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INTEGRA Bespoke Lighting
03-20-2010, 09:00 PM
Question for our EC friends.

Im on a Yacht and when the captain powers up the LV underwater lighting system we get an electrical issue at the beverage cooler (you get a shock when you touch the cooler). Both the cooler and the lighting transformers are powered by the same 120V circuit. So something is happening between the primary side of the LV transformers and the cooler unit. They have tried to run a separate isolated ground back to the genset and this had no effect.

Any help would be appreciated.

INTEGRA Bespoke Lighting
03-20-2010, 09:16 PM
Addendum: They have tried putting an in-line GFI block on the primary side of the LV transformers. The shock situation still exists and the GFI does not trip.

RLI Electric
03-20-2010, 09:39 PM
Multiwire circuit with a possible ground touching neutral? The gfci may not pick it up. Not familiar with any type of boat wiring but I am assuming you are not on a Boston Whaler

emby
03-20-2010, 09:45 PM
Polarity is reversed somewhere. You are energizing the the shell and all metal parts of the fridge.
Does the fridge's cord have a 3 prong or 2 prong end on it? Or is it hardwired?
If the fridge's cord has a 2 prong plug pull the plug out of the receptacle and reverse it when you plug it back in.
Let me know what you find out.

Ken

INTEGRA Bespoke Lighting
03-20-2010, 10:08 PM
Polarity is reversed somewhere. You are energizing the the shell and all metal parts of the fridge.
Does the fridge's cord have a 3 prong or 2 prong end on it? Or is it hardwired?
If the fridge's cord has a 2 prong plug pull the plug out of the receptacle and reverse it when you plug it back in.
Let me know what you find out.

Ken

The cooler uses a 3-prong grounded plug (this is a commercial bar fridge we are talking about). As do the LV transformers for the underwater lights. Using a TRC Portable GFI / splitter to power the two loads. Cannot understand why the shock situation exists and the GFI is not tripping. Have tried replacing the GFI unit with a new one and same situation.

Baffling.

INTEGRA Bespoke Lighting
03-20-2010, 10:10 PM
Multiwire circuit with a possible ground touching neutral? The gfci may not pick it up. Not familiar with any type of boat wiring but I am assuming you are not on a Boston Whaler

Nope, not a Whaler... 85' DeFever M.Y. Check out my avatar photo.

RLI Electric
03-20-2010, 10:26 PM
If you unplug the xfmrs and turn on the receptacle that powers them, does the problem still persist?

RLI Electric
03-20-2010, 10:27 PM
Or if you unplug the xfmrs and put in a table lamp and turn it on, is there still an issue?

Gr1ffin
03-21-2010, 11:12 AM
Not to derail, but tell us about the yacht... I've seen it as your avatar for a while now and wondered why the choice. Is it yours, friends, family? Where kept/do you cruise on it? Very cool.

Re your prob I don't have an answer but as a boat owner:
-there is limited room on a boat and options for chasing wires, plus they are not put in conduit like a home. Add to that the vibrations and jarring on the open seas and it can result in chaffing of the insulation off wires where they are pinched/rubbed. I would follow the primary circuit that feeds the LV transformer and see where it is in contact with the ground wire from the outlet for the fridge.

Alan

mgm
03-21-2010, 01:33 PM
The neutral and the ground may need to be connected (bonded )together at the 110/120 tap on the xformer or generator , if the gfci does not trip it is either defective or the neutral is not grounded , if the system is ungrounded you should have only 2 wires at the outlet in question and the gfci will not work.

Pro-Scapes
03-21-2010, 06:00 PM
James,

In my youth and teen years I grew up in the California delta. All thru my teen years I made hundreds of dives on yachts ranging from 28 ft to 80 plus feet and I ran into a similar situation

On a raft out (several boats tied together and anchored in the river basically to have a big party) our friends 50 ft Chris Craft ran over our anchor line. after his boat was secured I made the dive to cut the rope from his prop. I pulled out my knife once I was underwater (I knew I should have had a rubber handle) but once I touched the strut with the knife I got a kick you could not imagine and was lucky to be able to get back to the swim platform only a few feet away.

