Cabin lights problem

[western traveler]

I have a Blue Seas fuse block. I ran separate 14ga wires +/- for each of the two disk style cabin lights. Started with 10amp fuses and went to 7.5 (Before I sealed up the roof I checked everything with a probe to confirm things were working (to my limited knowledge). Crossed negative and positive glow red correct glows green.
I added two reading lights with their own circuits as well. No problems with either of those.
When I wired the disk lights and connected to the battery they were in the switched on position and lighted up. When I hit the switch to turn off I heard the fuse blow. I confirmed I was wiring as indicated and then foolishly did this a couple more times each time burning out fuses when I using the on/off switch’s.
Thought, oh two bad lights and had Etrailer send me two more. Same problem.

This time I wired one of the lights with the fuse block hot and the light worked. When I hit the switch another blown fuse.
What am I not seeing, besides a light?

[tony.latham]

oh two bad lights and had Etrailer send me two more.

Got a link to the light? Does it have a switch or do you have an inline switch somewhere?

Tony

[twisted lines]

Your wires through the roof red is hot, black is not?

[tony.latham]

Your wires through the roof red is hot, black is not?

I think he's okay there. Running red from the positive side and black from the negative side... and connecting to the RV standard of black is positive and white is negative. Which I have always thought was as goofy as a flat earther.

Tony

[western traveler]

oh two bad lights and had Etrailer send me two more.

Got a link to the light? Does it have a switch or do you have an inline switch somewhere?

Tony

Internal switch and why I chose it.
Yep, red hot/black negative for the TD.
White wire ground and black positive on the light.
Also it is difficult to see in the photo but + and - are marked on the circuitboard.

It is blowing the fuse when I push the on/off button.

https://www.etrailer.com/RV-Lighting/Command-Electronics/328-K-1020BLSM2.html

[twisted lines]

Happens without the light, and something else on the switch?

[western traveler]

Happens without the light, and something else on the switch?

There is nothing else on that wire run but one individual light (which has a built in switch and it’s own fuse. Two identical lights with separate wire runs and separate fuses. Both behaving the same.

I disconnected the battery, replaced the fuse and wired up the new light. When I hooked up the battery the light came on each time (like they are shipped in the on position). When I press the button to turn the light off the fuse blows.
This is every time with all four identical lights. I can’t imagine them having their wires crossed.

I was diligent when I ran my wires and hooked them up to the fuse block, each 2 wire individual run throughout the TD because I have to be to avoid this type of problem where I have no clue.

[tony.latham]

Both behaving the same.

I have to believe there's something wrong with those light fixtures.

Tony

[twisted lines]

Test one on a battery with only the internal switch!

[Tom&Shelly]

Happens without the light, and something else on the switch?

There is nothing else on that wire run but one individual light (which has a built in switch and it’s own fuse. Two identical lights with separate wire runs and separate fuses. Both behaving the same.

I disconnected the battery, replaced the fuse and wired up the new light. When I hooked up the battery the light came on each time (like they are shipped in the on position). When I press the button to turn the light off the fuse blows.
This is every time with all four identical lights. I can’t imagine them having their wires crossed.

I was diligent when I ran my wires and hooked them up to the fuse block, each 2 wire individual run throughout the TD because I have to be to avoid this type of problem where I have no clue.

Are the lights grounded through the frame, or something like that?

I don't immediately see how it would matter, even if the color codes are messed up, or something, but I'm thinking it might...

Tom

[twisted lines]

I have 4 similar lights they only work one way.

[western traveler]

I ran 12ga wire from the galley to the fuse block up front through the roof and connected +/- to the battery and block.
I do not have a ground from the battery to the frame.
I did as Twisted lines suggested and yes they work if wired directly to battery bypassing a fuse. It is only when wired to those runs that they blow fuses and only when I use the on/off switch.
Yes, the on/off switch works if wired directly to the battery.
This light is working as it should as is the one on the other sude.

[twisted lines]

If you have fuses in all positions try removing them, and only use one fuse in the location you need it.
Are you familure with a meter?
I think you are going to be disconnecting some ground wires on the fuse panel to find a issue!
We have a few electrical gurues may come in, but I got paid for it

[TimC]

If you temporarily hooked up some other appliance to those wires and cycled it maybe that would tell you something. For example a fan or other small appliance.

[western traveler]

Thanks everyone for the things to check. I started with ground. Everything seems to be in order.
I am going to wire my galley light into it and see how that behaves. I have a friend coming over with a meter.

All of you are always generous with your knowledge and it is much appreciated.

The funniest thing about this is I live in the boonies. I drove to another town (ours has zip for electrical supplies) and bought all the 10amp and 7.5 the Napa Auto and Ace Hardware had. I am now down to 4 spares as each test fails it is another fuse. Not that they had so many but I have a nice little collection started.

I took a break from it until my friend comes by and sanded/fared out the fresh galley hatch fiberglass.