SailNet Community

SailNet Community (
-   Electrical Systems (
-   -   Shore power won't engage (

jimd333sail 11-08-2011 11:51 AM

Shore power won't engage
I have an '82 O'day 28 with a 30amp shore power system. In the last few years the double throw switch to connect to shore-side power has worked at first intermittently, depending which dock I used. Now it won't engage at any dock. The boat is primarily a mooring queen and occasionally I like to use the battery charger to fully top off the batteries.

A neighboring boat suggested that I may have a grounding problem. My questions are, where do I begin to find a grounding problem in the AC system; and do those double throw shore power switches "fatigue" or fail that often? There is power to the vessel and the polarity is light is extinguished (as should be). The DC ground is fine.

Thanks for any help you can provide,

Stu Jackson 11-08-2011 05:54 PM

Yes, Jim, they do sometimes eventually fail. Everything has a "useful life." Just buy another one and install it.

mitiempo 11-08-2011 07:26 PM

Or it could be a loose connection that is causing a short between the hot and neutral wires somewhere that is causing the breaker to trip. It might be just doing its job.

I don't think the ground can have much to do with it. The breaker controls hot and neutral only.

jimd333sail 11-09-2011 11:12 AM

If I show 120V on the back side of the double throw switch, then I should assume it is the switch? And where is a good place to go for that switch?

mitiempo 11-09-2011 11:25 AM

Any good marine store should have a 30 amp double breaker. Make sure you buy a proper double pole breaker - you can't combine 2 singles for this.
ANCOR MARINE CE World Double Pole Circuit Breakers for 110V AC at West Marine

Yes if show 120 volts between hot and neutral I would suspect the breaker.

jimd333sail 11-09-2011 11:40 AM

I'll get on it and let you know how it went. Thanks to all, Jim

GaryHLucas 11-26-2011 09:47 PM

Okay, I have lots of shore side electrical experience. On shore you never, ever, not ever break the neutral through a switch or circuit breaker of any kind. There are lots of good reasons for this. Can someone point me to a reference on marine AC that explains why the neutral wire would be broken by a switch on a boat, as mentioned above?


Gary H. Lucas

mitiempo 11-26-2011 11:17 PM

For a main AC switch the hot and neutral are both opened. That way it there is a reverse polarity issue in the marina you can be assured that there are no hot wires. The individual circuits are single pole, opening the hot wire only on most boats. I say most because a friend has a French built Beneteau CC36 that uses double pole breakers for every AC circuit.

On a metal boat double pole switches are often used for all circuits, AC and DC, so when it is off it is guaranteed, for stray current reasons.

All times are GMT -4. The time now is 03:16 AM.

Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
User Alert System provided by Advanced User Tagging v3.1.0 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
(c) LLC 2000-2012

For the best viewing experience please update your browser to Google Chrome