Arc Fault False Tripping

[TheReverend]

I understand that if you try to share a neutral with an arc fault breaker you will get false tripping.

Are there any other known situations that can cause false tripping? How about a GFI plug in the washroom connected to the master bedroom protected by an AF breaker?

[suemarkp]

What causes the problem is the same in an AFCI or a GFCI, as they both have the same mechanism to detect leakage (the thrreshold is just higher in an AFCI).

If you have a true multiwire branch circuit (two hots using a common neutral, like the classic Canadian kitchen receptacles), then you can't use two single pole AFCI or GFCI breakers as they will trip. A double pole AFCI or GFCI breaker would work fine. A GFCI receptacle will trip if the downstream (load side) receptacles get their power from the leg that is different than the LINE leg serving the GFCI. Splitting a GFCI circuit so that leg 1 gets a GFCI receptacle and leg 2 gets a separage GFCI receptacle will work just fine. Just keep all the leg1 receptacles connected only to leg1 (so 12-2 cable would be all that is required downstream of the GFCI).

AFCI's only come in breaker form, so if you have a multwire branch circuit, you must have a two pole AFCI. These are rather rare and quite expensive if you happen to find one for your panel.

[TheReverend]

Now what would happen if you were to put a GFI socket on an AFCI protected circuit? Such as running a bathroom shaver off of the bedroom circuit in a master bedroom/bath situation? Just make sure that the GFI socket is physically the last item on the line?

[suemarkp]

Its not a problem, and you can even daisy chain GFCI's if you want to. Daisy chaining GFCI's is bad practice, because you never know which one will trip first. The AFCI has a higher trip threshold, so the GFCI will trip first on a small fault (assuming the fault is downstream of the GFCI).

[scuba_dave]

My AFCI circuit does not like 2 old lamps & a surge protector I have
There are also certain vacuum cleaners that will trip AFCI