453 Electrical system

Hi,

Your problem might be simply the fact that 125v + 125v doesn't equal 250v.

A single phase AC Connection is comprised normally of 3 wires, Phase, Neutral and Earth. Even if you have 4 or 5 of these connections you will only have an increased current capacity ( at the origin anyways) not an increased voltage.

I was once trying to buy a cooker in Ft Lauderdale for a 240V Boat, the tech who came to fit it assured me 240 was simply two lots of 120. He was sent away to do some homework and we fitted it ourselves.

Are you sure it is 250V you need and that is not just the rating of the socket/plug you have?

What voltage lights and electric motors do you have onboard?

There are a few electrical guys who post here who might be able to explain this in terms you can understand.

what problem are you having? no power at all on one or both of the legs? low voltage? popping breakers? hard to reply to your post without knowing the symptoms.

The most important thing when it comes to shore power is to reduce loads and the turn off the main breakers before connecting and disconecting.

typically, I shut down the Air Con breakers, water heaters and otehr signigicant loads, then switch the main breakers and rotaries off. On the dock side, i shut off the main breaker and then disconnect the cord.

never disconnect under load as this will cause arcing. Never turn / swtich your rotaries with a load as it will cause arcing on the contacts and eventually cause issues.

Obvioulsy, keeping the contacts clean, dry and using dielectric grease is always a good idea too.

if your dock pedestal doens't have a 120/240-50 outlet then you have to use a smart Y and tap two 120/30 . the smart Y ensures that each 30amp outlet is on opposing phase and will only activate when both plugs are in and on opposing phases.

obvoulsy, with a smart Y you are limited to 30amp on each leg instead of 50amp. you will still get 220v (30amp only) to power whatever 220v loads you have on the boat like Oven, dryer, air con or water maker.

but again, what are the symptoms? throwing parts at a problem is never a good approach.

"A single phase AC Connection is comprised normally of 3 wires, Phase, Neutral and Earth. Even if you have 4 or 5 of these connections you will only have an increased current capacity ( at the origin anyways) not an increased voltage."

actaully, here in the US if you connect to two outlets and the hots are on opposing phases you will get 240v between the two 120v hots.

when using a single 120/240-50 cord, you have 4 wires: Ground, Neutral, and two hots. you will have 120v between each hots and Neutral, but you will have 220v acorss the hots.

US 220v is different from europe. Over there you have 220v between Hot and Neutral.

Yes, you can use dielectrical grease without any issues whatsoever.

Most of the time arcing in connections is caused by trying to draw too much amperage for the supply size/connections. Many boats that utilize a 50 amp shorepower cord, could draw 70-80+ amps at a time, if you run everything and anything all at the same time. For example if the hot water heater is going, all a/c's have the condensors running and the stove and washer/dryer.......Many times when I use a heavy draw item like the stove/over or washer/dryer, I'll shut an a/c off or something else. Make sure you're never drawing more then 50 amps on your electrical panel.......I have seen many Y's that have had the ends fried off of them as well as many 50 amp cords melt the end where it plugs in on the dock from too much amp draw.........Another good measure is to feel the cord near where it plugs in at the dock and see if it's warm.......

Doorpro, When I manage a transient marina awhile back we had more than a few boats come in with "smart" Y's that arced and popped breakers like crazy. DK what the deal was, but the regular Y's worked with no problem.
2nd thought, do you have a voltage isolater on your boat?

all the smart Y does is ensure both legs are on and connected to opposing phase before kicking in. Like eveything else, the arcing is caused by hot dis/connects under load.

the reason why boats using smart Y pop the breakers is probably because they need to keep the loads under 30amps instead of 50.

I use smart Ys on our 2 125/250-50 cords once in a while, at marinas that don't have twin 125/250-50, works fine, no issue beyond having to manage the loads.

I think Pascal has hit the nail on the head. Using the smart Y you are going to get 60 amps of 120 VAC at the most. That is effectively half of what you are going to get with the 50 amp cable which should provide 100 amps of 120 VAC. Load shedding is the answer. Run half as much load (on the watt meter) as you would ordinarily and you should not get damaged contacts.

The "gel" you want to use is actually an anti oxidant of which there are many. Petronox is one i like but any anti ox will do. The term dielectric is very confusing as a dielectric is a non-conducting substance. If there is such a thing as a dielectric gel and there probably is, don't use it!

Ted