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Bobbo's avatar
Bobbo
Explorer II
Oct 28, 2018

Really odd wiring in my TT

I am adding a 12v outlet under the table, and have a 12v circuit feeding the sub-woofer about 2' away under the same bench seat. No problem, pull the fuse and have at it. The fuse box has a fuse labeled sub-woofer.

I pull the fuse, and the sub-woofer still has power. OK, mislabeled fuse panel. I pull each and every fuse, one at a time, and the sub-woofer NEVER loses power! Huh?

I kill power to the trailer, 120v and disconnect switch, and the line is dead. I pull every fuse out, EVERY ONE, and hit the disconnect switch to turn power back on, and the wire is hot!

I have a hot 12v circuit with NO FUSES INSTALLED! NOT ONE! It is obviously after the disconnect switch, because the disconnect switch kills power to it.
  • vermilye's avatar
    vermilye
    Explorer
    Oct 29, 2018
    3X on using an incandescent test light. I've see the blown fuse indicator LEDs draw enough current that an LED fixture on the blown circuit will still glow dimly.
  • wa8yxm's avatar
    wa8yxm
    Explorer III
    Oct 29, 2018
    3 SIX FARAD.. Man that is some Hardening Cap Bank.. WOW. I have batteries that do not store that much power.

    IF that 12 volt line is a 12 volt power line to an amplified sub woofer It hould work but do put in a limiting fuse and find out what the fuse to that line is rated at. Some of those things can be 10-20 amps. your outlet should be 10. No more
  • MEXICOWANDERER's avatar
    MEXICOWANDERER
    Explorer
    Oct 29, 2018
    I had a customer on a 50' Swan sloop ask me aboard. "See this wire" he instructed "It stays hot whether the battery switch is off or on. To illustrate the point he went below and removed the master negative feed able from his Lifeline bank.

    "Now watch"

    He disconnected the 6 gauge power cable at the nav station dedicated 50 amp breaker and struck it against the side of the negative bus bar.

    Hot blue flashes. Again and again.

    "There are no other batteries on the boat" he explained. "This cannot be happening".

    Laying on my back on the teak, I slid open a floor-level cupboard. Strapped to the cubby overhead, six three-farad capacitors had been fastened. The previous owner of the boat must have been an audiophile.
  • Bobbo's avatar
    Bobbo
    Explorer II
    Oct 28, 2018
    I have the sub-woofer sitting on the top shelf of my closet in the S&B house. :) I was using an analog multimeter to check. However, now that I am thinking about it, the fuse panel has LED lights to indicate a blown fuse. I wonder if the multimeter pulled so little current that the current coming through the LED light showed up. I will have to get an actual 12v test light and try again.
  • theoldwizard1's avatar
    theoldwizard1
    Explorer II
    Oct 28, 2018
    High power amplifiers (and even some computers) will show their power indicator LED for a few minutes after the source is removed.

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