On 2006-11-25 13:43:55 +1100, "mortond" said:

Hi,

Sorry, I guess I wasn't as clear as I thought!

The marina only has a 50 amp receptacle.
I wanted to avoid the cost of buying a second 30 amp or a single 50 amp
isolation transformer.
Basically, I wnted to hook-up the convection oven and fridge to the 50 amp
shore power receptacle, like an extension cord, except, the extension cord
would be routed via a 30amp breaker on the boat (revised that from a 50
amp) to one leg of the 'Y' branch of the shore power cord.
The appliance grounds would not be connected to the boat at all. I assume
the shore power ground would be isolated from the boat by the existing
isolation transformer on one leg of the "Y" and because there is no boat
connection on the other "Y" leg.

Thanks for the interest.

David

Here in Australia a major manufacturer of fibreglass cruisers has a
dual inlet system. This is because virtuall all marinas supply shore
power at 240VAC 16A single phase. Some marinas do supply a limited
number of berths with 32 A single phase or 32A 3-phase power. The said
manufacturer supplies these dual inlets predominently on 40' or larger
and factory fitted air conditioned boats. The two feeds are brought to
the AC switch panel and there is generally a facility to parallel the
loads so that a single feed can be used subject to shore power delivery
capability.

I have observed the same system being used on Benneteau power cruisers
which have factory fitted air conditioning.

Your boat being steel requires that you do it right! If you need
separate feeds to accommodate the demand then put in two feeds and two
transformers. To do anything less is both foolish and shortsighted. The
life you save may be your own!

P.S. I am a boat owner and an EE with an Electrical Contracting L/C.

--
Regards,
John