Eddy Current
Senior Member
How come in a normal panel the main breaker is less than the sum of all the branch circuit breakers in the panel?
How come in a normal panel the main breaker is less than the sum of all the branch circuit breakers in the panel?
Because it is designed for a particular application, say, for a residence which may not be suitable for another residence.How come in a normal panel the main breaker is less than the sum of all the branch circuit breakers in the panel?
Because the sum of all the branch circuit breakers has nothing to do with the total load the main has to carry.
Isn't that what's feeding the whole panel though?
Yes.
But not every branch circuit breaker is going to be supplying it's marked value, likely none of them will be.
I understand all the circuits won't be used, and even if its at 80% or whatever the code says, that the sum is still larger, but i still don't see how its scientifically possible.
That was Bob's point: It's not 80%. What I mean is that the actual current flowing through a 20 amp breaker is very seldom as high as 16 amps (80% of 20 amps). You might have a 20 amp circuit supplying a bedroom, and all that is on is one lamp and the tv, for a total current of perhaps 3 amps (not 16).. . . and even if its at 80% or whatever the code says. . .
The sum of the ratings of the breakers is larger. But the sum of the currents flowing at any moment through the entire set of breakers will still be far lower than the rating of the main breaker.. . . that the sum is still larger. . .
Eddie, did you write this and post it before or after you read iwire's post? If it was before I would hope that his explanation now clears it up for you.I understand all the circuits won't be used, and even if its at 80% or whatever the code says, that the sum is still larger, but i still don't see how its scientifically possible.
Over here (Australia) the Main circuit breaker is there to protect the consumer mains only.