Home transfer switch

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skater
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Home transfer switch

Post by skater »

Well, I finally got the transfer switch wired into my house's wiring, the idea being that if there's a power outage I can plug in the camper's generator to run certain circuits (furnace fan, fridge, some lights; not all at once).

Problem is... it's not working! And the reason is that I don't have a separate ground in my house's wiring; the neutral and the ground are one and the same, so the GFCI breaker in the camper trips as soon as I plug it in. I think.

D'oh!
1991 Airstream B190 - bought, 2005; sold, 2011; bought 2017
1995 Airstream Excella 30' trailer

WBCCI #13270, Washington, DC Unit
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bryanl
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Post by bryanl »

the GFI in the rig shouldn't be causing any grief. If you reset it, does it immediately pop off again? If so, you need to start isolating segments to find out what is tripping it.

The neutral and ground should be bonded together and to the house main ground. This should happen at the transfer switch or house service entrance.

also note that the transfer switch in the B-Van takes a few seconds to activate to allow the genset to stabilize. I haven't checked, but I don't think the van transfer switch bonds neutral and ground. Neither that bonding nor earth grounding is code required for a portable genset like in the van.

check your wiring very very carefully. You have selected circuits or parts of circuits that are being isolated from their primary circuit breaker so they need to be out on a separate sub panel and that has some interesting requirements, too.

Make sure the house transfer switch is working without any loads attached first. If that doesn't work, disconnect it and make sure the genset feed to the transfer switch comes up and stays up. - ye old isolate and verify routine is a pain but is usually works.
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skater
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Post by skater »

The GFCI is tripping immediately as soon as I reset it.

I plugged in a radio at the end of the extension cord, reset the GFCI, and it worked fine. Unplugged the radio, plugged back into the transfer switch, and the GFCI tripped - even without any of the switches set to "Generator".

Everything is working correctly when the switches are set to "line".

I checked for shorts as I installed everything, and made sure that the switches were working as designed - i.e., when it was set to off, there wasn't any continuity from the output wire to either the plug or the wire from the breaker, when it was set to "generator" there was only continuity between the plug and the output, and so on. Everything checked out fine, but I'll check it again. Since I think it was tripping the breaker even when the switches were off, it shouldn't be hard to track down a short somewhere (i.e., it has to be in the transfer switch itself).

Also, one other thing - I have a flaky GFCI outlet in my house that has caused problems before (one day I was sitting there eating dinner, and it tripped, shutting off some of the lights). This flaky GFCI outlet is actually on the back of the house, outside, but then some of the wiring inside the house is electrically downstream of the GFCI outlet. I didn't even think about it until it started acting up the day after I did the transfer switch installation, but after I popped it out of the box and put it back in, it has been fine. (I'm thinking it's one of three things: 1. The GFCI outlet is going bad, 2. There's an intermittent short somewhere, or 3. Moisture sometimes gets into the GFCI outlet and causes it to trip - we had a lot of rain last week.) I'll "trip" this outlet during my next round of testing with the camper's generator and see if it makes a difference. I've been meaning to replace both it and another GFCI that failed testing when I bought the house.

Thanks for the advice!
1991 Airstream B190 - bought, 2005; sold, 2011; bought 2017
1995 Airstream Excella 30' trailer

WBCCI #13270, Washington, DC Unit
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skater
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Post by skater »

Okay, there appears to be no short that I can find.

There was continuity, but that's not surprising considering there was a load on the circuits I was testing. When I unplugged everything, the continuity went away. Good sign.

Unfortunately I wasn't able to test it because the generator wouldn't start. Perhaps I just had too much load on the circuit when I tried the generator. That shouldn't be the issue (aren't GFCIs usually good for 20 amps downstream?) but it's the only thing I can figure. I was going to test it on the circuit that I unplugged everything and go from there.
1991 Airstream B190 - bought, 2005; sold, 2011; bought 2017
1995 Airstream Excella 30' trailer

WBCCI #13270, Washington, DC Unit
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bryanl
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Post by bryanl »

at least its consistent -

now you can isolate things down to one item at a time to find out what it is that is tripping the GFI - once you get then genset going again.

The GFI is supposed to trip only when there is a mismatch between currents between the hot and neutral of only a few milliamps. That mismatch can occur in several ways.

