The wiring in the garage dates from the 50s or 60s. There is a breaker box with
a two 15A breakers that feeds the plugs and lights. There is one duplex
receptacle that is wired for 240V - it's hooked up to both hot wires from the
two breakers. The rest of the 120V plugs, etc. come off one of the breakers. The
other breaker is not currently used.
The 240V plug was taped over - I previously didn't even know it was live. I
would like to get access to a 240V circuit. However, I am concerned about the
(existing) apparent mixing of 120 and 240 circuits.
1) Is is permissible to run 120V and 240V circuits off the same pair of circuit
breakers - if they are ganged together?
2) If breakers are ganged together, and one leg is overloaded, are they both
supposed to trip? I performed a little test:
a) with the two breakers separate, an overload (120V) visibly trips one breaker
- the handle moves to the off position.
b) with the two breakers ganged together, the same overload internally trips the
same breaker, but the handles don't move, and the other breaker remains live. Is
this proper behavior? Turning the breakers off, the on again resets the tripped
3) Do breakers 'wear out' or degrade over time? One reason I want a 240V circuit
is I'm experiencing nuisance tripping when running my table saw under load. Is
it possible that the breaker is just tripping prematurely?
4) Should I just leave the the whole existing mess alone, get an upgraded power
drop, main panel and add 240V circuits? This option is MUCH more expensive...
I was looking for the NEC online, but it looks like I have to buy a copy, or see
if the library has one...
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