Isolation in ground circuit?

[BobT]

Electrical guys please enlighten. This little gizmo was between the ground wire and the negative buss as part of the old windlass circuit. The whole system was undersized and ancient, but what purpose would this have served?

Thanks

 

[kloudie1]

Looks like a pair of paralleled 40 ampere circuit breakers that would theoretically trip at 80 amperes.. Interesting location in the circuit.

 

[IStream]

Agreed, let's hope that installer never worked on AC circuits.

 

[BobT]

One time breakers or fuse-able links? There's no visible means to reset them. To the installer's credit, there was a master breaker with a pilot light on the front end of the circuit as well. It was even within a reasonable distance of the battery switch. 6ga wire and an old planetary gear unit though. No real surprise the thing wouldn't pull the hat off your head. Thanks to Maine for the crimper recommendation. And SBO store for the matching lugs and cable. This upgrade is a biggie.

 

[woodster]

those breakers look like the resetting kind that when they cool down reset on there own

 

[uncledom]

I think they stuck it in en leu of a thermal overload. Just a guess.

 

[hawntiki]

If that was the only place where the shore side ac ground connected with the negitive for for the dc circuits, might want to make sure they aren't diodes back to back.

 

[BobT]

It was on the DC negative buss in the breaker panel. That buss is separated from the AC neutral buss, but everything gets grounded to the engine block eventually. The new circuit will skip the breaker panel entirely and ground to a big negative buss bar with the batteries.

 

[uncledom]

Kloudie1 is right they are two 40 amp circuit breakers in parallel giving 80 amps of pass current. I would bet my pay check on it. In DC circuits the current flows from negative to positive so some people build circuits with the protection closest to the negative terminal. Because you need both positive and negative to complete the circuit and one without the other is useless, and because in automobiles we make the negative the chassis common, we fuse the positive. The English used to build quite a few cars with positive chassis. I'm still thinking they used it as a make shift thermal overload because it resets automatically over time.

 

[BobT]

Yes! English positive grounds! I remember the '68 Ford Cortina I drove occasionally. (Because it was such an unreliable old hulk.) I paid almost nothing for the car and way too much for the re-wire job after a battery fire. Hmmm.