T&T: Power Cord

[Peter Bennett]

Monday, July 28, 2008, 7:45:33 AM, Patrick wrote:

<snippage>

PAMC> Now to the marine 50A, connector.  It also has two 120V lines 180 degrees
PAMC> out of phase.  If you have a single 50A cable running to a 50A connector on
PAMC> your boat, the two lines will be split at the boat's electrical panel and
PAMC> the electrical load will be divided among the two inputs.  If you use a 50A
PAMC> to two 30As splitter at the dock supply, this is where the two 120V lines
PAMC> are split.

The marina may be wired for three-phase power, in which case the
voltage between the two hot wires in a 50 amp 120/240 outlet, or on
two 30 amp outlets on different phases, will be 208 volts rather than
240. This may be a problem if you have any 240 volt electric motors on
board.

PAMC> The point of this lengthy, and probably confusing discussion is that the
PAMC> 50A ckt breaker on the dock is not a single breaker with a 50A rating.  It
PAMC> is actually a double breaker composed of two 25A, or maybe 30A, breakers:
PAMC> one for each 120V source.  So in realty, you're getting the same overload
PAMC> protection you would get from being connected to two 30A dock connectors.

No - the breaker feeding a 50 amp 120/240 volt outlet will be a two
pole 50 amp breaker - effectively two 50 amp breakers in one package,
arranged to both trip at the same time - it will safely pass 50 amps
on _each_ hot wire without tripping.

PAMC> I hope this helps.

PAMC> Patrick
PAMC> Ft. Myers, FL 

-- 
Peter Bennett, VE7CEI    Vancouver, B.C., Canada
Ennos 31 "Honeycomb"
GPS and NMEA info: http://vancouver-webpages.com/peter 
Vancouver Power Squadron: http://vancouver.powersquadron.ca