100 amp sub-panel
#1
01-21-16, 12:26 PM
100 amp sub-panel
Hello all - this is probably a very basic question but it's something I'm curious about. We had a 100-amp sub-panel put it as we're in the process of finishing our basement and needed more circuits. The sub-panel has room for about 15-20 additional circuits. My question is, what does the "100-amp" refer to? Does that mean I can only have 5 20-amp circuits or 6 15-amp circuits in the box? Or does that just mean the most it can handle is 100-amps all at one time (that would be a lot, right)? Thanks!
#2
01-21-16, 12:58 PM
Forum Topic Moderator
If fed by a 100 amp breaker you could run up to 100 amps at 240 volts or 200 amps at 120 volts. Many houses run on less than 100 amps.
#5
01-21-16, 02:00 PM
The amp ratings printed or stamped on the handles of the breakers (e.g. 15, 20, 30). In other words, a 100A breaker panel can support many more than 5 20A breakers due to the fact that branch circuits do not operate at 100% capacity for extended periods of time. The electrical code provides a formula called a "demand load calculation" to figure out what the realistic capacity of a panel is.
#6
01-21-16, 02:22 PM
And of course the breaker supplying the panel can be less than 100 amps. It isn't uncommon to use a 100 amp panel on a 60 amp breaker just so you have enough space for all the breakers. All the 100 amp designation means is that is the maximum amperage it is rated for.
#7
01-21-16, 06:59 PM
Member
All the 100 amp designation means is that is the maximum amperage it is rated for.
we're in the process of finishing our basement and needed more circuits.
#8
01-21-16, 07:07 PM
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I have a 200 ampere service. Between the service panel and two sub-panels I have at least 900 amperes worth of circuit breakers. I doubt that I have ever pulled as much as 100 amperes through the main CB.
