How much power does a house need? We’re going to size the electrical service, wires, and panel by figuring out:
You use CEC Rule 8-110 + 8-200 to calculate total "living area":
Mr. Winnipeg Chevrolet builds a mansion that has 30m by 30m dimensions:
30m × 30m = 900 m²/floor
2 floors + 75% of basement (it’s greater than 1.8m in height)
Total = 2,475 m²
Now use the basic load rule from 8-200:
Let’s calculate the floor sizing:
Now, to calculate the total load.
First 90 m² → 5,000 W
The amount leftover afterwards is 2,475 m² - 90 m² = 2,385 m²
Time to list the appliances and equipment!
You’ll use different rules for each item, like:
The easy way to remember what is what:
Let’s total the demand:
I = P/E
I = 47,375 W / 240 V
I= 197.4A
We use 240V because it’s a residential dwelling!
Use Table 2, RW75. 75C Termination Temperature.
197.4A requires #3/0 AWG copper (rated for 200A)
As per usual, Rule 4-006 applies!
Per CEC Rule 14-104:
Use a 200A breaker
"How to Math an Apt" in 8 Fun Steps:
We use 6000W towards the demand calculation plus:
40% of any amount more than 12kW
8000W is what we use to calculate the demand for ONE stove.
But……what if we have more than one stove? Like Mr. Winnipeg Chevrolet who loves to entertain and serve many hot appetizers.
Rule 8-200 1) a) vii)
Consider it an additional load!
The rule to remember is: If it’s HOT, it uses A LOT.
So anything hot (furnace, AC, sauna, hot water tank) will be taken at 100%.
Except (because there’s always an ‘except’ with Code):
Furnace: 62-118 (3)
If the heat is individually controlled: the first 10 kW of connected heating load at 100% demand factor AND the rest of the connected heating load at 75% demand factor.
Interlock is a fancy way of saying that you can’t have 2 or more things all going at the same time.
There are 3 types of Interlock:
Since Heating and Cooling are 2 sides to the same coin, Interlocking can apply here.
If Heating and AC are interlocked, that means you calculate the demand load for both, but ONLY USE THE HIGHEST ONE.
If Heating and AC are NOT interlocked, USE BOTH.
If there isn’t a specific code, and it’s over 1500W, add it all up and take it at 25%.
See? Super easy. Kind of.
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