WFCO automatic circuit breaker

[Wileykid]

Started my generator in order to run the A/C while I was working in the trailer yesterday (105* outside). Everything started and worked properly for several minutes, then the generator acted like there was a power surge for a second. I was outside, and when I went back into the trailer, no 120V. Still have 12V. I checked all the circuit breakers, and they are not tripped. For reference, I have a WFCO 8955, I believe PEC (everything is stickered up), with the T-30 transfer switch on a 2017 Stealth 2515.

This is what I found so far. When I start the generator, after the 20 second wait, I hear the "thunk" of the auto switch to provide power to the panel. Immediately after that, I hear what sounds like a circuit breaker tripping, but none of the ones I see are. I have double checked them when the generator is running, and they do not seem to be tripped. As soon as I turn the generator off, I hear the hidden(?) breaker reset. I turned the A/C breaker off to make sure the A/C was not shorting out the system somehow, but still same results. No other appliances are turned on, and the GFCI is not tripped. It was late, and I was able to do a quick check with a volt meter, and it appears the breakers I see are not getting any 120V.

The 12V side of the panel seems to be fine. No fuses blown, and everything works. Battery voltage appears fine, and is maintained on a solar float. Of course I have no charging output from the power converter to the battery.

I have been unable to find in my searches of an auto breaker between the transfer switch and the panel. But I believe there is one in the power converter. Could the power converter one be tripping and killing all 120 on the panel? If not, the transfer switch, although from what I could find, it doesn't mention an auto breaker.

The trailer is in a storage lot right now, with no way to plug in at this time.

Thanks
Mark

[ejohnson1144]

Is there a breaker in the generator compartment?

[Wileykid]

Originally Posted by ejohnson1144

Is there a breaker in the generator compartment?

Yes, and I checked it. Also, I hear the transfer switch work inside the trailer. I know I need to pull it out and check the voltage coming into the switch, I should be able to get back to the trailer tomorrow.

Mark

[ejohnson1144]

Not sure but if the transfer switch is moving then it's seeing voltage. Might want to check output wiring

[Wileykid]

That is on my next thing to do. I need to check the voltage from the generator just to make sure the regulator on it is good.

Barring the voltage regulator on the generator (ONAN 4K) going bad, my current thinking is the voltage converter went bad and the auto breaker in it is causing the panel to lose the 120?

Mark

[Bama Rambler]

I'd be more inclined to think the transfer switch is dropping out after trying to engage, or there's a loose connection inside it somewhere. The 'Reset' you hear is likely the relay dropping out after you shutdown the genny.

[Wileykid]

Great responses so far. A major thanks.

My plan of attack hopefully tomorrow will be to pull out the unit and check the generator voltage coming in. If fine, I will disconnect the output wire and see if it still disconnects, if it does, bad switch. If not, I read on the sticker of the T30 that it will not connect if voltage drops below 70%. Everything downstream is breaker protected, and I turned them off, so I guess even with that, disconnect individual stuff on the panel and see.

Mark

[Wileykid]

Well, I found the problem, as you can see in the pictures. I am going to replace the power switch (T30).

Best I can think of is the hot wire shorting out to the box, or the switch is bad. Before I took it apart, I was able to see 120 on one of the tries.

Correct me if I am wrong as to the cause. I would think the breakers before (generator), and after (breaker box) would prevent this?

Mark

[Wileykid]

Yesterday I replaced the transfer switch, and everything is working again.

Thanks again for the suggestions

Mark

[ejohnson1144]

Originally Posted by Wileykid

Yesterday I replaced the transfer switch, and everything is working again.

Thanks again for the suggestions

Mark

Wow that got hot wire nut melted and shorted

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[Wileykid]

Brainstorming with an electrician buddy, the only thing we could come up with is that all last month I was in Texas, and the A/C was running most of the time (4 weeks). The high amp draw over the time was too much for that wire connection, which could have been not connected fully or properly. The wires that melted were the output to the trailer. I was on shore power most of the time. I replaced the whole switch, as I am not sure if the switch could have contributed to the problem, and if not, what damage may have occurred anyway.

Mark

[TitanMike]

Originally Posted by Wileykid

Correct me if I am wrong as to the cause. I would think the breakers before (generator), and after (breaker box) would prevent this?

An electrical inspector explained to me one time why regular breakers don't always prevent damage like this. I was finishing a basement and doing my own electrical work. All the work passed except for the breakers that supplied the bedroom areas. Code had been changed recently to require "Arc Fault" breakers. Similar to GFCI's but they have an neutral wire connection from the breaker to monitor "high resistance shorts", As the inspector explained, you can have arcing but the actual current does not exceed the rated capacity of the breaker so it doesn't trip. The arcing causes heat (just like welding) and many fires have been caused by this.

Your replacing the entire transfer switch was a wise idea. This is also a good example of why metal enclosures are used so much with electrical devices. Keeps the "fire" contained.

Down the road you might want to pull the cover (with all electricity disconnected) and inspect the crimped/wire nut connections. Make sure they are tight and no signs of heat damage.