Okay we don’t all scream, but many do. The 2014 NEC is moving one step closer to the eventual goal of whole house AFCI (Arc Fault Circuit Interrupter) protection. As a home inspector in Washington State we are required to report the location of any inoperative or missing GFCI and/or AFCI devices when they are recommended by industry standards. So keeping up on these new rules is very important.

In review some of the new requirements I had some questions on AFCI protection.  The code provides 6 ways to provide this AFCI protection. In one of the provision options for AFCI branch circuit protection you are allowed to install a listed outlet branch circuit (OBC) type AFCI at the first outlet on the circuit.

(OBC type AFCI)

So my thought is if we are moving toward whole house protection what about the wiring from the panel breaker to this device?

Well here is where it gets interesting. It turns out that the outlet branch circuit (OBC) type AFCI will provide both upstream and downstream protection from series arc faults.

But what about the more dangerous parallel arcs? The OCB type AFCI will only provide downstream protection.

Turns out that from studies that wiring from the panel to the OCB AFCI (Home run) a regular circuit breaker usually clears a parallel arc fault for that portion of circuit. This is based on the current being high enough to trigger the trip value of the circuit breaker and due to the fact there is a low impedance path between the breaker and the OCB AFCI device.

The impedance is dependent on the circuit length and that is why you only allowed to use the outlet branch circuit (OBC) type AFCI where the home run length is 70 ft or less for 12 AWG and

50 ft or less for 14 AWG.

So as we move to the new standards we as Home Inspectors will be seeing these devices showing up more and more.

“If you think it's expensive to hire a professional to do the job, wait until you hire an amateur.”

Red Adair

NCW Home Inspections, LLC  is a Licensed Washington State Home Inspection service located in Wenatchee Washington serving Chelan County, Douglas County, Kittitas County, Okanogan County and Grant County Washington and the cities of Wenatchee, Leavenworth, Cashmere, Oroville, Cle Elum, East Wenatchee, Quincy and many more…  

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