research generator interlockOK, now I've re-read the original post and see that he wants to monitor "street power" ahead of the main breaker. Agree, a capacitive pickup device like post #3 link is best here, you want nothing contacting said conductors.
But that leaves open the issue that there is no transfer switch in the system, and a dangerous backfeed could occur if the main breaker isn't kept in the "off" position. Highly not recommended.
those work fine and no linemen were harmed in the making
