I am renovating part of my house, and taking the time to update some old wiring that is now exposed. The old wiring is primarily #14/2c WITH NO BARE BONDING CONDUCTOR. This means that no device boxes are bonded to earth ground, and neither are the receptacles on those circuits.
I have run a new feed from a circuit breaker to a device box which now contains a UL/CSA approved Leviton AFCI/GFCI receptacle. This box is now bonded to earth ground. From this first device on the circuit, I ran a new cable, 14/2 with bare bonding conductor, to another device box for light switches (now bonded), with feed through to another device box with switches and junctions to old wiring. This last box has older wiring that feeds lights and receptacles that have no equipment bonding conductor. Are these last devices protected by the upstream AFCI/GFCI device (the ones with no equipment bonding)?? My understanding of this AFCI/GFCI device is that it detects differential current between the hot and neutral. If there is no equipment bonding to earth, and if a fault exits, where does that current go, and how would the AFCI/GFCI device function?
Best Answer
Yes, GFCI decices don't require a ground to function, they don't even use ground.
If current is following a third path, causing a trip, then who knows what the third path is? We just know it shouldn't be there. The assumption is that an unwitting human is the third path. Maybe they're touching the equipment while leaning on a water pipe.
AFCI is a totally different thing than GFCI. GFCI protects humans from shock, AFCI protects the building from fires due to arcing wires in the walls. It does that by listening for the "hooking up your speakers with the power on" sound. AFCI works best in the panel; it defeats the purpose to put it past the wires it's there to protect.