I inspected a home last week that was basically new construction, everything had been stripped to the subfloor, added onto and rebuilt. All new electrical service. There was a GE Main Panel that was labeled as a 100 amp maximum BUT it had a 125 amp main breaker. I know that the panel is overfused and reported it as such but I’m looking for a better understanding. What are the ramifications of such a overfused situation and what may have been some of your narratives concerning this.
BTW the electrician is now wanting to just replace the breaker with a 100 amp breaker saying that he would have to pull another permit to change out the panel. I have further suggested that load calculations be done and shown to the client because I’m thinking 100 amps isn’t enough for a 2400 sqft home and today’s obsession with electronics even if it does have a gas furnace, water heater and range. But then again I’m not an electrician.
Insurance companies can deny any claims associated with accidents resulting from violations of codes.
An 125A breaker in a 100A panel, unless such a thing is permitted in the panel’s legend, violates NEC 110.3 which states that the equipment should be installed in accordance with its listing and manufacturer’s instructions.
But, to your other point, I would not be surprised if 100A service is enough even for a 2400 ft2 house…
If no major appliance is electrical, even with central a/c, 100 amps may be enough.
My 1,500 square foot house barely pulls 30 amps on a “heavy” day.
Doesn’t leave much room for future use IMO. Even if he has to pull another permit, now is the time to do it, not after walls are closed up. Hard to imagine the power co didn’t want to upgrade to 200 amp.
Ultimately it’s up to the owner. I’d ask what is in his contract. I recently had a new home that was planned with 400 and the electrician installed a 200 amp box.
Given that the three big items are gas, 100 may well be adequate. But if they decide to swap out for electric, they may have to upgrade.
As far as load, is add up what circuits are installed and see what’s left over. Most don’t use all they are rated for. Sounds to me though, he is installing the minimum he can. Just my two cents
And…considering he had a 125 in it, the electrician already suspected 100 amps might not be enough
Nice 125 amp distribution panel 
The walls are already in, house is complete…
City inspector green tagged it…but put wrong date…still a month in the future…
100A would be the standard for a 2400 sq ft home in my area.
Talked to a Electrical contractor the other day and he said Home Loads are going way down .
Most equipment now draws a lot less then it used too .
Lighting and electronics are far more efficient now .better windows and more insulation ,smaller more efficient furnaces ,ect.