Loop Test - will I blow up?

R

Ronald_M

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Sitting on the boat the other day with my shore lead plugged in - it's one of these:http://www.kampa.co.uk/mains_electrics/pitchpowertrio.html

Just for fun, I thought I'd plug in one of these: http://cpc.farnell.com/socket-see/sok36/socket-tester-earth-loop-rcd/dp/IN05700?Ntt=SOK36

It thought about it for a second or two then the "Loop Test" "CHECK" light/buzzer started flashing/buzzing.

I'm ashamed to say I don't really know what this means (OK I know I really ought to gen up on the subject).

Am I in grave danger??

Ron
 
Thanks, oldsaltoz.

That's more or less what I thought.

My mains "installation", as you will be able to tell, is very basic - just a shore line and a distribution box complete with RCD. I don't have any through-hull metal fittings, so no bonding to earth. My engine is a transom-mounted outboard which has no metal/electrical contact with any other part of the boat other than a dedicated starting battery. When in the marina, the engine is tilted up out of the water, so no earthing via that either.

All this means that my only path to earth is via my shoreline and thence to the marina's earth. My very limited understanding is that it is advisable to have a duplicate "ship's earth" to provide extra reassurance in the event that the shore-side earth is less than perfect.

My socket-tester seems to be telling me that the marina earth might be a little less than 100% pukka.

Time to get my copy of Nigel Calder off the bookshelf??

Ron.
 
My socket-tester seems to be telling me that the marina earth might be a little less than 100% pukka.
Click to expand...

That is what i understand also. Some resistance, rather than a complete open circuit some where in the earth loop.

I think that means somewhere between the point at which the neutral is earthed at the substation, anywhere along the path of of the neutral, to your boat and the tester and then back via the earth conductor to the local earth, then through the ground back to the substation.

If that is correct then about all you can do is check the earth ( and neutral ) connections on your lead.

It might be a good idea, if practical, to try another pontoon outlet and even see what happens if you plug your lead into another pontoon entirely.

I'd have thought by now an electrician would have answered the question!
 
VicS said:
It might be a good idea, if practical, to try another pontoon outlet and even see what happens if you plug your lead into another pontoon entirely.
Click to expand...

Good suggestion, VicS.

And of course if a marina user has any concerns, however misinformed, about the safety of the pontoon electrical supply, there's nothing wrong with politely voicing those concerns to the marina staff. Some marinas might, equally politely, tell you to b*g off and mind your own business(!), although at my marina they are more likely to be grateful to be informed of potentially hazardous defects.

As to the seeming invisibility of "forumite electricians", I can understand their shyness. My brother-in-law recently qualified as an electrician, and is so in awe of all the regulations and certification requirements that he is loth to so much as change a light-bulb for you lest he ends up being sued or whatever. He's now thinking of training to be a plumber.

Ron.
 
wotayottie said:
Odd piece of equipment to have lying around on board, particularly if you dont really know what it is.
Click to expand...

Probably a fair point!

I partly know what it is, however. I bought the socket-tester because I wanted to be able to check the mains polarity (you hear horror stories of live & neutral being inadvertently swapped over) and because I wished to check that the RCD really would trip out before I got fried. These two checks seem to pass with flying colours. The tester just happened to come with a loop test feature as well.

Ron.
 
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