ECN Forum Forums Code Related Discussion NEC & other Code issues Panel maximum?

US Electric utilities have an insane number of standards with respect to transformers, and if those of the distribution variety fail, the likelihood of a quick, cookie-cutter replacement is good.
http://standards.ieee.org/catalog/olis/dtransformers.html

I think Andy is trying to ask:
"If my main panel is 200Amp main and i have a 100A subfeed, 30A stove, 40Amp range, 40Amp A/C, and (10) 20amp single pole breakers and still room in the panel to pull additional circuits can i do that? Or i will max out the panel?"

I think that is what he is trying to ask.

Edward

Yes that is what he is asking and I do not think it can be answered here with the info given.

We have no idea what the connected load of the 100 amp sub feed is, an AC unit with a 40 amp breaker does not draw 40 amps and 10 20 amp SP breakers do not draw 200 amps.

There are only two ways to answer this.

1)Take real load measurements with an amp clamp. On a large job we would put in a data logger for a few days to a week.

2)Do the load calculations from the NEC.

I was just at a commercial job looking at a 400 amp panel with six 200 and two 100 amp 3 phase breakers in it (1400 amps total).

Was this panel maxed out?

I would have to say no as it has been that way for many years.

Actually, what Andy is asking is how would you determine if this panel or any existing residential panel is maxed-out already, per the NEC. I believe to be absolutely sure I'd have to take the current readings for actual demand and calculate (per NEC) the pool equip. and the A/C equip. loads, since it's off-season for them. This overall existing load together with calculated load of the future living space should tell the story.

For business sake, we'd want to sell an upgraded service if justified, right? But, maybe our competitor is hinting that it's not really necessary for the additional circuits. Now you have to make your case.

What's your opinion?
Andy