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#101285 - 03/02/07 08:22 PM Oversized Receptacle  
BigJohn  Offline
Member
Joined: Mar 2004
Posts: 391
Boston, MA
Here's the setup:

30A receptacle on #10 wire with a 20A breaker protecting it, non-residential setting.

I maintain this isn't legal per 210.19 and 210.23(A)(1). The idea being that a 30 amp receptacle, when used as designed, guarantees that the circuit will be overloaded.

Have several people that disagree with me, arguing that the tripping of the breaker negates the overload, swear that they have had this install pass inspection.

Opinions?

-John


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#101286 - 03/02/07 08:59 PM Re: Oversized Receptacle  
resqcapt19  Offline
Member
Joined: Nov 2000
Posts: 2,148
IL
John,
Assuming this is a single receptacle then it is permitted by 210.21(B)(1).
Quote
(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.

Don


Don(resqcapt19)

#101287 - 03/02/07 09:15 PM Re: Oversized Receptacle  
BigJohn  Offline
Member
Joined: Mar 2004
Posts: 391
Boston, MA
Don,

I saw that, but am I to interpret it to read that while I can never under-size a single receptacle, there's nothing to prohibit how large a receptacle you can put on a given circuit?

-John


#101288 - 03/02/07 11:49 PM Re: Oversized Receptacle  
George Little  Offline
Member
Joined: Jan 2004
Posts: 1,489
Michigan USA
John- I agree with Don. So if you install your 30a. single receptacle on a circuit rated for 15a. or 20a. you've not created a hazard but I don't see the advantage either.


George Little

#101289 - 03/03/07 01:43 AM Re: Oversized Receptacle  
resqcapt19  Offline
Member
Joined: Nov 2000
Posts: 2,148
IL
John,
Quote
I saw that, but am I to interpret it to read that while I can never under-size a single receptacle, there's nothing to prohibit how large a receptacle you can put on a given circuit?

Yes.
Don


Don(resqcapt19)

#101290 - 03/03/07 08:32 AM Re: Oversized Receptacle  
HLCbuild  Offline
Member
Joined: Dec 2004
Posts: 209
Herndon,Va USA
Table 210-21 (B)(3)is another example. For ranges and cooking appliances we use a 50 amp receptacle on a 40 amp circuit.


#101291 - 03/03/07 01:17 PM Re: Oversized Receptacle  
BigJohn  Offline
Member
Joined: Mar 2004
Posts: 391
Boston, MA
I didn't carefully read the articles I referenced earlier, and it appears neither of them applies.

While there doesn't seem to be anything directly prohibiting the oversize of a receptacle (and in some cases specifically allowing it), I don't understand how this doesn't violate 210.23 which supports my original argument(emphasis added):
Quote
Permissable 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 on 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.
Certainly if a piece of equipment has a 30A cord-cap there is the real possibility it will draw more than 20A. If someone were to plug it into the available 30A receptacle, it would exceed the rating of the 20A breaker causing it to trip. This violates 210.23, correct?

Is it the responsibility of the person owning the equipment to ensure that a circuit is capable of handling the load they impose on it? Even if the receptacle on the circuit is designed for the rating of their equipment, and this receptacle is the only load served?

Or is it the responsibility of the installing electrician to ensure that using his installation as designed does not invariably creat a code violation?

-John


#101292 - 03/03/07 04:55 PM Re: Oversized Receptacle  
George  Offline
Member
Joined: Feb 2002
Posts: 375
BigJohn ---

I agree with your reading. In general, 30amp recepts are not allowed on 20amp circuits.


#101293 - 03/03/07 05:20 PM Re: Oversized Receptacle  
caselec  Offline
Member
Joined: Apr 2002
Posts: 558
San Jose, CA
Installing a single receptacle with an amp rating larger that the circuit supplying it is clearly permitted. How is installing a single 30 amp receptacle on a 20 amp circuit any different than installing ten 15 amp receptacles in a 15 amp circuit? Either way the circuit can be overloaded by the loads plugged in.

How do you connect a piece of portable equipment that requires a 70 amp circuit? A 100 amp device is the only option.

Curt


Curt Swartz

#101294 - 03/05/07 12:19 PM Re: Oversized Receptacle  
George  Offline
Member
Joined: Feb 2002
Posts: 375
One hardwires the 70amp device. One does not use a 100amp plug.

---

One is required to comply with all of the sections of the code not just one.


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