Help installing GFCI receptacle on "odd" circuit

Discussion in 'Electrical and Wiring' started by tft12, Jul 14, 2018.

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  1. Jul 14, 2018 #1

    tft12

    tft12

    tft12

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    I'm having a problem adding a GFCI receptacle to a circuit. I'm new to this type of work so please bear with reading the step-by-step (pictures included). I determined that the outlet I wanted to setup as GFCI was on circuit "SP#19". Circuit SP#19 has three receptacles and a few basement lights (don't confuse these lights with the circuit named "DeskLights", these are separate lights). I turned SP#19 off and then tested the hot wires of my targeted receptacle with a pen-style voltage tester. Though flipping breaker SP#19 killed all appliances on each receptacle of the circuit, the voltage tester was giving a weak but definite signal that the hot wires of my target receptacle were still hot. I went back to the panel and noticed that SP#19 is linked to the breaker called "DeskLights". I turned off the breaker "DeskLights" and rechecked the hot wires at my target receptacle on SP#19 with the voltage tester. Now I couldn't get any reading from the voltage tester, as expected. As you can see in the pictures, there is a single 3-wire (red, black, white, ground) Romex in the base of the panel with red going to SP#19 and black going to "DeskLights", so it looks like this is the reason that I get a weak signal with the voltage tester unless I turn breaker DeskLights off too.

    At my outlet, after determining which hot wire was line and which was load I turned both breakers off (DeskLights and SP#19) and then I installed the GFCI receptacle. I turned both breakers back on and then plugged in my outlet tester. No lights on the outlet tester turned on. I checked the outlet with my pen-style voltage tester and it gave a clear indication of being hot. I tried to trip the test of the GFCI but it wouldn't work. I tried resetting the GFCI but that didn't do anything. All downstream receptacles were dead according to the appliances that were plugged into them. I didn't check the downstream receptacles with a voltage tester.

    I took the GFCI out and replaced it with a standard receptacle. All of circuit SP#19 is working again (all receptacles and basement lights), but I don't have GFCI protection.

    Can anyone help me here?

    Thanks.
     

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  2. Jul 14, 2018 #2

    tft12

    tft12

    tft12

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    I've found that this type of circuit is called an MWBC and that there shouldn't be any trouble installing a GFCI receptacle on an MWBC without any modifications. Still don't know why things weren't working.
     
  3. Jul 14, 2018 #3

    tft12

    tft12

    tft12

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    Problem solved. I had the neutral load wire attached to the neutral line terminal. Oops.
     
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  4. Jul 14, 2018 #4

    afjes_2016

    afjes_2016

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    Glad you were able to solve the issue and thank you for coming back and letting us know and anyone in the future who may have the same problem. That is a common mistake people make when installing a GFCI receptacle. Now you know for the future.

    Meantime, since the circuit is a MWBC you should install a "tie bar" in the two circuit breakers making up the MWBC. This is actually by code requirements. This way both breakers will trip if one of the two encounters any issues. Tie bars are common and should be easily found online or at a big box store. Be sure you get one that is rated for your breaker panel brand and model (type of breakers). The breakers seem to be Siemans.
     
  5. Jul 14, 2018 #5

    JoeD

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    You may have trouble with the GFCI tripping if you used the LOAD terminals. On MWBC you normally don't use the LOAD terminals as desk lights part of the circuit will put current on the shared neutral and trip the GFCI.
     
  6. Jul 14, 2018 #6

    tft12

    tft12

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    Thanks a lot. I can definitely see why a tie bar should be used for MWBC (it was pretty confusing to me at first why I was still getting signal from my voltage tester after SP#19 was turned off). Unfortunately the electrician used breakers on opposite sides to create this MWBC so I don't think a tie bar can link them. In the full panel picture, the two breakers that make the MWBC is highlighted/boxed in purple and blue.

    There is one other MWBC in the panel and that one is with adjacent stacked breakers so I will definitely add a tie bar there. Thanks for the tip.
     
  7. Jul 14, 2018 #7

    nealtw

    nealtw

    nealtw

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    Can you move the breakers around so they are side be side,
     
  8. Jul 15, 2018 #8

    afjes_2016

    afjes_2016

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    Or instead of moving the breakers so they are side by side would be easier to select two same amp rated breakers that are on top of each other and exchange wires from the circuits leading to them. If a circuit wire "hot" is too short simply at a jumper wire with a wire nut.
     

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