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From: Steve Weingart (gate.net!shw)
Date: Tue Oct 01 1996 - 15:24:55 EDT
Marc,
>Re:Grounding the AC to the DC system. I don't know what is best. Several
>books that I have read encourage floating the AC system off the DC and
>leaving it ungrounded. As I have been unable to locate all the ground
>sites on our boat I have been unable to do this and have had to leave all
>the AC grounded to the boat's ground. I believe that if you do this it
>becomes fairly imperative to isolate the boat's AC from shore. We have an
>isolation transformer which does this. Is this correct?
Isolation is definitely the best way to go, so few folks have this because
of the cost and weight of the transformer, that I never mentioned it.
If you are isolated, tying the isolated A.C. ground to the D.C. boat ground
is correct (I just looked it up in the section of the ABYC spec that a kind
person gave me). The green shore power ground wire may variously be tied
to: nothing, the isolation txfrmr case, or the txfrmr isolation shield
depending on the setup.
Isolation txfrmrs are the best way to keep things safe and prevent galvanic
action. If you want to go one step farther, put a GFI breaker on the output
of the txfrmr and the system will be really safe.
BTW, without txfrmr isolation, floating the AC gnd is crazy IMNSHO, it can
float to dangerous levels, especially at some of the shoddily wired old
marinas that I've been to. (I'm not including the use of a galvanic
isolator here, that only isolates the first .6 volts and prevents corrosion,
but does not isolate not larger voltages)
Cheers,
Steve
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