T&T: Power Cord

[Peter Bennett]

Monday, July 28, 2008, 9:01:50 AM, Gary wrote:

GB> I agree entirely up to this point.  My 50 foot 30 amp 120 volt
GB> cables cost $79 and weigh a mere 15 pounds each. A pair of them
GB> will connect two separate 30 amp 125 volt outlets on the dock to
GB> the two receptacles onboard.  My power panel provides for
GB> separating the 125 volt load into two separate circuits (they
GB> still share the same neutral and ground) so I can use a total of
GB> 60 amps.  Where only one 30 amp 125 volt outlet is available I use
GB> only the one cable, I switch the panel to parallel the two
GB> circuits and then have only 30 amps available aboard.  The panel
GB> provides an interlock gizmo that prevents paralleling the circuits
GB> while both plugs/cables are used -- because one cannot know
GB> whether the two 30 amp 120 volt dockside outlets are out of phase
GB> with each other, virtually canceling each other -- or not, where a
GB> 'ground loop' risk could exist.
GB>
Both ABYC and the Canadian Standards Association require that separate
shore power inlets _must_ be isolated - the neutrals must not be
connected together on board.  This is, I think, primarily a safety
precaution to protect against incorrectly wired dock outlets, where
hot and neutral may be reversed.



-- 
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