2011 NEC art. 210.12(B) AFCI protection for Extensions or Modifications-Dwelling Unit
- Thread starter sparky2k
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al hildenbrand
Senior Member
- Location
- Minnesota
- Occupation
- Electrical Contractor, Electrical Consultant, Electrical Engineer
We're all waiting on the manufacturer's release of the AFCI device.
Till then, we're stuck with AFCI breakers (unless there is local ordinance that gives some relief).
The GE single pole combination-type AFCI breaker (MOD 3) is really the only breaker available now that can handle existing multiwire branch circuits. Of all the AFCI combo breakers, the GE is the only one so far that doesn't have a GFI like component in it's circuitry.
A GE single pole combination-type AFCI MOD 3 breaker can be connected to one side of an existing multiwire branch circuit, by its own installation instructions.
It's either that or run all new branch circuit to refeed the outlet that is being repaired or modified.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
Some manufacturers make a DP Afci. These will work on a mwbc.
al hildenbrand
Senior Member
- Location
- Minnesota
- Occupation
- Electrical Contractor, Electrical Consultant, Electrical Engineer
Well, yes. The OP commented on that. ~$150 DP AFCI vs ~ $39 SP GE MOD3 AFCI.
The difficulty of the existing circuit holding with the SqD/CH/Siemens AFCI because of ground fault leaks and/or neutral cross circuiting, to me, is the hidden challenge. That is, the SqD/CH/Siemens double or single pole AFCIs require an absolutely correctly wired neutral and very limited ground fault bleed before they will stay on at all.
The GE MOD3 AFCI is only pure arc fault discrimination without comparing the hot and neutral currents.
When I am "modifying or repairing" an existing outlet, and am forced, by 2011 NEC 210.12(B), to add AFCI to an existing MWBC of unknown or questionable workmanship I am completely gambling on what kind of "call back" time I am in for.
To me, the simplicity of setting a small GE subpanel for its MOD3 AFCI and reliable operation (read low likelihood of call backs) is the convincing factor.
The second choice is to run a new homerun to the modified outlet.
renosteinke
Senior Member
- Location
- NE Arkansas
Yea ... installing a handle will not work. You really need to use a 2-pole breaker. $$$$$
The 2011 has a number of other new restrictions on MWBC's. It appears to me as though they're trying to ban them without directly saying so .... sort of the NFPA equivalent of the city of Gary, Ind. circumventing state laws by refusing to distribute the necessary forms to applicants (another topic, another forum).
The 2011 has a number of other new restrictions on MWBC's. It appears to me as though they're trying to ban them without directly saying so .... sort of the NFPA equivalent of the city of Gary, Ind. circumventing state laws by refusing to distribute the necessary forms to applicants (another topic, another forum).
al hildenbrand
Senior Member
- Location
- Minnesota
- Occupation
- Electrical Contractor, Electrical Consultant, Electrical Engineer
210.4(B) only requires a "simultaneous disconnect", not a "common trip".
Take a look at this GE document. Note at the end of the paragraph that GE tells you to use a handle tie on their CAFCI single pole when used on a multiwire branch circuit (MWBC).
Think about it. This permits me to put a GE MOD 3 CAFCI on one side of a MWBC beside a plain old single pole breaker and use a handle tie. That's a huge advantage. Just try it with a Square D, Siemens or CH single pole . . . they'll never hold because of the ground fault detecting portion of the AFCI circuitry. But the GE MOD 3 has no ground fault detection. It is pure AFCI.
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