Can I downsize existing A/C breaker?

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Zee said:
GSOHM,
i don't even know what the trip curve is or where to find it. :p I can help by saying it is a 30/50 murray.
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With all the motor loads I'm surprised you don't come up against trip curve issues every day, but oversizing breakers & conductors will make this less important.
 
A trip curve is a graph that show how many seconds it takes to trip a circuit breaker and a given amp load. You may be quite surprised by how high the numbers are (a 20A breaker will probably take hours to trip at 21A and may go forever, and may take 10 to 120 seconds to trip at 40A -- this is from a CH BR trip curve). I was also surprised at the error bars (there are two trip curves -- a min and a max and your actual breaker should be somewhere between those two curves). Not sure if the error bars are due to ambient temperature differences, manufacturing tolerance, or something else.
 
GSOhm, I never install motors, so i have been blissfully ignorant :roll:. Just inverters.

suemarkp, thanks for the explanation. I do know that ambient Temperature affects breaker trip current.
 
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