure/ malfunction.


I would agree with it being a safety layer to protect to prevent relying on the breaker to protect the circuit breaker. but then why would you have no such table for single receptacles on a circuit.


----------



## kb1jb1 (Nov 11, 2017)

I find hypothetical questions a time consuming activity that goes round and round and gets people confused. Do the right thing and avoid confusion in the present and in the future. Ten years down the road,, after the place is sold, someone might come along and think they have a 100 amp outlet for their EV. Like selling a house with a fireplace but no chimney. Or a dishwasher with no drain. You won't find tables or charts but you will find the wiring has to match the device or equipment somewhere in the NEC verbiage.


----------



## readydave8 (Sep 20, 2009)

it may not be desirable, but I suspect it's legal


----------



## HertzHound (Jan 22, 2019)

*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.

Why wouldn’t this apply? You have a 20 amp circuit but the load could could be up to 100 amps because of the receptacle configuration.


----------



## splatz (May 23, 2015)

HertzHound said:


> *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.
> 
> Why wouldn’t this apply? You have a 20 amp circuit but the load could could be up to 100 amps because of the receptacle configuration.


I guess it comes down to a silly idea of what the words "but in no case shall the load..." mean. To me, the load of a receptacle, even an individual branch circuit receptacle, is any compliant utilization equipment someone may come along and plug in at any future date. But, evidently the code takes the view that "the load" is the load imposed by the utilization equipment that was in my mind's eye when I installed it, which could be some goofball thing with an oversized cord and plug, a 5 amp device with a 100 amp cord and plug. 

I also think that 210.21(B)(3) should apply to individual branch circuits, with the exceptions in the table, but it doesn't.


----------



## splatz (May 23, 2015)

A number of posts mention the principle that the breaker protects the wire, which is true, the breaker is set up to protect the wire, not the utilization equipment, the utilization equipment is expected to have wires sized for it's load etc. 

Another principle, more a common sense principle that I don't think is in the code (although maybe it should be): If nobody does anything stupid, and there are no faults present, breakers should not be tripped. 

Plugging 100A load utilization equipment with a 100A cord and plug into a 100A receptacle is not doing something stupid. I shouldn't have to somehow know what was in the mind's eye of the installer when they wired that receptacle for a 20A breaker and wire for a goofball 15A device with a 100A cord and plug, and rely on the breaker tripping to prevent a fire.


----------



## cutlerhammer (Aug 16, 2011)

Nicnac2400 said:


> Is it legal to install a 250V 100A single receptacle on a individual 20A circuit. From what I have read in code, section 210.21(B)(1) allow this. I can’t find a code rule this setup would break.
> 
> This is just a hypothetical question. Not something I would actually do do but was curious if anything in the code would prevent this type of installation.


If you can't see it from my house, go ahead!


----------



## yankeejoe1141 (Jul 26, 2013)

cutlerhammer said:


> If you can't see it from my house, go ahead!


Maybe it’s better if you CAN see it from your house… then you can drop off your card and offer to do it right!


----------



## gpop (May 14, 2018)

After thinking about this a little bit more. If the plug/receptacle stats "100 Ampere Current Rating" then its not technically a 100 amp plug its just a plug that's rated up to 100 amp.


----------



## Nicnac2400 (Nov 12, 2021)

gpop said:


> After thinking about this a little bit more. If the plug/receptacle stats "100 Ampere Current Rating" then its not technically a 100 amp plug its just a plug that's rated up to 100 amp.


I agree with that. But my issue with the code is that if you have 1 100A receptacle on the 20A circuit it is acceptable as a plug rated 100A.
However if you have 2 100A receptacle on the 20A circuit it is illegal (NEC 210.21(B)(3)).
Now my issue is that both instances essentially give you the same outcome. At first i kind of took it as a loophole in the code. However with how direct NEC 210.21(B) is it almost seems like they went out of their way to create this “loophole”


----------



## R777V (May 16, 2016)

In our Data Center IBM spec’d the craziest **** huge oversized cables huge Russell Stowe’s connectors and the machines would pull like 20-30 amps max never more. They were on 100 amp circuits. I seem to remember some legacy Xerox equipment “overwired” in a similar fashion. Like they were planning for it to make it thru the Apocalypse. Maybe just because they could?


Sent from my iPhone using Tapatalk


----------

