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Old 12-09-2013, 02:25   #31
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Jeepers what a way to confuse the problem. Reading the OP post , there is no issue with grounds. , even if the AC protective earth wire was commoner between the two circuits , it makes no difference. Commoning the neutrals after the ELCIs will 100 % cause both to trip.

As for other sources of power. Preferably there should be only one ELCI per mains circuit and this should be after all power generation sources , ie shore , generator and inverter. Multi pole switching will be required ( either auto or manual ) to effect changeover of supply and to effect a neutral ground bond for all on boat power sources. A simple auto transfer switch can be constructed out of contactor relays and timers easily enough.

In Europe running parallel mains circuits is discouraged as there is a risk that you plug each leg into different phases of the 3 phase derived 230vac resulting in phase differences on the hots. If you inadvertently then re parallel them , later in the circuit , things go bang.

I would in the OPs case

* seperate the two AC circuits. Including separating the protective earth if possible , but technically not necessary

* if you have onboard generation , wire these into a transfer switch before any ELCIs

* if you want to parallel the two onboard AC circuits when using onboard supplies. You can either add a paralleling set of switch contacts to the transfer switch ( best) , or add a seperate switch ( sorry edit ) before the transfer switch on the local onboard power feed line If this is the case I would add an indicator light to illuminate when the circuits are paralleled .

( ie something like a big multi pole Kraus & Naimer , or US equiv , and switch both AC circuits and at the same time parallel them for onboard generators.

The 30 to 50 amp Y cord isn't an issue. But if you use that ensure the two AC circuits aren't paralleled by the parallel or transfer switch. ( In shore mode ) Alternatively beef up one of the feeds from the shore power to the transfer and parallel switch to handle 50amp and do away with the Y cord. , just ensure the other shore socket doesn't go live. ( more interlocked switches I'm afraid) . The Y cord is probably the simplest method where you have a 50A feed from the shore pillar


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Old 12-09-2013, 02:47   #32
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Re: ELCIs and galvanic isolator

don't worry jim. with comments like this he obviously knows what he's doing.

though I'm kinda curious where the remaining 50a of 240 goes...

Quote:
It also seems to me that a single pedestal could be wired for 240 volts, 100 amps, and broken down at the pedestal. One leg would be 120/ 50, the other leg also being 120/50 and the leg-to-leg being 240. I seem to remember that my mother's house was wired that way. The stove and the dryer were 240 volt. Everything else was 120 volt.
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Old 12-09-2013, 06:21   #33
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Re: ELCIs and galvanic isolator

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Originally Posted by pbiJim View Post
I may be misinterpreting how you have your Y splitter set up, but if it is set up the way that I am picturing, then you probably have pair of 30 amp wires protected by a single 50 amp breaker, which is generally a no-no....As an example, an overload could occur if one of your 30 amp breakers trips & the cable on the other 30 amp cable is chafed to the point of a partial short. In that event, a 30 amp cable could potentially carry up to 50 amps before the upstream breaker trips. That would constitute a fire hazard.

I have seen some scary do-it-yourself wiring in the past & perhaps I am now oversensitive to that possibility.
OK, first off, please understand that theis is not "scary do-it-yourself" wiring. If you look back at the original post, you will notice that I am using a Marinco purpose-built Y-splitter. I even gave the part number so that anyone who was curious could go and look at it, if they so chose. It is just my opinion, but I am fairly certain that Marinco would not manufacture a part that was inherently dangerous, given the possibility of getting sued if it was.

Secondly, your argument is premised on the idea of damage to the cord between the two breakers might cause the line to overload and start a fire. I do agree with that, but my agreement has nothing to do with the relative ampacity of a 50 amp line versus a 30 amp line. A damaged shore power line is dangerous and liable to start a fire. That's why I inspect my shore power cords regularly, cover them with a protective sheath and replace them at the regular intervals. If the cable is in good shape and the connections are tight, the possibility of an additional load on the line, of less than 20 amps, between the two breakers is practically nil.

As for the length of my comments about people hijacking threads, it really wasn't about you - it was about every jerk that has ever hijacked a thread to blow his own horn. It's been building up in my for years. Usually, I don't care too much. If it's not my thread and some jack--- hijeacks it, there's not much I can do. But this was my thread and I wanted to keep it clear.

