I’m wiring the A/C outlets on my 36 Nonsuch and I’m having a problem I thought I’d ask for your help. The wiring from the panel goes to a GFCI outlet and then to the rest of the outlets on one side so that they’re all protected. When I flip on the breaker though, it trips the GFCI outlet that I’m plugged into on the shore power pole. I’ve tried several other new GFCI outlets and they all do the same thing. Even wired with just the GFCI outlet alone, same thing.
If I wire a regular outlet in place of the GFCI, nothing trips.
Hi Bob, if one of your outlets downstream of the GFCI is wired incorrectly that’ll cause the GFCI to trip. For instance a loose ground in one of the outlets would do it.
Ron
Ron & Diane Schryver
“Alpha Waves” '87 NS30U #393
Georgian Bay Midland ON
Your question interested me so I took a look on the web.
Is it possible that the breaker on the shore power pole is an ELCI? If so, and your galvanic isolator is “old style” and has a self test function, that can trip the ELCI.
You said in your first post that if you replaced the boat’s GFCI receptacle with a standard receptacle that the shore breaker would not trip. The terminal screws on a GFCI breaker will be closer to the wall of the receptacle box than a regular receptacle will be as the GFCI receptacle is wider. If the box is metal, is it possible that a terminal screw on the GFCI is touching the receptacle box?
The box is non-metallic, so nothing is touching. Even with the outlet out of the box it still tripped. I’m thinking that I have the A/C wiring wrong on the bus bar. I thought that the neutral and the ground on the A/C side were supposed to be on the same bus bar for the galvanic isolator (which is new) to work properly. I’m now thinking the A/C neutral needs to be separated from the ground bar. That’s probably why it’s tripping. Thoughts on that?
Should the A/C ground and the DC ground all be connected?
The galvanic isolator should only be installed with an interruption in the green ground wire, the white and black should not be connected to the galvanic isolator. Then they should be connected to your AC main breakers at your distribution panel and then to individual circuits.
Steve Currier
Nonsuch 36 Caper
Thames Yacht Club
New London, Ct.
On boats, when connected to shore power, the ground wire and neutral wire must not be connected.
The exception is that when powered by an inverter, the receptacles that are powered by the inverter have their neutral and ground supply automatically connected together inside the inverter. Once shore power is applied, the inverter disconnects the neutral to ground connection.
So, yes,I believe your latest supposition is correct.
All good advice. I would add that since you are re-wiring anyway you might consider adding an onboard ELCI. It’s basically an ultra-sensitive GFCI but it will soon become a very handy if not imperative piece of the shore power system. As marinas convert to ELCI outlets you may find that a small leak in your system, too small to trip your GFCI, will trip the marina side ELCI. If you decided to pay moorage for the night to charge batteries, that would leave you “in the dark”.
Having an onboard ELCI insures that you will find that leak before any of the other unpleasantness takes place rather than having you scrambling at the marina slip trying to isolate the it.
I installed one this year and fortunately it proved that I have no leaks. It did however have one quirk that I should point out. If you have an automatic transfer switch for an inverter and it defaults to inverter, then the momentary leak that accompanies tripping the relay to shore power will trip your ELCI. The solution is to either arrange to have the switch default to shore power or what I do which is simply unplug the inverter, reset the ElCI, and plug the inverter back in.
Given the real risk to people posed by ac circuits it is worth having a qualified and competent marine electrician ( not a residential or commercial electrician) do a survey of your system, They can identify any issues, answer questions and you can decide whether to fix them your self or have them do the repair.
We need to remember what Edison said, A/C will kill and DC is safe!! As a child growing up in a tenement in Manhattan we had DC until I was about 10 and is why I was unable to have electric trains until 1950.
Joe Valinoti
S/V iL Gatto NS30U #221
Sea Harbour YC
Oriental, NC USA
That was marketing. Edison and Tesla had very different and commercially competitive ideas about electricity.
It is the current that kills, not the voltage or frequency. There are factors which make AC more dangerous than DC at a given RMS voltage, but 120VDC is only slightly safer than 120VAC and will kill you dead under most circumstances that AC will kill you.
Fortunately, we are dealing with 12VDC here on most of our boats which is very safe because of skin resistance. Though still not completely safe. Unfortunately, beneath your skin is a body full of salt water which is a pretty good conductor. So if you happened to stab a frayed copper wire on your 12VDC bus all the way through the skin on one arm and a frayed copper wire on the ground side through the skin on your other arm, you could have fatal amounts of current passing through your heart or spinal column and you’d be toast. If you find this hard to believe, just stick a 9V battery on your tongue. That current isn’t going through your heart or brain or spinal cord and it is applied outside of your (wet) skin, but you sure will feel it.
On the other hand, I have placed a wrench on a 440VAC bus bar in a tug boat (I was told by the electrician that it was off!) and it blew me about three feet through the air. It did not kill me because I was dry and my shoes were apparently well insulated from the steel deck. So I did not get a deadly amount of current through my body. But I sure did feel crappy for a couple of days!
I test for power by poking my wife. Everyone is surprised at how long I’ve lived, too.
He probably had dry skin and good boots. High resistance in the “circuit” (your body, in this case) reduces current to safer levels. I bet he never did it with wet hands or outdoors on a rainy day. Pros tend to know what they can get away with and what they can’t and often take shortcuts that really aren’t a good idea. I knew a commercial electrician who routinely identified circuit breakers by jamming his screwdriver between the hot screw on a socket or switch and the ground wire in the box. That’ll pop a breaker, for sure, but it’s not at all recommended. You end up with arc marks on your tools and on the screw and the arc to the ground wire reduces its diameter (gauge) and makes it brittle. But it saved him a minute or two.
For $32 on Amazon, this 600 Volt, CAT III meter will measure just about any AC or DC electric value you can desire. It has a non-contact voltage detection so you don’t need to hook up the leads and touch the leads to terminals to detect the presence of power. Just hold the tip near the wire in question and push a button. If voltage is present, the meter will give an audio and visual report. A real finger saver.
If you buy a meter, get a 600 volt, CAT III for safety.
Everyone should have one of these in the house, vehicle and boat.
The drawback is it is made in China. Hopefully, technology innovations can allow manufacturing to return to North America.
