"Glenn Ashmore" wrote in news:tbnlg.112499$Ce1.112216
@dukeread01:

Definitely mount it on the boat. Once you make a place for it to mount
wiring it up is simple but I wish I could find a Charles transformer
for
less than $500. I need two and the best price I have found is $670
each.



Hmm....50A service at 120VAC = 6 KVA.

http://www.charlesindustries.com/main/ma_iso_bost.html
16" x 15" x 12" and weighs 155 lbs....about as much as one passenger.

Can't put it in the bilge where it'll rot in the wet, but try to keep it
as low as possible and near centerline so you don't lean over too far.

Here....justification!:

http://www.charlesindustries.com/main/ma_iso_bost.html

"The Isolation Transformer
The ABYC defines an Isolation Transformer as a
transformer installed in the shore power supply circuit on a
boat to electrically isolate all AC system conductors, including
the AC green grounding conductor on the boat from the
AC system conductors of the shore power supply.
If we are bringing AC shore power aboard to an
electrical panel on a boat, a marine grade Isolation
Transformer should always be used in the shore power
circuit where it comes aboard, and before it reaches the
AC distribution panel or any other device aboard.
The AC shore power current passes through the
transformer's primary windings only, and induces a
current in the secondary windings, which supply the
boat. Primary and secondary windings are insulated
from each other, and a ground fault on the shore side
will not involve our boat.
At its simplest form, a transformer consists of two
coils of wire in close proximity but electrically isolated
from each other, usually wrapped around a common
metal core to contain the magnetic fields produced. If an
alternating current is applied to one of the coils, it will
induce a similar current in the other coil.
Most transformers are designed to step voltage up
or down by having differing numbers of turns in the
two coils. An isolation transformer has the same number
of turns in each coil, serving only to isolate the boat
from the shoreside power, but to give the same voltage.
An Isolation Transformer is used because the shoreside
AC power is referenced to ground. If you are connected
to the earth and you touch the "hot" lead of a normal
shoreside AC service, you will get shocked.
The isolation transformer removes the ground
reference from the ship's service. Neither of the two
sides of an AC circuit on the boat is at ground potential.
Therefore you must contact both sides of the onboard
supply to shock yourself."