Can a GFI protect 2 separate circuits on a 12-3 cable at the same time?
Question:I have two 20 amp circuits running to an outside box on 12-3 (Red, Black, White & ground) cable. I know how to connect a GFI but not how to make a single GFI work on 2 circuits sharing a common (white). If I use 2 GFI, there is no white for 2nd GFI line-out. I connected the line-in black to load black and line-in white on GFI then line-out white to downstream recepticals. I ran red directly to a switch to control lights and a receptical. When I turned on the lamp at the switched receptical the GFI tripped immediately. When I unplug the light the circuit stays on. I checked all the connections and they were OK. The lamp wired to a cord works while plugged into the above GFI & also several others I have so I know the lamp is good. My 4 light plug tester says "hot/ground reversed" but only when the lamp is connected to the "red" circuit either hard wired directly or plugged into it's outlet. Can this be done & how or am I out of luck protecting both circuits with 1 common? Thanks!
Answers:
You cant protect two circuts with one GFI. The reason you are tripping the GFI is you are sharing a nuetral and the GFI is reading the extra load on the nuetral and a short and is tripping. You dont need a GFI for the lights. Pull yourself a 12-2 romex out to the light circut.
you can get a gfi breaker for the panel
3 wire to 2 12-2 wires to the input of 2 gfi outlets then feed through from both
the way you described can not work
2 separate GFCI circuits cannot share the same neutral (white). You can put 2 GFCI outlets on the same circuit, though. Forget about the red lead and just think black, white, and green. If you pigtail above the switch, you can have one unswitched GFI outlet and one switched GFI outlet. If you pigtail below the switch, you'll have 2 switched outlets.
No. You need a separate neutral for each circuit if the GFI is at the beginning of the circuit.
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