<html><head></head><body><p dir="ltr">What sort of cable? Is it possible that the power supply common is being connected to chassis ground through the cable shield?</p>
<p dir="ltr">Sean<br>
</p>
<br><br><div class="gmail_quote">On July 27, 2015 4:33:32 AM MDT, James Frankland via Personal_Submersibles <personal_submersibles@psubs.org> wrote:<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<div dir="ltr"><div>Hi All</div><div> </div><div>I have a very peculiar issue. I have an earth fault on the boat. </div><div> </div><div>My test consists of holding one probe of the meter on the positive battery terminal and the other to the hull somewhere. I was showing a reading of 24v. So obviously a negative connection somewhere to the hull.</div><div> </div><div>I went around everything taking things off and have tracked the fault down to the lights.</div><div> </div><div>The lights are the trustfire ones and the negative connection is grounded to the chassis of the light. However, when I fitted the lights, I was aware of this and so insulated the mounting bracket from the light casing itself with a piece of rubber. So theoretically, there is no physical connection from the case to the hull. Only the internal wire.</div><div> </div><div>Anyway, if I disconnect the lights and leave them dangling on their wires, there is no earth fault. The lights all work,
and the hull is clean of current.</div><div> </div><div>So the lights must be leaking back through the connection somehow, but I cant see how. The case is insulated from the mounting bracket with rubber and the brackets are connected to the fibreglass faring, so it shouldn't leak back?</div><div> </div><div>Anyway, ive fixed it by insulating the mounting bolts with delrin washers, but I cant see how the earth could return through a piece of rubber and then glass fibre. A mystery unless anyone can see something obvious?<br /><br />Regards</div><div>James</div><div> </div><div> </div></div>
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