Circuit Breakers

Post your technical questions or solutions about your boat's electrical systems or electronics here.

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nybor
Posts: 249
Joined: Sun Jan 06, 2013 7:55 am

Circuit Breakers

Post by nybor »

Sigh... Both my steaming and deck lights are out. I went up and no voltage. Next I check across the circuit breakers. In general when a breaker is off, the delta V is 12-13 volts. As soon as it is switched on, the voltage drops to zero. (seems reasonable since there is no "shut door" now that it is on. However, on the circuit breaker for the steaming light, there is no voltage across the breaker terminals when off or on.

Any suggestions on what I should check next? (switch to another breaker?) Do these normally go bad.

Also, I happened to check the fridge voltage and it is only 9.5 volts when off. Seems low. Any thoughts?

thanks
dave

ps I really want to give Ken something for all he does for us. Any suggestions? I am more than willing to contribute an Honorarium but I am not sure he would take it. (Ken if you would, please send me your mailing address!).
ElizabethG
Posts: 108
Joined: Wed Nov 02, 2016 5:43 pm

Re: Circuit Breakers

Post by ElizabethG »

Hi Dave,

I'm a little confused as to how you are testing...

I'm not at my boat, so I'm working off memory here..

One side of the DC breaker will go to a common bus bar and the other side will go to the device being powered such as your steaming light. That wire will be colored.

On my boat, that wire runs to the head. Remove the panel from under the sink and you should find a small junction box, or maybe a terminal block of some sort with the colored wire you are looking for. Check to see if you have voltage there with the breaker on. That wire then feeds up into the mast from the junction box, or terminal strip.

If you have voltage there, go up the mast to the steaming light and remove the bulb. Check the bulb socket for voltage. If voltage is there, you have a burned out bulb. (If you have the incandescent bulb, you should be able to see if the filament is burned out, or check the bulb with an ohm meter.

On my boat, the deck light and the steaming light are housed in the same fixture. The bulbs are easy to replace and I would go with an LED if they are bad.

Bill
C350 #193
Atlanta (Home) / Charleston, SC (Boat)
wolfe10
Posts: 588
Joined: Mon Dec 11, 2006 2:58 pm
Location: Ft Myers Florida

Re: Circuit Breakers

Post by wolfe10 »

nybor wrote: Mon Apr 01, 2024 10:16 am Sigh... Both my steaming and deck lights are out. I went up and no voltage. Next I check across the circuit breakers. In general when a breaker is off, the delta V is 12-13 volts. As soon as it is switched on, the voltage drops to zero. (seems reasonable since there is no "shut door" now that it is on. However, on the circuit breaker for the steaming light, there is no voltage across the breaker terminals when off or on.

thanks
dave
Agree with Bill, that is not how I would test it.

Test from good ground (voltmeter black probe) to "out" side of a breaker to test it (voltmeter red probe). Should have 0 voltage with breaker off and full battery voltage with breaker on.

Your issue could also be on the ground/negative side. Checking at the terminal strip under the bathroom sink cabinet is also where I would test. Start by verifying that the connections there are clean and tight.
Brett Wolfe
C350 #180
"Vindaloo"
Ft Myers FL
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