Quote:
Originally Posted by Piotrsko
195 amps worth of breakers doesn't imply the 200 amp box is near capacity. Your 200 amp box simply means that's the most it will provide before probably the main breakers open. If you total up all the breakers in my 70 year old box, it is double the 100 amp rating but the probability of drawing 100 amps at one time is miniscule since the stove, water heater, HVAC, dryer only total up to 75 amps. That gives me the availability of 25 + amps for surge on start.
Oddly, here in Reno it is space for breakers that determines whether or not you can expand. Most everyone adds a sub box and moves a pair of breakers to that
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I'm curious - what happens if you exceed the total amperage of the box - and there is no master breaker?
The box in this house is unlike any other house I've lived in as the breaker box doesn't have a master breaker[/B] that feeds power to the rest of the panel. Instead there is a 200 amp line that comes straight into the box to the hot bus bar. The top of that box has 6 openings for the 220 circuits. One of those 220 circuits has a 60 amp breaker that connects to the bottom half of the box and connects to 2 sets of bus bars for 12 110v circuits. If that bottom half is overloaded it will trip the 60 amp breaker.
As far as I know there is no protection on the top half of the box. There is space for 1 more 220 circuit. I could run a new 60 amp circuit to the 48 amp EVSE. That would be 255 amps of breakers. If I decided to run the charger, dryer, stove, heat pump, and hot water heater at once I could exceed the 200 amp service coming into the house but never trip any of the individual breakers. I would just overheat the main service line and risk a fire.
I can't image that meets code. (It also creeps me out a bit that work done on the top half is done live)