1) an overload condition might trip it in addition to a mismatch.

2) there is a 'ground fault' allowing current to leak out of the hot to neutral circuit to ground.

3) the GFI device is malfunctioning

4) there are impedance effects interfering with the GFI operation.

5) other things (always have to have an etc in a list like this!)

Good luck, have fun. It can be rather tedious tracking down what is tripping the GFI but at least it is consistent and not intermittent.
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bryanl
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Post by bryanl »

Also, one other thing - I have a flaky GFCI outlet in my house
only one is needed to protect an entire circuit. code requires that all outside circuits and any near faucets or other potential earth ground needs GFI protection.

Being that the GFI device is so sensitive and quick acting it can fail. That is why they have the test button on them. (no, not to test, dummy ;-), but to tell you that failure is such a risk that having a test is necessary!)

A GFI outlet isn't usually that expensive so replacing a flaky one is usually good preventive maintenance. Just hope you don't get a defective outlet as a replacement (been there done that)
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skater
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Post by skater »

Okay, got the generator running again today. It runs much better when it's close to level (side to side).

After running it a couple hours as part of regular maintenance, I tried the transfer switch again. The camper's GFCI tripped as soon as I plugged the cord in; I didn't even have any of the switches set to the "generator" position.

I think the GFCI in the camper just doesn't like the shared ground/neutral thing. I've checked the wiring in the transfer switch itself; there's nothing wrong and it's wired exactly as it should be.
1991 Airstream B190 - bought, 2005; sold, 2011; bought 2017
1995 Airstream Excella 30' trailer

WBCCI #13270, Washington, DC Unit
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skater
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Post by skater »

Update on this: I still haven't gotten it working, and I'm still having the same problem - that is, as soon as I plug in the cord, it trips the GFCI breaker even if none of the house switches are set to the generator position.

Here's what I've checked:
1. The transfer switch is wired correctly. That is, the hot terminal in the plug (where the generator plugs in) is the one it should be, as verified by the other outlets in the house, and the neutral and ground have no voltage between them. Further, the hot wire is not shorted to either neutral or ground.

2. The RV is also wired correctly - that is, the hot terminal is hot and the neutral and ground terminals are not. I also verified that the wiring on the outside plug matches the internal GFCI just to eliminate that as a possibility. Also the ground and neutral on the camper appear to be bonded (I will double check this), just like in the house.

So, both the camper and the house are wired identically as far as I can tell. There aren't any shorts that I can find.

The only thing left that I can think of is as bryanl suggested the GFCI outlet is bad.
1991 Airstream B190 - bought, 2005; sold, 2011; bought 2017
1995 Airstream Excella 30' trailer

WBCCI #13270, Washington, DC Unit
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Waliegater
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Re: Home transfer switch

Post by Waliegater »

skater wrote:Well, I finally got the transfer switch wired into my house's wiring, the idea being that if there's a power outage I can plug in the camper's generator to run certain circuits (furnace fan, fridge, some lights; not all at once).

Problem is... it's not working! And the reason is that I don't have a separate ground in my house's wiring; the neutral and the ground are one and the same, so the GFCI breaker in the camper trips as soon as I plug it in. I think.

D'oh!
Hi Skater,
I know this is an old post but Ill answer anyway for anyone else. The neutral and ground wire are connected at the generator ( I believe internal) . In your house panel, the neutral and ground are connected together. If you transfer switch does not switch the neutral (separating it from the house) your GFCI receptical will see this as a fault because current can travel back to the
GFCI through the ground.
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skater
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Re: Home transfer switch

Post by skater »

Waliegater wrote: Hi Skater,
I know this is an old post but Ill answer anyway for anyone else. The neutral and ground wire are connected at the generator ( I believe internal) . In your house panel, the neutral and ground are connected together. If you transfer switch does not switch the neutral (separating it from the house) your GFCI receptical will see this as a fault because current can travel back to the
GFCI through the ground.
Thanks. I finally got around it by plugging it into where the converter was plugged in (not GFCI).
1991 Airstream B190 - bought, 2005; sold, 2011; bought 2017
1995 Airstream Excella 30' trailer

WBCCI #13270, Washington, DC Unit
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