AC fault

[pjcomeau]

I seem to have the original 1988 AC breakers/panel and I'm having a problem (ground fault).

I plugged the AC to a GFCI plug at the boat yard (we have access to AC during winter storage). and the GFCI at the source tripped. I assumed It was because of the water I got over the winter.

After a few weeks of drying everything up. I decided to try the AC again. Same problem. So I started tracing the problem.

One of the previous owners introduced a GFCI outlet/plug at the nav station/panel and therfore changed how the remaining outlets were wired at the panel so every outlet is part of the GFCI circuit. After different attempts at isolating the problem, I tought I had it down to bad outlets (when they were removed from the system the GFCI at the source did not trip).

So I replaced the outlets I tought were bad (including the GFCI at the nav station). Still did not work.

I removed everything from the AC wiring and only left the main breaker and the new GFCI (line in only, no out load to other outlets). I also removed all other connections from common bus.

I make sure the breaker is turned off at the nav station, then plug the AC outside. I turn the breaker on, the light on the GFCI plug turns green and everything stays up. I then plug a lamp to the GFCI plug (a light that I plug directly on the same extension cord fine) and the GFCI trips at the source (not the nav station).

Before I rip wiring out, is it possible the main AC breaker is the problem? I'll also have to look at using an ohm meter to check for fault (I used the approach and thought I had it track down to outlet, I will have totry again).

Thanks,

Pierre

[Jon Schneider]

Are you in the water? How are you connecting to AC?  Same way, same cable that you normally use?  Or are you connecting via a 15A-to30A step-up socket?  That could be the problem.  Are you sure the marina's AC is properly grounded? 

[pjcomeau]

I'm not in the water. I'm using a 30A to 15A adapter (which is all our marina will offer when boat is going to be in the water).

I know the conditions may not be the best, but I've been able to plug all sorts of items on the extension cord directly without tripping at the source (e.g. 500w lamp / heaters...). Even in very wet conditions.

Everybody else (including me in another boat) uses this arrangement fine (i.e. turn AC on).

Is there a way to check the breaker? What about books saying the polarity light connection can give false reading (when testing for ground).

I will try the new GFCI outlet on the always live side (i.e. no breaker) and see if the outlet alone trips the source (that will eliminate the wiring from 30a/15a adapter to inside wiring to breaker). And go from there.

-PC

[pjcomeau]

Problem resolved!

Since I just wanted to "verify" the AC system when I started this process, I just used the extension cords I was already using (strung through the companion way).

Tracing back the problem, I found that one of my extension cords (the newer one, I never would of suspected) has a problem. I'm very green so I was following Don Casey's instruction on checking wiring. Using the ohm meter and testing ground to ground on both end of the extension cord, the reading was zero (so I thought it was OK). But If I put AC on extension cord and check voltage, that's when thing go interesting; I got ~120v on hot/ground, but got maybe 60v (or less, did not look at actual number, I knew it was wrong) on hot /neutral and neutral/ground. I wasn't sure what it meant other then the extension cord is bad (every other test gave me the expected 120v, 120v, 0v).

I reconnected everything (except hot water for now, I still have to check this out). and everything tested OK.

-PC

[Ron Hill]

Pierre : FYI, the GFI was installed at the factory. 
1988 was the first year that Catalina's had a factory installed GFI for the AC outlets.   

[Mike Vaccaro]

Another characteristic of GFI's in the marine environment is that they can trip in conditions of extended periods of high humidity, simply due to their sensitivity.  They will work normally when things dry out. 

Mike