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Re: Masse negative leak

Sv Garulfo
 

Nick,

Remember that there may be more than one source for the leak. In that unfortunate case, you would not find the leak by disconnecting a faulty circuit since another faulty circuit will still show the leak in the tester. 
The laborious but absolute process is to disconnect all but one circuit to validate that circuit is ok. Until you find one that is faulty. Fix the issue and move to the next one. Until you’ve done them all. It can be a lot of work. 
It makes sense to start from the battery bank (the tree root) and find the faulty branch(es) up to the faulty equipment(s). 

To make things easier, you can build a portable tester with an Led bulb and 2 wires long enough to connect to the bonding system (closest available spot to the connection you are working on, could be the rigging/rail depending on your 54 hull number) and the battery positive (when searching for a negative leak). That battery positive would be very close to where you’re working since you’re only disconnecting negative cables. That way you can test directly the existence of the leak. 
The led bulb will also be more sensitive to the strength of the leak than the built in tester. 

When we went through that exercise on Garulfo, we found 2 leaks in the forward locker: navigation lights; the negative wire was chafed and allowed a connection to the handrail tube it went through, and bow thruster; probably some carbon dust as the leak was weak and intermittent. 

Hope that will help, 

Good luck,

Thomas
GARULFO 
A54-122
Tahiti 



On Fri, 24 Jul 2020 at 08:02, Craig & Katherine Briggs SN 68 Sangaris Tropic Isle Harbor, FL via groups.io <sv_sangaris=yahoo.com@groups.io> wrote:
Hi Nick,
Bill's comment that these problems can be elusive and your saying it is a straight run in a conduit reminded me of a problem in SM Miss Lindy years ago. They had had near-fire meltdowns of all the major wires in the engine room (looked like Dali's clocks dripping). Three times over just a few months!

Each time they had "professional marine electricians" replace all the damaged wires. After rewire #3 in Cartagena, we happened to be leaving the same day and they had meltdown #4. We got them to anchor near us in the San Blas and I spent 3 days cobbling their system back together. I finished, but noticed a slight potential between the start negative and the engine block. Scratching my head and thinking I was wasting my time, I disconnected the battery wires and pulled them out of the conduit a few feet. Sure enough, there was a slight chafe-through in the insulation that under the right conditions underway would allow a dead short.

Obviously just a shot in the dark and unlikely to be the cause, but maybe worth pulling and inspecting the wires in the conduit.

Good luck with it,
Craig

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