Wiring Short only under shore power

How big is the fuse and how many of what type of lights are on that circuit?

Normal battery voltage is < 12.7 (That means less than) but normal FLOAT voltage (Plugged in) is around 13.6 and charge can go to 14.6 or higher

If you have "upgraded" from 1141 to 1156 and have say 6 lamps on the circuit you went from 1.6 amps per to 2.1 that's half an amp per lamp

Or 9.6 amps at 12.8 volts (A 10 amp fuse might hold) to 12.6 (It won't but a 15 amp might)

But up it to 13.8 you add a bit more and in both cases the fuse goes POP.
Might **IF THE WIRES ARE BIG ENOUGH** just need the next size up fuse **IT THE WIRES ARE BIG ENOUGH** Double check
or go to a smaller lamp
or convert to LED's which draw "Flea power" compared to their burning hot older siblings.

Fact Most of the lamps in my apartment are LED but 3 in the bathroom were the old hot filiment type.. 120 watts of hot filiment.. Replaced with 120 watt-equivlent LED and power bill dropped about 15/month (I keep those lights on during the day) Now I think I'm 1005 LED here save for a desk lamp rarley used, a table lamp rarely used (not sure what that one is) and one florescent and 2 sewing machines.

Have you tried a different shore power source? It could be bad power coming in that shows up at the light.

I'd check and see what the charge source output voltage is. Also, make sure the charge source hasn't gotten itself in the EQUALIZE mode somehow.

And make sure your charge source is set for the type of batteries you actually have.

My Monaco and many other Monaco RV's have a bank of 120 volt fluorescent lights in the kitchen/dining area. They are on a circuit breaker however and not fuses. I would guess that the OP is talking about the halogen 12 volt lights directly over the dining table. These should normally not be affected by any shore power connection. One way to check is to take your multimeter and set it to the maximum amp setting. Remove the fuse for the lights that is blowing and check the amperage at that location by bridging your meter leads across the fuse location, with the fuse removed. Check the amps used when NOT plugged in to shore power and then check to see if it changes when shore power is applied. If it jumps up I would suspect that maybe your inverter charger output voltage is too high.

Does the fuse blow the minute you plug in to shore power? Does it matter if the light switch is on or off? Here's a couple things to think about or check.

Get some extra fuses ready.
On generator verify that the dinette light works. Turn off the dinette light and plug in shore power. Does the fuse blow?

While still plugged in to shore power turn on the dinette light. Does the fuse blow now?

Unplug shore power and turn off the dinette light.
If there is a bulb in the dinette light remove the bulb. If the light is an LED you'll probably have to take it down and possible cut one of the wires.

Plug in to shore power and see if the fuse blows.

If you have a multimeter take a voltage reading from both sides of the fuse to ground. Does the voltage jump to 120v when plugged in to shore power (it should not jump)

2012 Monaco Knight should have 12 volt lighting. Shore power would be 120 volt system. There is no direct connection between the two that could cause a fuse to blow.

Hi,

Are your dinette lights 12VDC or 120VAC? On our rig, they're operated off the 12VDC batteries.

Does your rig have a transfer switch for shore power/generator use?

On our rig, when the generator kicks in, the transfer switch connects the output of the generator to the L1, L2, neutral lines which feeds the AC breaker panel, just like the AC shore power cord does when the generator is powered down (transfer switch is off). So it's puzzling that it only happens when you're plugged into shore power. Unless you don't have a transfer switch.

On Edit: According to your profile you have a 2012 motorhome, so it should have the transfer switch. So not sure what's going on in that case. Perhaps someone who is more familiar with the electrical systems on Monaco coaches can offer some help? :)

Good Luck finding the problem.

~Rick

Check the plug end. Bet the metal tangs are loose. Assuming you have check the cable from end to end for any damage. Transfer switch also for arcing. Since it blowing a fuse, a lot easier to find.