100A 120/240V panel at combo - but main breaker only has 100A?

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zeefrank

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Canada
I am using right now:

Dryer - 3,000W
A/C or heating- 3,000W (minimum)
Oven - 5,000W
Broiler - 3,000W
Water Heater - 3,000W
Fridge/dishwasher/tabletop top/broiler/lights/microwave/etc - up to 4500W
Other appliances (hair dryer/PC/etc) - not in use when I work

I have recently started a small cooking business. COVID and all. I am afraid I am overloading my circuit.

I have a 100A 120/240 panel, typical here. This should imply I have 24,000W of panel. I have balanced my 120V appliances between the two legs on my panel.

According to my calculation, my max power draw, if everything runs at once, is 21,500W, which is way below the 24,000W limit. I should be fine, right? I also overestimated some W, oven very rarely pulls 5,000W (and waster heater isn't always on)

My issue is - I took at look at the main breaker, aka the one in the basement of the building, and it has a big "100A" on it. Is this because it brings 100A at 240V to me (24000W total)? Or do I have only have "100A 120V"=12,000W in my unit?

In other words, the main breaker, in the electrical room of our condo - does it bring up 100A of 240A to me? Can I fully use 24,000W of appliance power (or 80% of that anyway)? I use dedicated lines for each appliance.

I know this doesn't sound ideal but that's all I have. I am afraid to start a fire or cause problems. I use the oven A LOT and same for other appliances.

OFC I am not using them full time, but according to my electricity provider, I am using around 370KWh a day (!!!!). Obviously not using the appliances at night much (some of them however).

Thank you.
 
You should contact a professional (licensed electrician) to perform a proper load calculation. Simply adding up the major loads isn’t the right way to do it.
 
You are probably fine. The breakers are there to protect the circuits in case you overload them, assuming a proper installation. If you were overloading them they would trip.

It might be a good idea to have someone knowledgeable come out and take a look. Sometimes there are non-obvious things that might need to be dealt with. But if the installation was done correctly and you are not tripping circuit breakers you are probably okay. The important thing is the installation was done correctly originally. If some hack did the work it may have not been done correctly and the circuit breakers might not trip on overloads. There's just no way to tell you with the information that you can give us whether it is a safe installation or not.
 
zeefrank said:
My issue is - I took at look at the main breaker, aka the one in the basement of the building, and it has a big "100A" on it. Is this because it brings 100A at 240V to me (24000W total)? Or do I have only have "100A 120V"=12,000W in my unit?
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The former. You can look at it as 100a/120v + 100a/120v = 100a @ 240v.
 
LarryFine said:
The former. You can look at it as 100a/120v + 100a/120v = 100a @ 240v.
Click to expand...
Plain and simple is that it is 100 amps each pole whether it is amps from 120 volt loads, 240 volt loads or combination of both.

Load line A with 50 amps of 240 volt loads and you will also load line B with same 50 amps. Then add 75 amps of 120 volt loads to A but only 25 amps to B and you are right at total VA allowed, but are overloaded on the A line and it will trip if it remains that way for long enough time.
 
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