Branch circuit overcurrent definition

[brother]

I dont like the 'new definition' of 'Branch circuit overcurrent device'. NEC 2008 article 100 definitions. I believe its not enough a little too broad. Reason, actually had a debate with a guy that was installing an 'appliance' that say maxium overcurrent rating of 15 amps.

I told him this is the branch circuit over current device that has to be the '15 amps' . He claims he can put a inline fuse in after the 20 amp breaker, and that would be the branch circuit overcurrent device. I disagreed, but I do not believe the definition would support my stance. Only case I got is that it can have no 'interupting rating less than 5,000 ampers.

Am I wrong in this?? what is your opinion on this definition??

 

[mcclary's electrical]

IMO 422.11 (E) 3 permits him to do this WITHOUT the fuse. as is.

 

[jeremysterling]

I dont like the 'new definition' of 'Branch circuit overcurrent device'. NEC 2008 article 100 definitions. I believe its not enough a little too broad. Reason, actually had a debate with a guy that was installing an 'appliance' that say maxium overcurrent rating of 15 amps.

I told him this is the branch circuit over current device that has to be the '15 amps' . He claims he can put a inline fuse in after the 20 amp breaker, and that would be the branch circuit overcurrent device. I disagreed, but I do not believe the definition would support my stance. Only case I got is that it can have no 'interupting rating less than 5,000 ampers.

Am I wrong in this?? what is your opinion on this definition??

If he installs the inline fuse, your "branch circuit" just became his "feeder".

 

[don_resqcapt19]

Many inline fuses are not suitable for use as a branch circuit OCPD. You will have to check the listing of the fuse and fuse holder.

 

[brother]

IMO 422.11 (E) 3 permits him to do this WITHOUT the fuse. as is.

I dont see that. can you explain?? the face plate on the appliance says 'maximum overcurrent of 15 amps. So he is limited to 15 amps!! and I agree don_resqcapt19 alot of inline fuses are NOT rated for branch circuit overcurrent devices. Do you know of any??

 

[charlie b]

I think you need to back up a few paragraphs, within article 100. Start with "Branch Circuit," not with "Branch Circuit Overprotection Device."

If I understand the situation correctly (no guarantee of that! ) , we have a 20 amp circuit breaker at the panel, a pair of #12 (or larger) conductors, a standard (15 or 20 amp) receptacle outlet, and a plug & cord connected appliance, and "this guy" is proposing putting a fuse somewhere within the cord (i.e., between the receptacle and the appliance). Is that right?

If that is right, then the in-line fuse (whether or not rated as a branch circuit OCPD) does not establish the beginning of a branch circuit, and the wires upstream (i.e., up to the receptacle, and from the receptacle back to the panel) have not been re-designated as a feeder. The article 100 definition of a branch circuit ends at an outlet. In this example, the receptacle is that outlet. The in-line fuse holder is not an outlet, because it is not part of the premises wiring system.

So you cannot plug this appliance into a receptacle outlet that is fed from a 20 amp branch circuit, because their is a protective limit marked on the appliance. Reference 422.11(A). You are right, and the other guy is wrong.

 

[Smart $]

... Reference 422.11(A). You are right, and the other guy is wrong.

Additionally...

240.10 Supplementary Overcurrent Protection. Where
supplementary overcurrent protection is used for luminaires,
appliances, and other equipment or for internal circuits
and components of equipment, it shall not be used as
a substitute for required branch-circuit overcurrent devices
or in place of the required branch-circuit protection.
Supplementary overcurrent devices shall not be required to
be readily accessible.

 

[steve66]

I think you need to back up a few paragraphs, within article 100. Start with "Branch Circuit," not with "Branch Circuit Overprotection Device."

If I understand the situation correctly (no guarantee of that! ) , we have a 20 amp circuit breaker at the panel, a pair of #12 (or larger) conductors, a standard (15 or 20 amp) receptacle outlet, and a plug & cord connected appliance, and "this guy" is proposing putting a fuse somewhere within the cord (i.e., between the receptacle and the appliance). Is that right?

If that is right, then the in-line fuse (whether or not rated as a branch circuit OCPD) does not establish the beginning of a branch circuit, and the wires upstream (i.e., up to the receptacle, and from the receptacle back to the panel) have not been re-designated as a feeder. The article 100 definition of a branch circuit ends at an outlet. In this example, the receptacle is that outlet. The in-line fuse holder is not an outlet, because it is not part of the premises wiring system.

So you cannot plug this appliance into a receptacle outlet that is fed from a 20 amp branch circuit, because their is a protective limit marked on the appliance. Reference 422.11(A). You are right, and the other guy is wrong.

According to the definition of a branch circuit, it starts at the final overcurrent protection device. If you stick a fuse in a branch circuit, IMO, you have started a new branch circuit.

The only issue I see is that if your branch circuit feeds several outlets, and you only put a fuse on one of them, can a branch circuit feed another branch circuit?

Steve

 

[steve66]

Additionally...

You snuck that in there while I was typing but:

If I add a fuse to protect the appliance, I'm not using it as a substitute for the OCP specified in 210. I've still got a 20A breaker protecting the circuit.

And that section doesn't say the supplementary OCP can't be used for the requirements of 422.11.

 

[charlie b]

According to the definition of a branch circuit, it starts at the final overcurrent protection device.

According to that same definition, the branch circuit ends at an outlet. The definition of that word begins with, "A point on the premises wiring system. . . ." Thus, the receptacle outlet is the endpoint of the branch circuit, and the breaker in the panel is the circuit's final OCPD.

If you stick a fuse in a branch circuit, IMO, you have started a new branch circuit.

I would only agree if the fuse were within the premises wiring system. IMO, if you stick a fuse within a cord, and plug that cord into a receptacle outlet, you are outside the premises wiring system. Thus, you do not create a new branch circuit.

 

[steve66]

I would only agree if the fuse were within the premises wiring system. IMO, if you stick a fuse within a cord, and plug that cord into a receptacle outlet, you are outside the premises wiring system. Thus, you do not create a new branch circuit.

That's the way I see it too.

Steve

 

[winnie]

What would you'all say about the installation if this sort of receptacle were used:
http://www.usahardware.com/inet/shop/item/30550/icn/20-068163/bussman/bp_sru.htm

20A breaker -> 12ga circuit conductors -> 15A fuse protected receptacle -> appliance requiring 15A protection

-Jon

 

[charlie b]

My view is that anything that gets plugged into a receptacle outlet is not part of the premises wiring system. That plug-in breaker thing is a piece of utilization equipment.

 

[brother]

Thanks for the responses. just for the sake of argument, if this guy puts an inline fuse at a 'j box'(its above the ceiling) that is just before the receptacle outlet, then is the point from the j box to the out let of the receptacle the 'branch circuit'??

Just for the info I believe this would be a 'bad' practice especially if you do not identify that there is an inline fuse some where.

 

[winnie]

My view is that anything that gets plugged into a receptacle outlet is not part of the premises wiring system. That plug-in breaker thing is a piece of utilization equipment.

Agreed on things that plug in. I believe that the Bussman BP/SRU is designed to be hard wired in to a device box, providing a fuse protected receptacle. There is also a version that has a fuse and a snap switch. Does the hard wiring change the answer?

-Jon