Difference between DC grounding and DC - bus

clayhubler

clayhubler

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C Dory Year
1986
C Dory Model
26 Pro Angler
Vessel Name
Merlin
What is the difference between the two bus bars on the back of this panel and what would be the most common reasons for these to be separate? It is a paneltronics circuit breaker panel.

Thanks

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Great question. I can't wait to hear the answer myself.
 
Normally you would see that in a setup that a +DC and a -DC supplies (e.g. +15v, -15v). So you have the two voltages and a DC ground (which is used for shielding and if you only needed one or the other of the voltages on a load.

On a 12vdc boat, I don't know what it would be used for. I'll bet that both the DC ground and the -DC voltage gets tied back to the negative battery terminal somewhere.
 
A slight expansion on what ssobol commented. The "Green wire" in a boat is often DC ground (somewhat different than AC ground). It is for shielding of various electronics cabinets, and in some boats it also ties the thru hull fittings together.

For true RF shielding such as for an auto pilot when running high power SSB rigs, we use copper foil (about 1 mm thick and 2 to 3" wide. This gives far better RF shielding than just a wire.

As ssobol notes these all also go to the negative of the battery.

The only C-Dory I used this type of ground on was my Tom Cat 255, where I had a 100 watt SSB radio.
 
Thanks everybody. Should I just tie these together then for a larger negative bus?
 
No reason to tie together unless you need more terminal posts.
 
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