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Old 28-01-2014, 11:39   #1
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GFCI Vs ELCI

Electrician (French and French boat) asked me to bring RCD for my inverter. I asked blue sea for the part numbers and they replied it wasn't necessary to install and with information about GFCI and ELCI breaker.
The shore supply is protected by panel as photo
I have 2 inverters for a new install
1 2500W 110V
1 2500W 230V
the 230v is replacing an existing unit. The 110V will be a new circuit maybe 2 circuits to enable use of US standard appliances.

Any advice what i should carry to Panama, not much available there.

Thanks
Paul
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Old 28-01-2014, 11:43   #2
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Re: GFCI Vs ELCI

Depends on your ground system as to whether a GFCI or move correctly a RCB would provide any real additional protection.

Dave
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Old 28-01-2014, 17:09   #3
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Re: GFCI Vs ELCI

I am just trying to understand how it works. Mastervolts require a RCD.
Is this not the same thing as a GFCI?
But the mastervolt has only 2 wires
Only ground I see is to the shore power but if we are not plugged into the dock I guess we don't have ground?

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Paul
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Old 28-01-2014, 17:31   #4
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Re: GFCI Vs ELCI

You only need the two wires. An RCD/GFCI measures the difference in current between the hot wire and the return (neutral) wire. There should be no difference, since the current going out should be the same as the current coming back. If it's not, then the current is flowing someplace it shouldn't.

GFCI receptacles are frequently used in wet locations where there is no PE (ground) as in old buildings, etc. If a person forms the path to ground and conducts current the GFCI will detect the flow as not coming back along the proper path and open the circuit.

[Edit]

With regard to RCD/breaker, RCDs/GFCIs can be standalone equipment, or they can be built-in in a breaker. The breaker gets wired a little differently (the neutral has to be connected to the RCD breaker rather than just to a neutral bus). If you are only protecting one piece of equipment you might use a local RCD. If you are protecting everything on the circuit you could use an RDC/GFCI breaker. [/Edit]

[More Edit]

Your picture of your main shore breaker shows that it is an RCD type breaker. The little circle around the two wires on the left of the diagram is the differential current detector. The "30 mA" on the label indicates that the breaker will open if the measured differential is greater than 30 mA. Unless your equipment specifies that it requires a separate RCD you already have one on the entire system (which can sometimes be a pain if run leaky equipment, but is a good safety feature). [/More Edit]
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Old 28-01-2014, 17:48   #5
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Re: GFCI Vs ELCI

Thanks I think that means my 230v side is protected.
The 110v side has no connection to the shore power only batteries to inverter to ac outlets.
Can I just put a GFCI in the 1st position and let that cover the circuit
Thanks again for all your help
Regards
Paul
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Old 28-01-2014, 17:52   #6
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Re: GFCI Vs ELCI

And RCD on an invertor when the boat is off shore power provides very little if any real protection. Since earth, aka sea water is not in the current path then touching the hot invertor wire will not cause any shock nor cause a RCD to trip.

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Old 28-01-2014, 17:52   #7
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Re: GFCI Vs ELCI

Not having seen your installation, it is probably what I would do. Even with no connection to shore power, the RCD measures the difference in current flow and is intended to detect when the flow is not balanced (as in flowing through a person rather than the wires). Depending on how the neutral is wired on the boat you may or may not have a ground path that includes boat pieces and/or water. Given that that is an unknown to me, an RCD/GFCI breaker is cheap insurance to make sure you (or worse, your wife or guests) don't end up as electrical conductors. If you install it as the main 110V AC breaker then it will protect everything downstream.
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Old 28-01-2014, 17:54   #8
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Re: GFCI Vs ELCI

And there you have it. You've asked the internet and gotten two opinions 180 degrees apart
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Old 28-01-2014, 17:59   #9
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GFCI Vs ELCI

Quote:
Originally Posted by Dsanduril View Post
And there you have it. You've asked the internet and gotten two opinions 180 degrees apart
Sure I'm a 20 year professional industrial electronics engineer with power supply , and inverter design in my portfolio. I've rewired several boats. The other opinion is ......

I'm all in favour of such devices , but you must be aware of how these systems work and what real protection they provide.

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Old 28-01-2014, 18:08   #10
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Re: GFCI Vs ELCI

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Originally Posted by goboatingnow View Post
The other opinion is ......
From a registered engineer (1991) who has designed, installed, commissioned, and performance tested > 2GW of DC-AC conversion systems. No real experience though.

Oh, and both a licensed electrical contractor and general journeyman electrician.

To the OP, you can value it however you would like to value it.
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Old 28-01-2014, 18:18   #11
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Re: GFCI Vs ELCI

Quote:
Originally Posted by Dsanduril View Post
From a registered engineer (1991) who has designed, installed, commissioned, and performance tested > 2GW of DC-AC conversion systems. No real experience though.

Oh, and both a licensed electrical contractor and general journeyman electrician.

To the OP, you can value it however you would like to value it.
Well that's ok then.

Maybe it's time for a serious look at neutral wiring in inverters. Then the protective earth circuit. I personally prefer fully floating neutrals in that any boat should be completely safe with reversed polarity. ( it's very common to have floating neutrals in Europe )

But the debate may be a bit too esoteric for CF. lol

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Old 28-01-2014, 18:40   #12
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Re: GFCI Vs ELCI

I probably agree with you about floating neutrals (and the esoteric nature of that discussion). However, IME boats are rarely wired 100% properly. And even those that are at one point frequently end up not so after additions/deletions/changes by various owners and third parties.

The whole point of an RCD is to detect current flow through unexpected paths. Even with a floating neutral, if there is a difference in current flow the RCD will do its job. On a boat with a floating neutral a return path could be created by something as simple as condensation, especially in a salt water environment.

Given that 10 mA will cause muscular contraction, and breathing starts to become difficult at 20 mA, it doesn't take much of an alternate path (even a moderately high resistance one) to put one down for the count (or forever). To me, cheap insurance against future unknown conditions. If I had equipment that was giving me a lot of nuisance trips then I would consider that in both the decision and the system design.

To each his own, YMMV.
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Old 28-01-2014, 18:49   #13
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Re: GFCI Vs ELCI

I fully agree , a standard 30 ma RCD at my local B&Q is about 30 quid , on that basis always worth fitting

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Old 28-01-2014, 19:01   #14
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Re: GFCI Vs ELCI

I couldn't find anything like the breaker in the photo for 230v in the local Home Depot or lowes. All I could find were the outlets.
Blue sea will sell me the panel but it looks like that is designed to deal with shore power.
My boat is a 2007 French cat. The electrician is French and he didn't seem worried about the inverters. But we have a language barrier therefore I wanted to ask some advice.

I think that it's probably not needed but it doesn't look like it will do any harm to add the GFCI so I will

Many thanks for all the advice.

When the boat gets back to the US I will have a marine electrician give me a 2 nd opinion
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Old 30-01-2014, 08:19   #15
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Re: GFCI Vs ELCI

Thats a European style Din rail breaker they are pretty much only used in industrial wiring here in the US. In Europe as mentioned by Dave they are cheap and easy to get here in the states not so much. From your description it sounds like you will have a simple inverter system for 110 (no shore power) if that's the case no ELCI would be required but GFCI protected outlets would be required in galley outdoor wet spaces etc. You can either protect the outlets with a GFCI breaker (a bit hard to come by in the states) or with the GFCI outlets.
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