Changing 20A plug to a 50A plug in order to use a 50A receptacle?

[Gary386]

If I have a 20A device, with a 20A plug, is there any reason I can't change it to a 50A plug and use it on a 50A circuit?

In the extreme case, could I wire a clock (very low amperage) to a 50A plug and use it on a 50A circuit?
If the answer is no, then how is it OK for an electric range with a 50A plug run the built-in clock?

I know that it is OK to run a very low amperage night light on a 20A circuit. I understand that neither the night light nor clock in my examples are protected by the circuit breaker, but is this against code?

 

[roger]

Spend a little time in Part II of article 210, specifically Table 210.21(B)(3). The clock that is part of the range in your example is not an NEC issue, it is part of a listed assembly.

Roger

 

[jumper]

Is your device/equipment UL listed for this application? Therein lies the key. The clock on the stove and the night light have UL approval/listing.

Roger beat me by a minute.

 

[north star]

~ + ~ +

Tsk, ...tsk, ...tsk!
Gentlemen please, ...let us extend a warm and hearty welcome to a
Junior member, who has chosen to come here for answers........Welcome
" Gary386 " to this Forum! :happyyes:

+ ~ + ~

 

[roger]

~ + ~ +

Tsk, ...tsk, ...tsk!
Gentlemen please, ...let us extend a warm and hearty welcome to a
Junior member, who has chosen to come here for answers........Welcome
" Gary386 " to this Forum! :happyyes:

+ ~ + ~

Hmmmm ok, please see posts 2 and 3 for answers.

Roger

 

[jumper]

~ + ~ +

Tsk, ...tsk, ...tsk!
Gentlemen please, ...let us extend a warm and hearty welcome to a
Junior member, who has chosen to come here for answers........Welcome
" Gary386 " to this Forum! :happyyes:

+ ~ + ~

You are correct, but I still doubt OPer can do what he intends until further info is supplied.

Oh yeah, I forgot:

Welcome and I mean it.

 

[Gary386]

Roger and Jumper,

Thanks for your prompt response.

I have spent more than a little time reviewing Table 210.21(B)(3) and think I understand it. I know that a 50A receptacle is required on a 50A circuit. The question is "Can I put a 50A plug on any device that I want to (assuming that it requires less than 50A), and use it on a 50A circuit?"

A 30A device with UL listing may come with a 30A plug. Am I violating anything if I remove that plug and replace it with a 50A plug and use it on a 50A circuit? Does the fact that it is UL listed change anything?

P.S. Thanks for the warm welcome. I will try to behave myself. I am an electrical engineer, but I am not a professional engineer nor an electrician. I will try to remember that "A little knowledge is a dangerous thing".

 

[jumper]

A 30A device with UL listing may come with a 30A plug. Am I violating anything if I remove that plug and replace it with a 50A plug and use it on a 50A circuit? Does the fact that it is UL listed change anything

Yes, the inspector need not accept it. You have to protect the equipment at its listed max or calculated OCPD.

240.3 Other Articles. Equipment shall be protected against
overcurrent in accordance with the article in this Code that
covers the type of equipment specified in Table 240.3.

 

[petersonra]

Roger and Jumper,

Thanks for your prompt response.

I have spent more than a little time reviewing Table 210.21(B)(3) and think I understand it. I know that a 50A receptacle is required on a 50A circuit. The question is "Can I put a 50A plug on any device that I want to (assuming that it requires less than 50A), and use it on a 50A circuit?"

Of course you can. There may or may not be some safety issues involved, but you can do it and it would work.

A 30A device with UL listing may come with a 30A plug. Am I violating anything if I remove that plug and replace it with a 50A plug and use it on a 50A circuit? Does the fact that it is UL listed change anything?

Whether or not it is UL listed does not seem to me to figure into the equation at all. I am not sure just what you would be violating. It certainly would not be in accordance with the manufacturer's instructions but a device that is plug and cord connected like this is not a device directly subject to the NEC, any more than a toaster is. The outlet the toaster plugs into is subject to NEC whims, but not the toaster itself.

There may or may not be safety issues associated with doing something like this. Realistically, the chance of this going bad on you is very low.

If your situation involves OSHA, you may have some issues with them. In a very legalistic sense what you are doing probably is a violation of something. It is probably not in and of itself "unsafe". The worst argument I can come up with is that it is slightly possible that the cord set that came with the clock is lightweight enough that it might not trip the 50A CB protecting this branch circuit if the cord or the clock were to short circuit and that might eventually lead to a fire due to overheating of the cord. How likely such a thing is, I don't know. Seems pretty low on the totem pole of things to worry about.

There might also potentially be an issue with the cord conductor size not mating up well with the new 50A plug that might cause some kind of problem.

There are probably ways that this can be accomplished that would not involve doing so in a suspect way, and in an environment subject to potential OSHA inspections, I would be looking to do so.

Incidentally, the circuit breakers are there to protect the premises wiring, not whatever is plugged into an outlet.

