Electrical Question

[gman2560]

I was hanging out at the marina Sunday and our group got into a rather spirited debate about ground systems on boats. Our friend was installing a new fuse panel and common ground. The debate was whether it was "correct" for the ground to be connected directly to the negative post of the battery or whether it should be connected to the engine block.

anyone?

 

[cjames]

Re: Electrical Question

The batterys "NEG" terminal is connected to the engine block. If you connect the NEG side of any circuit to the engine block, you are essentially connecting it to the battery. The way I like to do it is to run my NEG battery cable to a lug bolted on the transom, I think its a 3/8" lug. I then run a cable of equal size to the engine block from the same 3/8" lug, and another, I think im using 4ga, to a buss bar also bolted to the transom. I ground all engine related items to the block, and all other systems to the ground buss. I also have a ground buss in the cabin for all the house systems, nav and comm stuff. (I think thats a 4ga conductor also) Its just my way of staying organized, and I can easily identify whats what and isolate a problem should it come up.

 

[Texasmark]

Re: Electrical Question

Electrical power comes from the battery. Replacement power comes from the engine's alternator. When the engine is running, both sources are generating power that other things can use.

The idea is to not have any "resistance" in the return (ground) line for your electronics because that can put noise on things you want quiet. You want them all at the same (ground) potential.

Sounds like Mr. James has a plan that solves the problem. He is insuring that the engine AND the battery ground terminals are at the same potential.

Mark

 

[wcsparky05]

Re: Electrical Question

c james, just wondering you're thinking on mounting a lug to the transon, and the engine block, on a fiberglass boat in the water, and then going to the battery is helping you at all with a dc voltage ground?

 

[Silvertip]

Re: Electrical Question

I agree. The extra ground lug just adds another point of failure and adds nothing electrically. In fact it provides a fourth ground point rather than the normal three. (Battery Neg, Engine block and console ground buss.) Not very "common" is it?