Electrical Ground Question/Advise

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bartender66

New member
We have a 2006 25' C-Dory. I am in the process of installing a new am/fm radio and am not sure where a good place to ground it would be. I'm not an electrician by any strech of the imagination however I do know if you don't get the ground right it's not going to work. Any suggestions/advise would be appreciated. Thanks in advance!

Terry
 
I've had a Sony marine am/fm/cd hooked only to the the two main panel busses (+ and -) with it's own inline fuse for 2 years with no noticeable static or problems of any kind. It sits on a wood overhead bench. This is from memory but I'm sure if it had a separate ground wire, I would have simply wired it to -. My panel is wired to the house bank.
 
My 06 has a Blue Sea fuse panel on the back of the control panel just below the steering. I don't know if it is a C-Dory installation, or not. Mine has an empty fuse location on it - no wire connected to the screw terminal. Connect you "hot" (red) wire here. If you have the same, the top section of the fuse panel is for negative (ground) connections - the wires to this section SHOULD all be black. Connect your ground (black) wire here.

Your mileage may very.
 
The automotive radios have a chassis ground. Anyplace on the metal chassis is grounded. It used to be that there was no "black" wire, and one had to ground the chassis to the negative bus. Most radios now have a black wire--and that goes to the negative bus. Every boat owner needs to have a digital volt meter, and that way you can determine what wires are positive and which are negative.

As far as working--if there is a black wire, and you install that to the negative bus (black wires to it--and the orange and red wires to the positive side of the battery, the radio should work fine.
 
On my boat the negative bus...think it is properly called a 6 gang terminal block. If i recall correctly here are six brass screws on both sides of the molded base with the main negative wire attached to one side of the base. Curiously when i used a tester with a light to see where the power was there was no ground( power connection ) on the side of the negative bus where the main negative wire wasn't attached but only to the side of the bus where the main negative wire was connected....I would think both sides of the negative bus would be grounded. Is is correct or did i do something wrong. Thanks Tug
 
Tug, I am trying to picture what you are saying. My 87 isn't anything like that. Mine may have been changed many times.

But generally there shouldn't be any power to the negative buss. It is simply a common connecting point for the negative side of multiple circuits (kind of an extension of your batteries negative post). I think both sides of your negative buss (if you have more than 1) are most likely tied together or bridged somewhere, maybe on the back where you can't see?

The only place you are going to get a test light is bridging a positive and negative source, creating a circuit. If you get a light from one side to the other then one side is not a part of the negative buss. It may be a positive buss, or simply a buss for the common splicing of several same polarity wires within a single circuit (as in running 4 lights in the cabin off one switch).

Going one step farther, if you test your light from your known positive buss to the side you know is grounded, it should light. If you test it to the other side it should also light if that side is part of the negative buss. If it does not, it is most likely a positive polarity buss (which could be switched off or on) and I’d trace it.

When you figure it out, labeling it and making note in your log is probably a good idea. I took several hours a while back to document my electrical and label as much as I could. I told my wife it was for the next guy, but alas, I fear it’s more likely for me.
 
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