RickB
Guru
- Joined
- Oct 20, 2007
- Messages
- 3,804
- Vessel Make
- CHB 48 Zodiac YL 4.2
On the live plug, the scenario I had in mind is gen running and shore power NOT plugged in. If you turned both breakers on, the prongs at the shore power inlet would be live and dangerous. And if you connected your power cord to that inlet, then the shore-end of the cord would now have live pins exposed.
That is the reason there is an interlock. Unless the boat is equipped to allow paralleling of power sources there must be a mechanical interlock to prevent both sources from being connected to the buss at the same time. The OP asked why there is an interlock, that is the reason.
If you are interested in electrical safety then you must consider the sequence of events when switching between shore power and generator power and follow them. There should be no means (interlock) or reason (forgetting to do something) that will create a hazardous condition. If the exposed prongs are energized, either the boat is not properly equipped or the use is not adequately prepared to handle that procedure.
Why would anyone handle an energized shore power cord in any event? The boat end and shore end breakers should be open until the boat (and the user) are prepared to receive shore power. The shore end breaker should be closed first so that the supply can be verified at the switchboard and only then should the shore power breaker on the boat be closed. That procedure provides several opportunities to confirm that all is in order and avoids handling any energized components.
Guns and cars can be dangerous to those who don't know how to operate them, boats can be dangerous as well, electricity is no different, we are not talking about unknown territory and we are not talking about building codes or house wiring rules.