One thing I would suggest is that you are being very vague about what it is you actually want to do and that makes all of us a little nervous in the first place.

 

[petersonra]

Yes, the inspector need not accept it. You have to protect the equipment at its listed max or calculated OCPD.

240.3 Other Articles. Equipment shall be protected against
overcurrent in accordance with the article in this Code that
covers the type of equipment specified in Table 240.3.

I guess you could call it an appliance and thus subject to art 422.

422.11 Overcurrent Protection. Appliances shall be protected
against overcurrent in accordance with 422.11(A)
through 422.11(G) and 422.10.
(A) Branch-Circuit Overcurrent Protection. Branch circuits
shall be protected in accordance with 240.4.
If a protective device rating is marked on an appliance,
the branch-circuit overcurrent device rating shall not exceed
the protective device rating marked on the appliance.

So if it is marked on the appliance with a max Bc OCPD, you would be in violation of this section. I can't ever recall seeing such a marking.

However, the best argument for a code violation appears to come from 422.11(E) for the clock example. Although some might consider it a motor operated appliance.

(E) Single Non–motor-Operated Appliance. If the branch
circuit supplies a single non–motor-operated appliance, the
rating of overcurrent protection shall:
(1) Not exceed that marked on the appliance.
(2) Not exceed 20 amperes if the overcurrent protection rating
is not marked and the appliance is rated 13.3 amperes
or less; or
(3) Not exceed 150 percent of the appliance rated current if
the overcurrent protection rating is not marked and the
appliance is rated over 13.3 amperes. Where 150 percent
of the appliance rating does not correspond to a standard
overcurrent device ampere rating, the next higher standard
rating shall be permitted.

This would of course be contingent on the device in question being a "non-motor operated appliance".

 

[kwired]

Of course you can. There may or may not be some safety issues involved, but you can do it and it would work.


Whether or not it is UL listed does not seem to me to figure into the equation at all. I am not sure just what you would be violating. It certainly would not be in accordance with the manufacturer's instructions but a device that is plug and cord connected like this is not a device directly subject to the NEC, any more than a toaster is. The outlet the toaster plugs into is subject to NEC whims, but not the toaster itself.

There may or may not be safety issues associated with doing something like this. Realistically, the chance of this going bad on you is very low.

If your situation involves OSHA, you may have some issues with them. In a very legalistic sense what you are doing probably is a violation of something. It is probably not in and of itself "unsafe". The worst argument I can come up with is that it is slightly possible that the cord set that came with the clock is lightweight enough that it might not trip the 50A CB protecting this branch circuit if the cord or the clock were to short circuit and that might eventually lead to a fire due to overheating of the cord. How likely such a thing is, I don't know. Seems pretty low on the totem pole of things to worry about.

There might also potentially be an issue with the cord conductor size not mating up well with the new 50A plug that might cause some kind of problem.

There are probably ways that this can be accomplished that would not involve doing so in a suspect way, and in an environment subject to potential OSHA inspections, I would be looking to do so.

Incidentally, the circuit breakers are there to protect the premises wiring, not whatever is plugged into an outlet.

One thing I would suggest is that you are being very vague about what it is you actually want to do and that makes all of us a little nervous in the first place.

You have some valid points there.

Lets look at some places where this is allowed - lighting circuits. You can have 30 or 50 amp lighting circuits with 15 amp receptacles and 15 amp flexible cords to the supplied luminaires in some instances. (see 410.62(C))

You don't want to know how many 50 amp "welder" receptacles I run into that someone has either made an adapter cord or changed the end on a piece of equipment so it will plug into the "220 outlet" when the equipment they have would be suitable on a 15 or 20 amp circuit. There is rarely any incident with this but does not make it the right thing to do either.

 

[jumper]

You guys are killing my argument:rant:.....

 

[templdl]

Greetings Gary,

Think of it this way,
You have a circuit rated for 50A so the circuit is wired to serve that load. Then the breaker protects the wire.
Breakers are not intended to protect the load connected to the outlet no matter how small the load is just the wire to the outlet.
I guess in theory the small load could be sort of considered a tap in that the wire from the outlet to the load (I.E. Clock) is protected and not exposed to overload or being damaged. As such does it need to have overload protection? If so one would add supplimentary protection such as a suplimentrary circuit breaker (a UL1077 listed device) or a fuse for that purpose.

 

[Gary386]

Peter,

I don't want to make anyone nervous by being vague. The reason for my post is to understand the code better, rather than to determine a plan of action for an immediate problem. I guess that is another way of saying that the question in academic. For that reason, I stated the question in general terms, as straight forward and as simply as I could. If that is out of order for this forum, I sincerely apologize.

This question was posted on a woodworker's forum that I often visit. Some seemingly knowledgeable people had some very different (and strong) views. I didn't want to get involved, so I posted the question on this forum. I figured that this forum would be a better place for this topic.

Again, I hope that I'm not out of line. I don't want to insult or offend anyone. I just think that this topic is of general interest to members of this forum, and I will learn something.

