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Old 08-30-2018, 02:31 PM   #1
mar000's Avatar
Join Date: Jul 2014
Posts: 45
Complete power loss (12 and 120 volt) and transfer switch experience

Thought I would document this problem in case it could help out others.

Went out for lunch while at a campground. Came back a few hours later to find the step cover deployed and zero power (12 or 120 volts).

Turned on the ignition switch to retract the step cover, all lights and power came back.

Turned ignition off all was gone again. Gen would not start. Turned ignition back on and started the Gen. as soon that the key was off Gen stopped.

Steps taken:
1. Tested voltage in campsite 50 amp pedestal. All was good.
2. Since I had changed the batteries a few weeks ago, started there. Tested the current on main
terminals (+&-) go 12 volts. Followed to positive from the battery bank to a black rubber cover
and discovered this.

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There was 12 volt on the bottom but not on top. So used a ratchet to see if I could loosen the bolts.
One slight turn and all power cam back. Then went off again. So I had to undo this and it took some time. Found a fuse under this that was broken.

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Spoke to Tiffin they said bypass for now but donít delay in replacing. Also said check that wires were not getting hot. They werenít.

Once this was done, I thought my work here is done. Oh but no, there is more...

3. Noticed that system was now inverting as opposed to charging and floating when plugged into shore power. Opened the load (breaker) panel and tested for power. Got 121 volts from white and black and no voltage from white and red. Checked the shore power pedestal again, all good. Followed the shore power cord into the compartment to the automatic transfer switch. Intimidating at first, but fairly basic wiring and switches that change from shore and generator power. Tested power under the shore power cord in the box all good. Tested power leaving the box to the panel no power on red.

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Asked the wife to plug and unplug the shore power a few times so I could observe what was happing. Black wire side was moving, red was stuck. Noticed black stuff on the contacts, sanded with 400 grit, fixed the problem for 5 minutes. Then I noticed that the red side of the mechanism had overheated. And eventually found that the switch was broken.

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It was 9:30 PM by then. Shut off all items consuming power except the fridge. Went to bed. Woke up to low battery alarm, and Gen wasnít going to make a difference given problem was on the power out side of the switch.

4. Then it occurred to me that I could perhaps bypass the transfer switch. In the morning I called Tiffinís electrical guy, he said yep, you can bypas, so I disconnected the shore power wire and load panel wire and connected them together with wire nuts and electrical tape, power issue resolved.

Before making the connection, I shut off the following: 12 volt coach switch, 12 volt battery bank disconnect switch, inverter power switch, 50 amp main breaker. Turned these on one at a time starting with pedestal power, checked for heat smoke, them did same at 50 amp breaker and so on.

5. Ordered a new transfer switch that I hope to have tomorrow to finish off the job.

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My theory on the transfer switch is as follows:
I. Too often we shut down the AC before re-configuring the 3 until to off in the thermostat
program, when we fire off, high demand creates an arc that weakens the switch over time. I
now plan on shutting off all major power draws before connecting to shore power or Gen.
II. We went to a camp ground with a 50 amp plug that in the end kept tripping breakers and
causing AC units to make a lot of noise. Found out later that the neighbor and I actually shared 30 amps between the two, that did a number on the switch and eventually it failed.
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Old 08-30-2018, 09:44 PM   #2
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Ray,IN's Avatar
Join Date: Aug 2001
Location: North America somewhere
Posts: 21,245
The owners manual( mine anyway) states what you found. Always turn off high-demand loads before switching power sources.
2000 Winnebago Ultimate Freedom USQ40JD, ISC 8.3 Cummins 350, Spartan MM Chassis. USA IN 1SG 11B5MX,Infantry retired;Good Sam Life member,FMCA." My fellow Americans, ask not what your country can do for you, ask what you can do for your country. John F. Kennedy
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power, switch, transfer switch

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