370 / 375 - Short circuit interior lights

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Short circuit interior lights

Printed From: myHanse.com
Category: Hints & Tips
Forum Name: 370 / 375
Forum Description: 370 / 375 Hints, Tips and News
URL: https://www.myhanse.com/forum_posts.asp?TID=15490
Printed Date: 27 March 2026 at 03:29
Software Version: Web Wiz Forums 12.06 - https://www.webwizforums.com

Topic: Short circuit interior lights

Posted By: Dimitri
Subject: Short circuit interior lights
Date Posted: 10 January 2026 at 12:29

Hello everyone, we have quite a problem here with one of our Hanse. Some time ago the line of interior lights on the port side got a short-circuit. It's definitely somewhere after the electric cabinet and lamps, cause I disassembled every lamp and pulled every wire I had access to with no luck. Tried moving and shaking cables along the port side - no effect, short circuit seems to be stable. Neither visual inspection for random screws gave any clue.

Does anyone have an idea where junction box might be located on our boats? There are definitely some, at least one that separates aft and fwd parts of the line, but I have no idea where to look for.

Any advice on how to move forward is appreciated. Thank you!

Replies:

Posted By: Arcadia
Date Posted: 10 January 2026 at 13:32

Before I can advise you need to clarify if this is a SHORT circuit or an OPEN circuit. Sometimes these term are used interchangeably. They are very different conditions!

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Leon / ARCADIA
2018 Hanse 588
Sag Harbor, NY

Posted By: Dimitri
Date Posted: 10 January 2026 at 15:51

Short circuit - 0 Ohms resistance to ground (negative battery terminal). When trying to switch on circuit breaker it flips back off immediately.

Posted By: Dimitri
Date Posted: 12 January 2026 at 11:43

Update: Without any intervention on my side, the short circuit seems to have “auto-repaired.” One morning it was simply gone and the lights started working normally again. Unfortunately, this has happened before, so I don’t consider the issue resolved.

Once the circuit came back, I tried tapping on every panel/door/cabinet on the port side and shaking cables to see if I could reproduce the short and narrow down its location. No luck—nothing I did triggered it.

The only difference I can think of is temperature. I had been heating the boat with the Webasto and left the water heater on for a couple of days. Maybe the warmth caused something to expand/shift (a wire, connector, or screw) and the short disappeared.

In any case, I’d really appreciate help identifying the cable routing on this circuit and the locations of any junction boxes/connectors I should check.

Posted By: Mark_J1
Date Posted: 15 January 2026 at 14:07

On the early 400 most of the wiring for the main saloon port side lights comes from the forward bulkhead and is strung behind the headliner panels. Forecabin & aft cabin wiring rises behind the wardrobes. There is a messy set of cabling from below the breaker panels routing fore and aft behind the cabinetry. The riser to the main saloon is behind the port side wardrobe in the forecabin and routes up to and along the top of the bulkhead through an embedded channel. Comes out at the mast foot.

Perhaps you can isolate the wiring at the mast foot and do some further checks? It is a very awkward job running fresh cables but I have done it! :) Good luck.

Mark

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Hanse 400e "Grey Goose" Hull #31

Posted By: sgrhma2
Date Posted: 15 January 2026 at 20:05

On my 370, which is one of the very early ones, I had a problem in rough conditions with taking water in through the swan neck at the base of the lights. This caused the trip for the port side to trip as water around the forward port bulkhead light short out. I ended up having to rewire, change the switch and bulb holder in light unit to fix the fault. As Mark says, it might be worth having a look in this area. There’s a thin ceiling panel that runs across the top of the bulkhead in the fore cabin that the wire drops down from to the light.

Hope this is useful

Simon

Posted By: sgrhma2
Date Posted: 15 January 2026 at 20:07

Sorry, base of the mast, not light🙃