Searchlight Replacement, wire feeding

[Hotsummerday]

2007 Carver 47 Motor Yacht BMW, I have a bow rail mounted searchlight and wanting to replace it with a LED light. I do know the wire goes through a small section of rail and then drops in my anchor chain box. Has anyone had any experience in feeding wire from a searchlight up to the bridge. Any tips ?

[Midnightsun]

I assume you have a 50A shore power cord connected to the the shore power pedestal? Or, do you have a reverse Y adapter connecting to 2 30a outlets on the shore power pedestal into a 50a cord going to the boat?

[Hotsummerday]

I have a 50A shore power cord, goes through the glendining. Which I have 240V all the way to the panel. Its almost as if the is another breaker/fuse somewhere I just can't pinpoint.

[bud37]

Welcome to the forum.....not that I know what is what, I don't , but I have a question.....do you have an isolation transformer factory installed ?

[km1125]

I don't know about that model specifically, but other boats I've worked on there is a main breaker between the cable spooler (Glendinning) and the isolation transformer (the Charles Smart Boost transformer). In one boat it was a small white electrical box located right between the two units. I would try and follow the wiring from the Glendinning.

Also, between the isolation transformer and the main panel you should either have a selector switch for shore/genset or an automatic transfer switch. Does your electrical system work fine on generator?

I also wonder where you're referencing voltage to. You can measure the incoming 240VAC across the two hot pins, and you should be able to do the same with the output of the isolation transformer. When you say "one leg coming in is normal voltage and the other leg coming in seems to be low voltage", you need to be comparing those to the correct ground or neutral, as incoming VAC has a different ground and neutral than the VAC after the isolation transformer. Also wonder if where you're measuring voltage you're actually seeing power. You can measure trace or "ghost" voltage that's not actually capable of driving anything because it's just an induced voltage. If you put a load on where you're measuring it then you know if there's actually power if the voltage still is present.

[Midnightsun]

The incoming shore power line goes directly to the isolation transformer via a breaker and from there to the panel. If you are getting voltage at the panel this means the isolation transformer is getting power however you mention low power on 1 leg. Sure sounds like something is amiss in the isolation transformer causing it to produce the low voltage on 1 leg. If it were me I would measure the voltage on the 2 outgoing and incoming legs to the isolation transformer. My gut feeling is you are good going in but not so good going out. Unfortunately it sounds like a bad isolation transformer. As mentioned, a quick volt meter test will determine the culprit.

[Hotsummerday]

Thank you all for your input
bud 37: there is the isolation transformer, I'm assuming its the boost transformer
km1125: everything does run fine on generator, there is a main breaker between the glendining and transformer and it is good and on.
Midnightsun: the low voltage is on one leg incoming to transformer

question: when on generator, should it feed through the transformer also?

[km1125]

Source of the post
question: when on generator, should it feed through the transformer also?

No. The purpose is to isolate from shore power, or accommodate variations in shore power voltage. The genset does that stuff by itself, so there's no need for the transformer.

So, how do you switch from shorepower to genset? Is it automatic or manual?

I'm confused by the statement "the low voltage is on one leg incoming to transformer". There is ONLY one "leg" coming into the transformer and that's the 240VAC across both mains. The neutral doesn't do anything there, so there's not really two "legs" like you'd find in a home system or in your system AFTER the isolation transformer.

[bud37]

What is the shore side voltage by the way ?

[Midnightsun]

the low voltage is on one leg incoming to transformer

Then the most likely issue is the cord or the shore power output at the dock or a poor connection/contact in the inlet receptacle of the boat. Have you checked power at the end of the cord before plugging into the boat?