Another DIYer Transfer Interlock done by Harold Madison, friend of Utterpower. Do note I had trouble wiht the form of the document he sent me, so there’s some cuts and pastes on my part. I love pop rivits, so I would haves used them
This is my interlocking transfer switch arrangement:
Note the main breaker is ON, to the right, and the 50 amp double-pole
breaker (Standby power in) is blocked in the OFF position by the slide.
With the main breaker OFF, to the left, the slide can now be moved up, unblocking the 50 amp double pole breaker which can now be turned ON.
Stand-by power is now connected to the load but cannot be connected to the grid.
Standby Power Cord Configuration
(Has a matching hard wired receptacle to the 50 amp double pole breaker)
Any Questions? Harold might show up to answer them..
115 volt supply from the genset.
Note that the two hot legs of the 220 V plug are jumpered together so both are fed from the same source. They are therefore “in phase” so there is no voltage potential between them. With this configuration any 115 volt appliance in the house can be operated, none of the 220 volt ones can operate. There’s no need to turn off 220 volt breakers.
The refrigerator and freezer stay cold with no cords strung all over; the TV can be used to receive weather reports and monitor weather radar. Another up side of this is any 115 volt light in the house can be used so you can park the flashlight. You do need to pay attention and not overload your standby generator.
My generator is a 2500 / 3000 watt unit that has served me well. With this power limit if I decide to use the electric coffee pot or the microwave oven I need to stop, inventory and make appropriate adjustments if necessary.
OK George; here’s my question:
If this configuration were inadvertently connected to the grid, what would happen?
I believe opposing secondary winding halves in the power company transformer supplying 220 Volt, 200 Amps to my place would smoke my generator with nothing out of the primary to the lines. However, since I never did finish my EE degree, I’m not sure; and I’m not about to try it.