100 amp service

[ryandebny]

I'm curious. On a 100amp service how many breakers can I hook up?Can I fill the panel without worrying about overloading it?
Is it based on amperage of each breaker combined?
Is there an equasion for this?

[Speedy Petey]

The combined breaker amperage is a meaningless number. It is not uncommon to see 300-400 amps (or more) worth of breakers in a 100A panel.

[HayZee518]

I have to agree with Speedy about the breakers. for instance, 5- 20 amp breakers are 100 amp but you'll never approach the current rating of the breaker in real life unless you have lots of heating circuits. In the front section of the NEC there are several methods of calculating a service entrance load size. other than architects I know of no contractor that actually uses this calculation.

[Speedy Petey]

I do load calcs when I need to. Usually it is not necessary, experience is enough.

Sometimes if I feel it is close, like between 200A and 320A, and the customer is tight with $$$, I will do an accurate calc.

I would not even consider 100A or 150A on ANY new home or most any service replacement.

[HayZee518]

Speedy - I had one dwelling in massachusetts that was sooo big I had to use three sub panels. The main was a 200 amp - two subs were 100 amp and one in the garage was a 60. I did that mostly for economics. The home runs were so far from the main, it worked out using the subs.

[Speedy Petey]

Originally Posted by HayZee518

The home runs were so far from the main, it worked out using the subs.

A perfect reason to use subs.