Turned out he had a hot chassis on his ice maker. The door on the ice maker and the inside was plastic so it never became the problem you are having until it was pulled out for service and the tech servicing it got nailed. Replaced the ice maker and problem was solved.I assume there was some sort of short inside this possibly from a condition similar to Alan is explaining.

Something else to consider. Is this condition limited to shore power or also when on generator power ? You need to isolate the problem by removing parts from the equation. Have you tired putting a volt meter between the fridge...and ground...nutral...power on the lights...any voltage ? Changes ??? Swap in a temp LV transformer ?

INTEGRA Bespoke Lighting
03-21-2010, 07:06 PM
If you unplug the xfmrs and turn on the receptacle that powers them, does the problem still persist?

Or if you unplug the xfmrs and put in a table lamp and turn it on, is there still an issue?

Thanks Bob... The problem only occurs when the LV transformers are plugged into the circuit. Unplug the trans. and there is no issue at all. I am suggesting to them we try a different LV transformer and see if that works.

INTEGRA Bespoke Lighting
03-21-2010, 07:13 PM
Not to derail, but tell us about the yacht... I've seen it as your avatar for a while now and wondered why the choice. Is it yours, friends, family? Where kept/do you cruise on it? Very cool.

Re your prob I don't have an answer but as a boat owner:
-there is limited room on a boat and options for chasing wires, plus they are not put in conduit like a home. Add to that the vibrations and jarring on the open seas and it can result in chaffing of the insulation off wires where they are pinched/rubbed. I would follow the primary circuit that feeds the LV transformer and see where it is in contact with the ground wire from the outlet for the fridge.

Alan

The NSS Pattam is a 85' DeFever MY that we have chartered for our 2010 Family vacation. So far, all of our expectations are being surpassed!!! What a fantastic trip! Check it out at www.nsspattam.com Mat and Pat (along with Scott) are giving our family the vacation of a lifetime. Highly recommended.

INTEGRA Bespoke Lighting
03-21-2010, 07:16 PM
James,

Replaced the ice maker and problem was solved.I assume there was some sort of short inside this possibly from a condition similar to Alan is explaining.

Something else to consider. Is this condition limited to shore power or also when on generator power ? You need to isolate the problem by removing parts from the equation. Have you tired putting a volt meter between the fridge...and ground...nutral...power on the lights...any voltage ? Changes ??? Swap in a temp LV transformer ?

Thanks Billy... the electrical issue is only when the yacht is on generator, which for us is 24/7. Obviously we wont get into much of it while on vacation, but I thought some more insight here from others would help the Captain to isolate the issues.

If I get restless, I might take a stab at installing a new LV trans set on the lights. The kids would to see the tarpon surfacing in numbers.

RLI Electric
03-21-2010, 07:50 PM
Sounds like a ground fault on the seconday side of the transformers that the gfci cannot see.

Pro-Scapes
03-21-2010, 08:31 PM
The volt meter and a bit of detective work is your friend here. You would be surprised at the things you can find with a volt meter and continuity tester.

I think there is definatly a short either in the secondary side of the trans (12v shorted to ground) or an issue on the secondary side outside of the trans. Put an amp meter on the secondary wires then grab the fridge :)

David Gretzmier
03-22-2010, 09:42 AM
curious- when plugging anything else into the wall socket where the trans is plugged in, does it have the problem? perhaps the act of plugging anything in at that plug completes the circuit and causes the short to happen. also, I would try plugging in the cooler at a different outlet. - same result? I would isolate if it is only those two plugs, only one of the plugs, only the trans, only the cooler, etc. perhaps you have tried this?

David Gretzmier
03-27-2010, 03:12 AM
James? been a few days. any answers?

INTEGRA Bespoke Lighting
03-27-2010, 07:13 AM
Our last morning in Paradise (for now). Never did get the time or inclination to solve this one. I am pretty sure the Captain is going to switch out the LV transformers and put the new one I recommended on it's own circuit.

If any of your are looking for a "Vacation of a Lifetime" (seriously) I highly recommend that you book a week with Pat and Mat aboard the NSS Pattam. www.nsspattam.com They have exceeded our expectations at every single turn, and the food, my God the food!!! Five Star all the way.

RLI Electric
03-27-2010, 07:29 AM
Do you know of a transformer or aftermarket product that can gfci the secondary side?