Where to Ground to??

elvisnpriscilla · #1 (**permalink**) 02-23-2003

Hi all...I juust purchased a 1970 cal25 and am in the process of gutting the electrical and re-wiring. My question is: to what do I run the MAIN ground to? I am told that a main ground needs to be attached to the hull somwhere at the keel.
Any suggestions???

DuaneIsing · #2 (**permalink**) 02-24-2003

elvisnpriscilla,

With all due respect, if you are taking on the task of complete rewiring, you need to purchase an up-to-date reference book which describes all the things you should be doing, and not doing. I''m sorry I don''t have any to recommend, but my understanding is that even a competent land electrician has a lot to learn about marine electrical wiring.

If my fellow SailNetters agree, perhaps someone can recommend a good reference book for you.

Good luck.

Duane

fourknots · #3 (**permalink**) 02-24-2003

First, get Calder''s Boatowner''s Mechanical and Electrical Manual.

If you have an inboard, all grounds go to the engine block. You don''t need to attach the ground to the keel. If you want to bond the system, you''ll run grounds to all thru-hulls, but it''s not necessary on a boat like yours and I wouldn''t do it.

If you have an outboard, I suspect you''ll need a ground bus for all grounds.

jklewissf · #4 (**permalink**) 02-24-2003

Calder''s book is the one to get. I have had it for several years and still refer to it on a regular basis. He explains things very well.

Make sure you understand the difference between your DC ground, RF ground (for HF radio and to eliminate RF noise in your electronics), and the bonding system that helps prevent electrolsis and may help reduce the probability of a lightening strike or the damage that results if you are hit. People tend to use the word "ground" when speaking about each of these different systems.

On a boat like yours I suspect that the DC ground is the only thing you really need to worry about. If you dont have an inboard engine you can buy a buss bar at the marine store and use it to tie the negative side of your DC system together. Make sure you mount it somewhere that is easy to reach with a screwdriver and not too far from the battery so you dont have to buy an expensive long cable. I cant figure out why anyone makes common slotted screws anymore. Get a buss bar with phillips screws. It might not make a lot of difference when its new but your chances of getting a corroded screw out ( a few years down the line) is much better if its a phillips head screw.

neilio · #5 (**permalink**) 02-25-2003

I found Don Casey''s book very handy.

jheard · #6 (**permalink**) 03-05-2003

AFAIK, on a DC battery system, the ground is the negative terminal on the battery. My boat runs a cable from the negative battery terminal to a bus, which is a copper bar with many places to screw in wires. All the negative wires from my electrical devices attach to that.

elvisnpriscilla · #7 (**permalink**) 03-05-2003

Hi Jheard...where did you mount the neg. buss to? Is it just mounted to a bulkhead or does the buss need to be grounded or mounted to something??