Gary

 

[jumper]

Peter,

I don't want to make anyone nervous by being vague. The reason for my post is to understand the code better, rather than to determine a plan of action for an immediate problem. I guess that is another way of saying that the question in academic. For that reason, I stated the question in general terms, as straight forward and as simply as I could. If that is out of order for this forum, I sincerely apologize.

This question was posted on a woodworker's forum that I often visit. Some seemingly knowledgeable people had some very different (and strong) views. I didn't want to get involved, so I posted the question on this forum. I figured that this forum would be a better place for this topic.

Again, I hope that I'm not out of line. I don't want to insult or offend anyone. I just think that this topic is of general interest to members of this forum, and I will learn something.

Gary

You are not out of line by any means. This is just getting interesting/fun.

 

[kwired]

Peter,

I don't want to make anyone nervous by being vague. The reason for my post is to understand the code better, rather than to determine a plan of action for an immediate problem. I guess that is another way of saying that the question in academic. For that reason, I stated the question in general terms, as straight forward and as simply as I could. If that is out of order for this forum, I sincerely apologize.

This question was posted on a woodworker's forum that I often visit. Some seemingly knowledgeable people had some very different (and strong) views. I didn't want to get involved, so I posted the question on this forum. I figured that this forum would be a better place for this topic.

Again, I hope that I'm not out of line. I don't want to insult or offend anyone. I just think that this topic is of general interest to members of this forum, and I will learn something.

Gary

I don't think what you are talking about is a NEC issue if you are replacing a cord cap on a piece of equipment that was NRTL listed with a cord cap on it. You are tampering with the NRTL listing.

A piece of equipment listed without a cord cap may still be allowed to be cord and plug connected, but then NEC may apply as you are installing the cord cap - there could be instructions included with the listing that specify what cord caps are acceptable.

It all depends to some extent on what the equipment is. If motors are involved - higher level overcurrent devices than conductor ampacity are common to allow motor starting - overload protection is still provided by a motor overload device and short circuit and ground fault protection are still provided by branch circuit device.

There is not a minimum size issue with the size of receptacle or cord cap, there may be an issue with maximum overcurrent protection level of supplied equipment.

 

[petersonra]

It is hard to give specific answers to non-specific questions sometimes because the answers can vary so widely.

It is usually best to ask a vary specific question and provide as much information as possible about the circumstances. That will give you the best chance of getting a useful answer.

 

[fmtjfw]

You just can't plug it in

You just can't plug it in

210.23 Permissible Loads. In no case shall the load exceed
the branch-circuit ampere rating. An individual branch
circuit shall be permitted to supply any load for which it is
rated. A branch circuit supplying two or more outlets or
receptacles shall supply only the loads specified according
to its size as specified in 210.23(A) through (D) and as
summarized in 210.24 and Table 210.24.

....

(C) 40- and 50-Ampere Branch Circuits. A 40- or 50-
ampere branch circuit shall be permitted to supply cooking
appliances that are fastened in place in any occupancy.
In other than dwelling units, such circuits shall be
permitted to supply fixed lighting units with heavy-duty lampholders,
infrared heating units, or other utilization equipment.

 

[tom baker]

Please remember that for most cases, the NEC is for premise wiring, and is not typically concerned with what you plug into a receptacle. Appliances and such are covered by listing and product standards, but there is a correlation between the NEC/premise and appliances/listing. For example, an appliance intended for a 20 A branch circuit will be designed with internal wiring to withstand an short circuit or overload based 20A wiring.

 

[hurk27]

Please remember that for most cases, the NEC is for premise wiring, and is not typically concerned with what you plug into a receptacle. Appliances and such are covered by listing and product standards, but there is a correlation between the NEC/premise and appliances/listing. For example, an appliance intended for a 20 A branch circuit will be designed with internal wiring to withstand an short circuit or overload based 20A wiring.

My sediments exactly, we must remember that when manufactures design the appliance it is design to be used on a certain size circuit hence this limit by the cord and plug supplied with it, when we modify the cord so that it can be plugged into a larger circuit then we are altering the design that may or may not have a UL blessing on it, now if a fire or injury was to happen we could be found liable and subject to this even criminally if someone were to be killed by our actions.

I have posted many times on here that most fires are caused by what people plug in, and use cheap lamp cords as an example that can cause fires and shock hazards, but these cords to a small lamp will be protected by the virtue of the limit of the size of the load that can be connected to it, in most cases the lamp will only have one medium base holder and this protects the cord by this limitation of load, but there are those cheap lamp cord extension cords that leave it up to the person using it to limit the load, and we know this doesn't always happen as we see the results in the fires they cause, but the code can not always protect against this type of abuse, but we must remember, if we do it, we are looked upon to know better and with that can be liable if something was to go wrong.

So in essences: in no way would I change the design of an appliance that was design to be used on a lower current circuit so that it could be used on a higher amperage circuit, I would never risk my livelihood like this.

Oh and Welcome to the forum:thumbsup: