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	Subject - Can breakers arc? BillA Living in an area prone to basement flooding (waste lines actually back up into basements ), several of us have generators to keep the water out should power go out as well. We were discussing long term outages since the old-timers here said power was out once for a week and they had radiator pipes freeze and burst (they run out outside house walls). We were discussing the last resort method of connecting a generator to an outlet to run the heating circulators and boilers AFTER shutting off the main (100/200A) breaker. This would be needed because a boiler/furnace doesn't have a plug. I realize there are transfer switches but we're talking of something that may happen once in 50 years. Besides stressing that you can't ever screw this up for fear of facing criminal charges for backfeeding into the grid, I suggested there could still be a problem if there is arcing across the main breaker. Of course someone said if there could be arcing, then killing breakers while working on wiring could be dangerous if arcing occurred while working on the inside wires. This made sense. So to my question is, can main or branch breakers arc (excluding because of lightning)? Scott Vickrey It takes about 80,000 volts to jump 1 inch in your average air. The voltages you are talking about using will never bridge the open breaker. There are rules about this and I'll have to get back to them later. BillA Thanks Scott. I'm curious how much the arc voltage drops versus humidity. I had an old car as a kid (ok, high school) which ran really poorly in high humidity or rain - even stalling. I suspect humidity in the distributor cap had something to do with that. Scott Vickrey As for your car, I'm sure it did. You have to use a transfer switch if your wanting to hook the generator to your electrical system. This is for the safety of the linemen out there working in bad conditions to get your power back on. It is even in the 2002 code(section 700.6).