Making a generator interlock kit

Ignoramus32538 · 2005-01-26T22:45:33+00:00

I am considering making a generator interlock kit. What it is is amechanical device that engages both the main breaker in the electricalpanel, as well as one of the individual circuit breakers near the mainbreaker. Its purpose is to prevent both breakers from being on at thesame time.It is not difficult to imagine one, there would be a flat piece cutoutenclosed in some rails that would move and permit the circuit breakerto be engaged only if the main breaker is in the down position.I would write up exact drawings on paper and make it from 1mm thickgalvanized steel sheets that I scrounged somewhere. One challenge isto make sure that the flat piece slides in something very smoothlywithout getting stuck. It would be hels from the sides by some"channels". I would like some ideas on how to make very smoothsliding combination of the piece and the holder.Any thoughts will be appreciated. I can write up and post drawings ifmy explanations are poor.For an example of an interlock kit see

Jan 26, 2005 41 Replies

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But I thought the ground reference at the service entrance was, according to you, unreliable and could not be counted on.

Because the ground and neutral are still bonded at the service entrance, a hot-to-ground fault can still bring the ground lead to the pole up to some potential and harm a lineworker.

According to that scenario, nothing short of interrupting *all* *three* *wires* between house and pole will suffice.

Because I know that most commerical transfer switches don't do that - they only interrupt the two hot legs - I can only surmise that the particular failure mode you discuss is not an issue in the real world. If it were, then those transfer switches would not be code-legal.

Jim