Generac 6852 Transfer Switch installed (to power my house from the Pro Power 240V plug)

[Henry Ford]

Another possibility is that a hot from each panel are connected together.

This makes more sense than hot touching ground. Hot touching ground would cause a breaker to trip.

Sponsored

 

[Lightning Rod]

After almost 2 years of it being installed, I finally am using my Lightning to power my home! The lights went out at 11:40 am EST and they are still out 2 hours and 10 minutes later. I'm going to use my wife's car to go to work soon.

With the transfer switch, will the green Utility light light up when the power comes back on? I told her to go and look at the transfer switch every 30 minutes or so and if the green light is on, she can throw the switch back towards the green light, and the house will be on regular power again. Did I advise her correctly?

Thanks.

I just realized that I left the heated seat running the whole 2.6 hours.

 

[BhamDCam]

@Maquis @Henry Ford

I finally got a chance to troubleshoot this and found the circuit on the main panel (MP) and the transfer switch (TS) that was causing the fault. These two breakers share the same 3-conduit wiring (two hots, one neutral, and one ground) - the hot on the MP breaker powers the dishwasher; the hot on the TS breaker powers the circuit the refrigerator is on.

I do know that the refrigerator circuit has some bootleg grounds on some of the outlets. They were that way when we bought the house six years ago (built in 1950).

My two main questions are:
- Does the dishwasher also need to be on the TS? Is the wiring being "split" between the refrigerator and dishwasher possibly causing it to fault? I doubt it, but I could be wrong.
- Or is it just the bootleg grounds causing the issue? I know that if nothing is plugged into these outlets then PPOB won't fault.

At the very least, I know the two circuits causing the issue and when I get more time I can continue troubleshooting.

 

[Henry Ford]

All neutrals in the switch panel need to only be in the switch panel. If the circuit in the main panel is returning on the neutral in the switch panel the trucks GFCI will detect the amperage difference and trip.

I'm not sure how to fix your issue at the moment. Others might have an idea.

 

[Maquis]

@Maquis @Henry Ford

I finally got a chance to troubleshoot this and found the circuit on the main panel (MP) and the transfer switch (TS) that was causing the fault. These two breakers share the same 3-conduit wiring (two hots, one neutral, and one ground) - the hot on the MP breaker powers the dishwasher; the hot on the TS breaker powers the circuit the refrigerator is on.

I do know that the refrigerator circuit has some bootleg grounds on some of the outlets. They were that way when we bought the house six years ago (built in 1950).

My two main questions are:
- Does the dishwasher also need to be on the TS? Is the wiring being "split" between the refrigerator and dishwasher possibly causing it to fault? I doubt it, but I could be wrong.
- Or is it just the bootleg grounds causing the issue? I know that if nothing is plugged into these outlets then PPOB won't fault.

At the very least, I know the two circuits causing the issue and when I get more time I can continue troubleshooting.

What you are describing is called a multi wire branch circuit (MWBC). 2 hots share 1 neutral. It’s critical that both circuits originate from the same panel. This is definitely causing your problem. Bootleg grounds are irrelevant as far as this issue is concerned.
The easiest solution is probably to move the dishwasher hot to the transfer switch panel (if you do, see the cautions below). Another option would be to run an entirely new circuit to the fridge and return the old fridge circuit to the main panel.

There are some important things to consider regarding MWBCs. The hots must be on opposite legs,otherwise you will overload the neutral.
Starting with either the 2008 or 2011 NEC, a MWBC must either originate from a 2 pole breaker, or adjacent breakers with handle ties. The intent is to be sure both hots are deenergized when you switch one off.

 

[BhamDCam]

@Maquis okay, I think I understand.

In the pic of my MP below, the circled breakers are the for the MWBC that the refrigerator and dishwasher are on. The breaker that is ON is for the dishwasher; the breaker that is OFF is currently unused since the refrigerator is now running through the transfer switch.

If I understood you correctly, I could replace the single breaker in the transfer switch with these two smaller ones, and add the dishwasher to the transfer switch. I would just need to add a handle tie so that they’re both on or off at the same time.

Should that fix the issue and be the correct way to do it?

 

[MBM]

@Maquis okay, I think I understand.

In the pic of my MP below, the circled breakers are the for the MWBC that the refrigerator and dishwasher are on. The breaker that is ON is for the dishwasher; the breaker that is OFF is currently unused since the refrigerator is now running through the transfer switch.

If I understood you correctly, I could replace the single breaker in the transfer switch with these two smaller ones, and add the dishwasher to the transfer switch. I would just need to add a handle tie so that they’re both on or off at the same time.

Should that fix the issue and be the correct way to do it?

yes, you were on the right track with moving those breakers into the transfer panel. However, since you have a multiwire branch circuit, you cannot properly feed that from the Breaker you have in the photo. You will need to use two full spaces in the transfer panel, as mentioned before, or you can also look up quad breaker. It will need to look like what I have circled in the photo.

as you are aware, I’m sure, the purpose of the transfer switch is to provide isolation between the two power sources, in this case PPOB and the utility power. From what I understand, yours has a connection from one power source to the other through the sharing of the neutral. Probably something that could have or should have been identified by your electrician during the installation.

 

[Maquis]

@Maquis okay, I think I understand.

In the pic of my MP below, the circled breakers are the for the MWBC that the refrigerator and dishwasher are on. The breaker that is ON is for the dishwasher; the breaker that is OFF is currently unused since the refrigerator is now running through the transfer switch.

If I understood you correctly, I could replace the single breaker in the transfer switch with these two smaller ones, and add the dishwasher to the transfer switch. I would just need to add a handle tie so that they’re both on or off at the same time.

Should that fix the issue and be the correct way to do it?

If that GE panel works the way I think it does (I haven’t seen one in years), those slim breakers are both powered from the same leg, which means they can’t be used for a MWBC. Please verify.
When you move it, make sure that the neutral for the MWBC also lands in the transfer switch panel, and that each hot is powered by a different leg.

 

[chl]

I think you have a ground fault caused by the MWBC, as suggested by Maquis above in #200 post.

The ground fault occurs because one circuit of the MWBC is not being switched by the transfer switch so a return path exists because of the shared neutral into the main panel.

When the main panel breaker is on, then one leg of the panel which feeds the circuit NOT moved to the transfer switch is electrically connected to the neutral through the supply transformer as can be seen in the diagram below..

In essence the result is you have a circuit neutral that is bonded and grounded in two places which will be detected as a ground fault by the Lightning.

I believe one solution is to put/move both of the circuits of the MWBC in the transfer switch OR isolate them onto separate breakers and separate neutrals, one in the transfer switch and one not.

Probably in either case, the best thing to do would be to separate them with their own individual wiring and breakers, not sharing a single neutral wire, that's what I'd do anyway.

I think your electrician might have/should have realized this was going to be an issue if he had done a thorough inspection of your wiring.

I am an electrical engineer NOT a licensed electrician although I have some experience with residential wiring.
----
Disclaimer

The information provided in this post is provided for information purposes only and does not constitute any endorsement or recommendation. No warranty, expressed or implied, is made regarding the accuracy, adequacy, completeness, legality, reliability, or usefulness of any information found in this post. It is your responsibility to verify and investigate this information.

Sponsored