AFCI-branch circuit design

[Pat Beaird]

How do you install a branch circuit that requires an AFCI breaker? Why does the code require that the branch circuit wires be installed in conduit between the breaker panel and the first outlet?

 

[Sierrasparky]

Welcome to the forum! :thumbsup:

I am not totaly sure of your question.
AFCI circuits do not have to be in conduit, That is an exception until the first outlet.

By the way what kind of work do you do?

 

[mjf]

Welcome to the forum! :thumbsup:

I am not totaly sure of your question.
AFCI circuits do not have to be in conduit, That is an exception until the first outlet.

By the way what kind of work do you do?

What is this exception? (Is it from the 2014 NEC?....I'm still under the 2008)

 

[Sierrasparky]

What is this exception? (Is it from the 2014 NEC?....I'm still under the 2008)

From 2008


Exception No.1 Where RMC, IMC, or steel amored cable, Type AC, Meeting the requirements of 250.118 using the branch circuit between the branch-circuit overcurrent device and the first outlet, it shall be permitted to install a combination AFCI at the first outlet to provide protection for the remaing portion of the branch circuit.

 

[Sierrasparky]

You do not need to install the AFCI in a metallic raceway or cable. The code allows for the exception and I believe this to be because in a non-metallic un-protected cable a ARC fault can cause the conductors to heat up and cause a fire. If contained in a metallic raceway this cannot happen. If the firs and subsequent outlets are protected then you have a realatively safe system.

Others correct me if I am wrong.

Since you had not installed these before you should read up. There are a lot of pro's and con's.

Many pull their hair out diagnosing a AFCI trip. I hat the time consumed also. However I usually find the problem and the customer is glad to have the wire with the nail through replaced or the loose connection at a outlet almost causing a fire.

good luck in your Journey!

 

[charlie b]

The basic requirement of 210.12 is that for the specific rooms listed in the article, you must provide AFCI protection for the entire circuit. If you use an AFCI circuit breaker, you clearly will be protecting the entire circuit. But if you instead want to use a normal circuit breaker, and if you want to install an AFCI device at an outlet box some distance from the branch circuit panel, then the portion of the circuit between the breaker and the outlet box will not be protected by the AFCI device. That is, in this type of installation you are not protecting the ENTIRE circuit. But there is an exception that allows this type of installation. The exception says that the AFCI device must be installed at the very first outlet box in the circuit. It also says that you must use one of the conduit types that have already been mentioned. The idea here is that there is a very low risk that an arc fault would take place within the conduit, since the conduit will be protecting the wires from physical damage.

 

[Sierrasparky]

Charlie ,
Much better stated!

 

[mjf]

From 2008


Exception No.1 Where RMC, IMC, or steel amored cable, Type AC, Meeting the requirements of 250.118 using the branch circuit between the branch-circuit overcurrent device and the first outlet, it shall be permitted to install a combination AFCI at the first outlet to provide protection for the remaing portion of the branch circuit.

Thanks. Good info to be aware of. Don't see myself taking advantage of the exception though. Mostly use NM.

 

[Pat Beaird]

AFCI-branch circuit design in NEC

AFCI-branch circuit design in NEC

The basic requirement of 210.12 is that for the specific rooms listed in the article, you must provide AFCI protection for the entire circuit. If you use an AFCI circuit breaker, you clearly will be protecting the entire circuit. But if you instead want to use a normal circuit breaker, and if you want to install an AFCI device at an outlet box some distance from the branch circuit panel, then the portion of the circuit between the breaker and the outlet box will not be protected by the AFCI device. That is, in this type of installation you are not protecting the ENTIRE circuit. But there is an exception that allows this type of installation. The exception says that the AFCI device must be installed at the very first outlet box in the circuit. It also says that you must use one of the conduit types that have already been mentioned. The idea here is that there is a very low risk that an arc fault would take place within the conduit, since the conduit will be protecting the wires from physical damage.

thanks for the clarification. Pat Beaird

 

[Pat Beaird]

AFCI-branch circuit design in NEC

AFCI-branch circuit design in NEC

I think this exception will come more into play when Combination AFCI receptacles are used more. For example: If you wanted a branch circuit which is AFCI protected and you didn't want to go all the way down to the basement or out to the garage to reset it this arrangement would be beneficial. It is the same secenario as when GFCI receptacles and breakers came into use. The only problem is that the run between the SE panel and the first outlet could be more cost up front.

 

[mike1061]

You could also run into this when you use a multi wire branch circuit. You could use one of the combo receptacles, to protect only the bed room. While the rest of the wires serve other parts of the house. If you meat the other requirments.
Thanks
Mike