Fuse questions

[MyronL]

Got an electrical problem with my trailer. For unknown reasons the 15 amp fuse in the WFCO that governs all ceiling lights has been blowing. This is new, starting 3 weeks ago. I have not been able to track down the short that seems to be causing this. I had done some messing around with the ceiling fixtures, like adding the captains lights and a couple LED tape light strips, but nothing more serious.

Troubleshooting---I pulled out every ceiling light LED bulb, in case one might be bad, and disconnected every lighting addition I made, but that 15 amp keeps on blowing out. Trailer ceiling lights are now back to the factory config.

Have gone through at least 16 fuses doing that trouble shooting. Nothing changed. Thought the problem might be in the WFCO so, moved the red wire in the WFCO to an unused slot but the 15 amp fuse just blows out there, as well. Looked for bad grounds, etc. No joy noplace.

Today, after walking away for a few days to give myself fresh eyes for this, I went back in there and – decided this time to put a 20 amp fuse in the problem slot, instead of the standard 15 amp fuse I am used to...and see what happens.

Viola! No blown fuse, all ceiling lighting now works! What-the-Harry happened here??

[Greg and Kathy]

Not a good idea to go bigger on fuse. If you put a 15 back in and it blows there is an obvious drain. Hook up amp meter and see how much draw when all lights off. There should be very little. You should not be blowing 15 amp fuses with the Led lights.

[Greg and Kathy]

Did you put in any screws to mount anything. Possible damaged wire etc

[Iowa Dave]

Any wire strands hanging out anywhere on terminal screws
Etc?
Iowa Dave

[tdf-texas]

Originally Posted by MyronL

Got an electrical problem with my trailer. For unknown reasons the 15 amp fuse in the WFCO that governs all ceiling lights has been blowing. This is new, starting 3 weeks ago. I have not been able to track down the short that seems to be causing this. I had done some messing around with the ceiling fixtures, like adding the captains lights and a couple LED tape light strips, but nothing more serious.

Troubleshooting---I pulled out every ceiling light LED bulb, in case one might be bad, and disconnected every lighting addition I made, but that 15 amp keeps on blowing out. Trailer ceiling lights are now back to the factory config.

Have gone through at least 16 fuses doing that trouble shooting. Nothing changed. Thought the problem might be in the WFCO so, moved the red wire in the WFCO to an unused slot but the 15 amp fuse just blows out there, as well. Looked for bad grounds, etc. No joy noplace.

Today, after walking away for a few days to give myself fresh eyes for this, I went back in there and – decided this time to put a 20 amp fuse in the problem slot, instead of the standard 15 amp fuse I am used to...and see what happens.

Viola! No blown fuse, all ceiling lighting now works! What-the-Harry happened here??

If you have a multi-meter that measures DC amps, place it in series with the positive wire coming out of the fuse block for the ceiling lights and measure the amp draw on that circuit.

That will give you an idea of the total load on the circuit. Now try breaking the circuit daisy chain in the middle by disconnecting the chain at the middle ceiling light fixture and check if the load decreases significantly. If it does, the problem is in the disconnected half of the circuit. If it doesn't, the problem is in the part left connected. Keep breaking the circuit down like this until you have the fault isolated.

Something is pulling too much current - you just have to determine which device it is.

[Vermilye]

One method I sometimes use to find shorts is to replace the fuse with a 12V lamp. You may need to rig some clips, etc to do it with the blade fuses used in the converter.

In any case, when the wiring is shorted, the lamp will light, but as long as it is a low wattage bulb, not overload the circuit. Start wiggling things until the lamp goes out. That is where the short is located.

[MyronL]

Well it’s amazing, how us old guys continue to amaze ourselves. I didn’t like the 20 amp fuse solution for the blown circuit either, so I go back under the dinette table. More messing with the WFCO fuse box. I have no idea what I did that changed something but , the fuse problem is now gone.

My best recollection follows:

1. Pulled out the orange 20 amp fuse that had been in the top fuse outlet, that’s up above the blown one.
   
2. Pulled the blue 15 amp fuse below it. Pulled out the orange 20 amp fuse I had recently inserted as a replacement for the 15 amp spot for the shorted ceiling lights.
   
3. Then I shut the battery on/off switch to off. Then I went outside and unplugged the shore power line from the house.
   
4. Then I turned the trailer battery on/off switch to on, and turned the inverter on, and tested its GFI buttons.
   
5. Then I put a blue 15 amp fuse in the problem ceiling fuse spot, and in the slot above it, and put the orange 20 amp fuse back in the slot above that.
   
6. Then I got distracted and I forget what I did next. Then I noticed that the ceiling 15 amp fuse had not blown. The ceiling lights worked. I went outside and re-plugged in shore power, and, no blown fuses. Everything works.

Amazing.

[Greg A]

Loose connections in the WFCO?? Have heard several reports of this occuring, and all the jiggling around on the fuses may be behind it suddenly working.
I'd pull the panel and tighten everything just to eliminate that as the problem.

[Iowa Dave]

Originally Posted by Greg A

Loose connections in the WFCO?? Have heard several reports of this occuring, and all the jiggling around on the fuses may be behind it suddenly working.
I'd pull the panel and tighten everything just to eliminate that as the problem.

I have seen where loose connections, loose fuse sockets and wire wound around a screw the wrong way and “sticking our” have caused problems. I think Greg has a good idea here in getting right to the wire hooks up behind the panel.

When Escape trailer installed the power vent on our 19 bathroom, in a final buckle up step, a wire “got pinched” and shorted out in the panel. Nigel was reviewing the operation with us and it did not come on when the button was pushed and he declared Ta Da. He jumped on his walkie talkie and it was fixed for good in less than ten minutes. When Nigel said “Ta Da” he expected a positive result. Not political. Nigel for President
Iowa Dave

[MyronL]

Nothing loose there I can find, and believe me I looked carefully. Even removed the fuse board with printed circuits on back (pops out) thinking the short was back there but, zero sign of any disturbances or charring.

Evidently something I did in post #7 must have re-set something. But what? Maybe the inverter GFI buttons, but they did not seem clicked off to me. Regardless, all other fuses were always good to go, just the ceiling light one, which would imply the WFCO with the one exception was fine. Even scoured the batteries, looked for staples, traced wires. Seems turning the battery switch off and de-connecting shore power may be the player here. Or, Murphy's Law.