ECN Forum Forums Code Related Discussion NEC & other Code issues AFCI rules in the 2014 NEC

I am starting to think it is another "product" that only exists in the code. The breaker manufacturers don't seem to be pitching them on the web sites yet.

Here's a checklist by Square D
Joe Tedesco, NEC Consultant

Join Date: Mar 2012
Location: Maine
Posts: 10 Default

Received this from Leviton Engineering:--------------------------------------------------------------------------------

A listed outlet branch circuit type arc-fault circuit interrupter installed at the first outlet on the branch circuit in combination with a listed branch circuit overcurrent protective device where all of the following conditions are met: The branch circuit wiring shall be continuous from the branch circuit overcurrent device to the outlet branch circuit arc-fault circuit interrupter.
• The maximum length of the branch circuit wiring from the branch circuit overcurrent device to the first outlet shall not exceed 15.2 m (50 ft.) for a 14 AWG or 21.3 m (70 ft.) for a 12 AWG conductor.
• The first outlet box in the branch circuit shall be marked to indicate it is the first outlet of the circuit.
• The combination of the branch circuit overcurrent device and outlet branch circuit AFCI is identified as meeting the requirements for a "System Combination" type AFCI and is listed as such.


In a nutshell this means that we list the OBC AFCI Receptacle/standard breaker combination with UL. A listing will then be available that says you use Leviton’s OBC AFC receptacle to meet code requirements when using the following breakers: xxxxx, xxxxx, xxxxxxx

Trick is…right now UL has yet to issue a standard that contains testing requirements to meet this code so therefore we cannot submit for a listing. As soon as the new standard is developed we’ll proceed with the listing.



Emanuel Ramondino
Applications Engineer

T: 631-812-6705
F: 800-832-9538
eramondino@leviton.com

Leviton Manufacturing Co., Inc.
201 North Service Road
Melville, NY 11747
www.leviton.com


So, the good news is that we are not waiting on the overcurrent device manufacturers to decide to play ball...If UL would just get going on this........

on the other hand:
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http://www.joetedesco.org/JoeTedesco/Presentation1.pdf


Square D seems to have other ideas

after alot of extensive reading, it seems the whole contraversy comes down to available fault current(300a vs 500a)..The accepted fault current available for single family dwellings has widely and historically been accepted at 300A.
Now we have another study, sponsered by overdurrent device manufacturers, that claim the actual fault current available is 500A. This is the number the overcurrent manufactuers are using to sway Code making panel into demanding a listed system combination AFCI.

It seems that The UL rep did not buy that argument in the code making panel stating that once the 300a fault current is reproven for single family dwellings (worse case scenario), the rest of the data in the manufactuer's report would be faulty and the established magnetic trip ability of standard overcurrent devices with an additional ABS AFCI would be more than adequate to mitigate any arc fault problems likely to be encountered.

UL’s representative on the Code Panel voted affirmation on this action with the following comment:
“While we support the panel action, continued support is dependent upon review of additional
data that would confirm the availability of sufficient short circuit current capability at the panel of a
typical installation.
“The arc fault protection of the branch circuit will be provided by a system that includes an outlet
branch circuit AFCI, a circuit breaker having a known instantaneous trip current and a branch
circuit of a limited length and resistance to ensure that the fault current is sufficient to trip the
breaker during a parallel arcing fault at the installation point of the outlet branch circuit AFCI. The
latest UL Research Report4 takes into consideration the impact of the available current at the
panel on the acceptable length of the branch circuit home run to the first outlet. Calculation shows
that as the available current at the origin of the branch circuit varies, so does the allowable length
of the home run.
“Additional study is needed to provide data regarding the current available at the origin of the
branch circuit in a typical installation. From this data, the panel will be able to determine if
modification of the panel action should be considered at the ROC.”

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