15A recep on 20A circuit - commercial vs residential

[tallgirl]

No he won't he will go to the local grocery store and buy one of those surge thingy's and plug six or seven more items into it.

And then he'll plug an extension cord into THAT, and yet another power strip.

I used to do fire and electrical safety talks to other collective members. You won't believe how often I've seen extension cord -> power strip -> extension cord -> power strip.

Oh, and a coffee machine on the end of the entire mess. Wouldn't be the same without the coffee machine.

 

[don_resqcapt19]

I think the code should only allow 20amp single receptacles for a dedicated circuit so it cant be overloaded. 20amp duplex receptacles cause A lot of problems because of this.

A properly installed overloaded circuit is a design issue not a safety issue. There is no reason for a new code rule.
Don

 

[charlie b]

Well, yes it is a safety issue. But it is not one of the safety issues that falls within the scope of the NEC.

 

[charlie b]

Reason for the question...An inspector in Michigan is saying that 210.11(C)(1) & (C)(2) requires the 20 Amp receptacle ratings in the Kitchen and Laundry room.

The inspector is wrong. Each of those articles is speaking about the branch circuit. What is required is a 20 amp branch circuit. The rating of the branch circuit is determined by the rating of the overcurrent device, not the loads. So if you use a 20 amp breaker, and if you use wire that is acceptable for a 20 amp circuit, then you have met the requirements of those two articles.

Now, if you want to know about the requirements related to the receptacles, then read (and tell the inspector to read) those two articles again more closely. Both speak of the receptacles that are required by other articles, namely 210.52(B) and 210.52(F). If you then flip over to those two sections, you will see that neither one states that you must use 20 amp receptacles.

 

[iwire]

A properly installed overloaded circuit is a design issue not a safety issue. There is no reason for a new code rule.

Well, yes it is a safety issue.

I have to disagree, if it was a safety issue every circuit would have to have only one receptacle installed on it.

It is IMHO strictly a design issue.

Any GP receptacle circuit is likely to be overloaded at some point.

 

[charlie b]

I think we are talking apples and baseball caps. What I was saying is that if I design, and you install, and Larry inspects and approves, a completely code-compliant system, and if the homeowner then overloads a receptacle circuit by plugging the world into it, then it is a safety issue. It is a safety issue caused by the user, and the NEC has little, if anything, to say about the conduct of the user.

 

[ryan_618]

If the circuit has an overload and the breaker trips, where is the safety concern? It sounds like a convienance (design) issue to me.

 

[winnie]

This hits on a topic that I've been confused about for a long time.

Many areas of code require OCPD rated at 125% of the load.

Is this a safety issue or a design issue?

What happens (beyond not being to code) if I design a system where all of the breakers are 100% loaded with long duration continuous loads.

Do I get 'nusiance tripping', or do I have a safety issue? If a user loads a general purpose 20A circuit so that the load is 20A continuous, does this have the potential for damaging the breaker, or will it simply cause the breaker to trip?

-Jon

 

[don_resqcapt19]

Frank,

I think the code should only allow 20amp single receptacles for a dedicated circuit so it cant be overloaded. 20amp duplex receptacles cause A lot of problems because of this.

That is a design issue not a code (safety) issue. There is no hazard in a correctly installed circuit if it is overloaded.
Don

 

[don_resqcapt19]

donniet,

An inspector in Michigan is saying that 210.11(C)(1) & (C)(2) requires the 20 Amp receptacle ratings in the Kitchen and Laundry room.

That code section does not say anything about the rating of the receptacles...it only specifies the rating of the branch circuit that supplies the receptacles. The rating of the receptacles is covered by 210.21(B)(3).
Don

 

[charlie b]

If the circuit has an overload and the breaker trips, where is the safety concern?

A 20 amp breaker that serves five 15 amp duplex receptacles can sustain a load of 22 amps for a very long time. If all of that 22 amps is being drawn from a single receptacle into which the HO has plugged a host of plug strips, extension cords, and heating lamps, then it is possible that a fire might be started before the breaker trips. It might happen in the overloaded 15 amp receptacle, or it might happen in one of the cords. That is the safety concern. But whose fault would that be? The homeowner, that's who. Not the EC, and not the Inspector, and indeed nobody whose work is governed by the NEC. That's all I am saying.

 

[don_resqcapt19]

Charlie,

It might happen in the overloaded 15 amp receptacle,

The only difference between the 15 and 20 amp receptacles of the same series and manufacture is the openings in the face. The guts are the same, so that is not a real safety issue cause by the use of 15 amp devices on a 20 amp circuit.
Don

 

[DesertRat]

This hits on a topic that I've been confused about for a long time.

Many areas of code require OCPD rated at 125% of the load.

Is this a safety issue or a design issue?

What happens (beyond not being to code) if I design a system where all of the breakers are 100% loaded with long duration continuous loads.

Do I get 'nusiance tripping', or do I have a safety issue? If a user loads a general purpose 20A circuit so that the load is 20A continuous, does this have the potential for damaging the breaker, or will it simply cause the breaker to trip?

-Jon

In a way you answer your own question. When code requires the OCPD be rated at 125% of the load, it essentially means that the load can only be 80% of the OCPD rating. If you have loaded said circuit to 100% of the OCPD rating, you have a code violation.

Note I say you, the electrician / designer / engineer... whomever you may be. The customer still has the ability to overload any circuit they want and the NEC has no say in the matter. But, when the homeowner does so, the OCPD trips, which is after all, what it is designed to do. a tripped OCPD = a dead circuit, and there is nothing electrically hazardous in that.

As to "full" loading, I've loaded many lighting panels with 20 amp breakers protecting 16 amp loads on a continuous basis. That is a pretty common occurance in the retail environment. Worst I've seen out of that scenario is maybe a slightly higher ambient temperature of the breakers (when compared to one with no load on it.)

 

[Mike03a3]

There seems to be general agreement that there is no issue using 15a receptacles on a 20a circuit (as long as there is more than one). UL investigates and lists 15a duplex receptacles for this usage.

Many also agree that a switch need only be rated for its load, and thus a 15a snap switch can also be used on a 20a circuit.

This makes sense to me when the loads being switched are known, as in the case of an installed luminaire. But what about a snap switch being used to switch receptacles? Shouldn't it be rated for the same load as the circuit being switched?