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Old 12-09-2013, 06:41   #34
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Smac, don't you have a bridge that you are supposed to be hiding under?
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Old 12-09-2013, 06:44   #35
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Thanks, Dave. That is exactly what I have - Blue Sea uses the K&N rotary switch as the basis for their rotary transfer switches and I have the 65 amp, 4 pole, 3 position switch.
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Old 12-09-2013, 07:12   #36
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Re: ELCIs and galvanic isolator

I agree having the ELCI downstream of the genset would provide additional protection, I mention it as some of the early OEM installations of ELCI units had trouble with Inverters etc, so it's something to watch for. It shouldn't be in theory but I have heard a few things from engineers at new boatbuilders. I haven't seen it with any of our customers but there was some mention of it in an ABYC presentation at IBEX last year. I checked my ABYC standards they currently only call for ELCI protection on shorelines and in fact their diagram examples all show the ELCI upstream of the gen shore transfer switch.

ABYC calls for shore power circuit protection within 10 feet of the shore power inlet. Most boatbuilders installing ELCI units will install them separate from the main panel with in the 10 feet to act as both the inlet protection and ELCI protection this tends to put it upstream of any generators and inverters.

I took a look at your blue sea switch I take it you jumped the 120VAC output of the gen to run both shore 1 and shore 2 from one line?

Again the only real problem I see is the combined neutrals. You will need to have all the loads and neutrals for each line correctly placed and separated other wise you can get cross over between the ELCI units causing what your seeing.

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Old 12-09-2013, 07:44   #37
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I did see the 10 foot requirement. My power panel is within that distance of the shore power connections, so I am good there.

As for the rotary switch, you are correct. I have one shore power line connected to points 1 and 5, the other connected to 9 and 13. Then, the generator is connected to 3 and 7, which are then jumpered to 11 and 15. The house load ELCI is connected to points 2 and 6, the other ELCI is connected to points 10 and 14. Hot and Neutral relationships are maintained throughout, with the lower number of the pair being Hot. Points 4, 8, 12 and 16 are internally connected within the switch to points 2, 6, 10 foot and 14, so for my application, they don't get used.

I agree the interconnected neutral buss is probably my problem, so I will split them this weekend and see if it resolves the issue.
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Old 12-09-2013, 07:52   #38
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Yes your good to go. Just ensure when you parallel the neutrals by whatever means such paralleling is made before the elci.

If you can rig it I would always have elcis in the circuit.

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Old 12-09-2013, 09:04   #39
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Re: ELCIs and galvanic isolator

Again, thanks, Dave.

The only time the ELCIs would not be in the circuit is if both shore power and generator are off and the sockets are running on the inverter. The sockets are the only load running on the inverter, the neutral lines from the sockets tie back directly into the inverter neutral out and the electrical sockets will all be GFCI protected (I need to change over one more socket to GFCI to get all of them).

Because all of the sockets tie back to the inverter outlet, and the inverter has an internal automatic transfer switch, I believe that the ELCIs will see this as a "single load" rather than branch circuits.

If I had set up the inverter to feed the entire boat, I would have put it before the ELCIs. However, it only has an 1800 watt capacity, so I didn't want it to be in a position where it would accidentally try to pick up an HVAC unit or the water heater. That happened once before on an inverter/charger that I had and it fried before any of the internal protections could take over.
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Old 13-09-2013, 21:39   #40
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Re: ELCIs and galvanic isolator

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I agree. These are brand-new pedestals - installed within the last month - and I thought the same thing. Why put in one 50 amp connector instead of two 30 amp ones?
Perhaps it might have had something to do with the following excerpt from NFPA 303?

3.13.2
Receptacles that provide shore power for boats shall be
rated not less than 30 amperes and shall be single outlet type


I read that to mean that duplex outlets are not allowed. Perhaps the marina interpreted it the same way.
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Old 14-09-2013, 07:00   #41
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Well, according to the marina, they did it because they were seeing more boats with 50 amp connections, so they figured it was better to let someone split down to two 30s then to split up two 30s to a 50.

Most of their older slips have two 30s, but each one is on its own breaker.
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