AC Leak

[zboss]

Folks,

By recent turn of events I recently discovered I have an AC leak on my boat.

Worse yet, it seems to be leaking into my DC system.

I recently (almost three years ago) had my AC electrical system - up to the panel/charger/batts - brought up to standard with a new ELCI and larger gauge wiring with proper terminations. This was done by an ABYC Marine Electronics company in Maryland. I did not touch it.

In the process of upgrading my plumbing system I came across an unknown courtesy light under my sink where my hot water heater resides. It was an original mini-halogen that was tucked up out of sight and it appeared to be burnt. Since the rest of my courtesy lights had already been upgraded I counted my luck and started to replace the light with a new LED version.

When I touched the wire I got a mini-tingle even though the power was turned off. Not anything severe but enough to go... "hm... why am I getting a tingle with the power turned off".

After hooking up my meter and doing some investigation I discovered that when the lights are switched off I am getting a 60 Hz current in the DC line... American Boat AC. With all DC off in the boat I am getting .4 volts on this particular DC wiring.

1. I checked a few other DC circuits that fed through the DC panel and they read a lot less stray voltage; four devices go directly to the batteries and the courtesy/emergency lights are one of them - those devices are seeing .9 volts. The rest of seeing about .1 volts stray 60 Hz current.

2. I turned OFF the AC circuit at the dock pillar and the signal went away.

3. Tested the ELCI and the signal went away.

4. I turned OFF the AC main switch on the boat circuit breaker panel and the AC signal went away.


So... I'm sure its my boat.

5. I went through each of my boat AC switches and determined that two of three of my AC outlet branches are leaking but one in particular.

So, remedial action is to replace all the devices on those branches (two outlets each) and check again. Last resort is replacing all the AC wiring from the worst offender and see if the problem goes away.

MY TWO QUESTIONS....

a) I am also trying to trace down a problem with my SSB receive/transmit (it is "new" and I have never gotten it to work properly)... even when we are not on AC shore power, can leaks like this be the cause of my issues?

b) How is it that devices hooked directly to the batteries would be seeing more stray current but items that go through the electrical panel see much less?

c) How the HECK does ac current find its way into my DC system?

Also, any other suggestions of things to check would be helpful.

[a64pilot]

Silly question, except for possibly ground, there should be no place where AC and DC connect?
Except for the battery charger?


Sent from my iPad Pro using Cruisers Sailing Forum

[zboss]

Originally Posted by a64pilot

Silly question, except for possibly ground, there should be no place where AC and DC connect?
Except for the battery charger?


Sent from my iPad Pro using Cruisers Sailing Forum

I would imagine so.

The only thing I can think is that somewhere the AC ground in the branch is somehow connected to the AC hot and sending the AC to ground. You would think this would trip the breaker or the GFCI but it is not.

This is why I am starting with the devices - in case there is some sort of failure mode, like corrosion in the outlets.

[zboss]

I have been doing some research... apparently this is a situation that just kinda slipped through the fingers of ABYC regulations. European boats have a much lower voltage tripping standard than US boats.

I'm going to take the time and upgrade my outlets to the newest standard - UL 943. Also, I'm going to replace the metal outlet boxes with Hubbell Marine weatherproof type.

New wiring, new outlets, new outlet boxes. That should take care of the issue!