The Latest in “Creative” Marina Wiring

[ItDepends]

Anyone who has traveled to marinas around the world, knows that the electricians who wire them are a very “creative” breed. We have all see reverse polarity, missing grounds, high resistance grounds, bad neutrals, high voltage, low voltage, etc, etc. But this was a new one on me…

I was working with a client who was having electrical problems recently, and while I was helping him troubleshoot, I saw in his pictures something that had me scratching my head. On an island I knew had USA standard 60Hz power, the power pylon on the dock had standard European style 240V/32A/50Hz outlets. Huh?

Well, they were actually wired as split phase 120V outlets, with two hots and a ground. For boats that use 220V power this would WORK, but aside from the unexpected frequency, this wolf in sheep’s clothing just might just give them some nasty surprises.

My boat is an older, 220V boat. The circuit breakers installed in the branch circuits are all single pole breakers. If that shore power was connected to my boat, all kinds of trouble would ensue. Not right away, but in the event of a fault.

If there was a short to ground in a branch circuit, the breaker would trip, just as expected, but only one of the hot wires would break. The short would continue being feed from the other phase, the wire the boat designer expected to be neutral! A recipe for a fire.

The chances of the various ground fault devices working properly are not good in a split phase system. Some might, but certainly not all.

Finally, somebody unmindful of the issue, might easily set off to work on a circuit after throwing the breaker. They even check for voltage between hot and “neutral” and, seeing none, then go poking around with tools and fingers in a system that is still hot with 120 Volts to ground.

I know that people use a 120/250 feed all the time in lieu of single phase 220V power. The difference there is that they KNOW what’s coming, and hopefully were smart enough to have double pole breakers everywhere, and other things properly configured for that kind of power.

[tkeithlu]

I can think of two morals to your scary story.

1. Always check all the combinations of wires for voltage, or
2. Unplug the boat before working on a circuit.

Thanks for sharing it.

[goboatingnow]

Anyone wiring a euro boat cannot and should not assume neutral is “ dead”. Neutral must be treated which equal respect as if it was a live wire.

[ItDepends]

Originally Posted by goboatingnow

Anyone wiring a euro boat cannot and should not assume neutral is “ dead”. Neutral must be treated which equal respect as if it was a live wire.

That's true of ALL single phase wiring on any boat. Reverse polarity is way too common, both on the dock and on the boat, and there are many, many other faults both on the boat and in the marina that can leave dangerous voltage on the neutral wire.

Any time I open a panel on a boat, I assume every wire (including the green ones!) can kill me. Too many boats have been modified by too many clueless people to trust that ANYTHING is right.

On my boat, if I need to plug into a 110V dock, power comes in as single phase and is bumped up by the isolation transformer. Everything, everywhere, is always single phase. Other similar boats do bring in the split phases from a 125/250 outlet. That's fine--IF your boat is configured for it, and you are aware of it.

This setup by the marina is just a clunky and dangerous way of advertising that they have 220V power at the dock.