[Public-list] Re: power hookup

Gordon White gewhite at crosslink.net
Fri Feb 25 04:12:01 PST 2005


I am puzzled by the discussion of problems drawing 15 amps from a 30 amp 
supply.
I assume that the pier has a 30 amp connector, suggesting it is set up 
for a draw of 30 amps.

    If you want to draw less current you are not running any risk at 
all. If you want to plug regular household or garage type cords into the 
supply all you need is an adapter or a cord with a 30 amp marine type 
male plug on the shore end and a standard 3-prong  female receptacle on 
the other.

    If you want to plug a 30 amp shore cord into a standard marine shore 
power receptacle (male) on your boat, as we all do IF we are wired for 
110 volts on board (Albergs weren't wired for shore power when they were 
built)  you need to wire the 110 volt circuits on board to ABYC 
standards, taking care not to create any hazards. In my opinion if you 
want to merely run a battery trickle-type charger (an automatic type 
that cuts off when the battery is fully charged) you run no risk if you 
run an extension cord to the shore power. The charger must be a 
transformer type that isolates the 12  volt current from the shore 
power. Most are, but there were cheap autotransformer battery chargers 
in the past that didn't isolate the two sides.

    You can take from zero amps up to the rated 30 amps out of a 30 amp 
receptacle, no sweat. In fact there is some safety margin and you might 
get away with a few more amps than 30 before the breakers popped. What 
you CAN'T do is get a different  VOLTAGE. If the shore power were 220 
you could not get 110 without re-wiring on the shore side, which I do on 
my pier but you can't do at a marina. However, few marinas offer 220 on 
a pier.
- Gordon White



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