GFCI use

| Conditions: A 3 wire run from a breaker box, with alternate phases used to | feed two circuits. So, - two 20A circuits run on a 3 wire #12 cable. | | Question: Can a GFCI breaker be used effectively? The common white wire is | handling the ground for both circuits (R/W and B/W). At this stage GFCI | outlet(s) is planed, but changing a breaker would be easier and more | encompasing.

A 2-pole breaker would do it. The disadvantage is both circuits go off if either has a reason to trip the breaker.

A pair of 1-pole breakers will not work. The reason is there is no way to consistently measure the neutral current to see if it is in balance with the hot current unless measuring both hot curents together, which is what the 2-pole breaker does.

Thanks Phil. Thats what I suspected and why the original intent to use individual GFCI duplexes. These are generally for kitchen circuits and I don't care to use a common trip device.

This works with 2 GFCI receptacles and a regular

- |2| LINE LOAD |P|-Hot -----------------+ +------+-------}}-- |O| | | | |L| [GFCI] [Recpt.] |E| | | | | | | +------+-------}}-- |B| Neutral -------------+ |R| | +------+-------}}-- |E| | | | |A| [GFCI] [Recpt.] |K| | | | |E|-Hot -----------------+ +------+-------}}-- |R| -

You cannot use a GFCI breaker in a multiwire branch. Ed

Thanks "ehsjr". That is the coures chosen. GFCI duplex after the "split" to a two wire circuit at the first outlet. Same on the other 2wire leg.

Rack

You can split off a 2 wire circuit anywhere on the multiwire branch - doesn't have to be the first outlet. I mention that, because while you may already know that, others may not.

Ed

On Wed, 24 Jan 2007 02:41:00 GMT ehsjr wrote: | Rack wrote: |> Conditions: A 3 wire run from a breaker box, with alternate phases used to |> feed two circuits. So, - two 20A circuits run on a 3 wire #12 cable. |> |> Question: Can a GFCI breaker be used effectively? The common white wire is |> handling the ground for both circuits (R/W and B/W). At this stage GFCI |> outlet(s) is planed, but changing a breaker would be easier and more |> encompasing. |> |> | | This works with 2 GFCI receptacles and a regular | 2 pole breaker: | | - | |2| LINE LOAD | |P|-Hot -----------------+ +------+-------}}-- | |O| | | | | |L| [GFCI] [Recpt.] | |E| | | | | | | | +------+-------}}-- | |B| Neutral -------------+ | |R| | +------+-------}}-- | |E| | | | | |A| [GFCI] [Recpt.] | |K| | | | | |E|-Hot -----------------+ +------+-------}}-- | |R| | - | You cannot use a GFCI breaker in a multiwire branch.

Unless it is a 2-pole breaker with the neutral passing through (some larger current 2-pole GFCI breakers don't provide a neutral terminal, such as the 60-amp one from Square-D). But the OP apparently wants to minimize common trips, so your example above is what he needs if he can do the two separate branches of 2-wire wiring following the GFCI receptacles.