Electric stove load

[Tainted]

I am looking at table 220.55.


Lets say I have (77) 8kW stoves. Do I do the calculation based on columns B and C and see which one gives me the lowest result?

What would the load be with (77) 8kW stoves? Is it 98.6kW?

What about (77) 12kW stoves?

 

[wwhitney]

Lets say I have (77) 8kW stoves.

Do the ranges really have a nameplate rating of 8 kW? One range up to 12 kW is figured at 8 kW due to Table 220.55 Column C Row 1, so 8 kW is often used as a place holder.

For example, I looked up a 20" apartment electric range, Hotpoint RAS200DMWW, and its spec sheet says it is rated 10.6 kW at 240V and 9.2 kW at 208V. I expect that latter value is in error, as it is 10.6 kW * (208/240), when it should be 10.6 kW * (208/240)² = 8.0 kW, so maybe you do have 8 kW ranges.

Although if the voltage is 208V, as your apartments are served by 120/208V "single" phase, you need to follow the second paragraph of 220.55.

Do I do the calculation based on columns B and C and see which one gives me the lowest result?

Yes, that is what Note 3 to Table 220.55 says you may do.

What would the load be with (77) 8kW stoves? Is it 98.6kW?

If all 77 ranges are on the same 2 ungrounded conductors, then 98.6 kW is the value using Column B. Check Column C, the value using it is lower.

What about (77) 12kW stoves?

Well, for column C the value will be unchanged, while Column B no longer applies.

Cheers, Wayne

 

[Tainted]

Do the ranges really have a nameplate rating of 8 kW? One range up to 12 kW is figured at 8 kW due to Table 220.55 Column C Row 1, so 8 kW is often used as a place holder.

For example, I looked up a 20" apartment electric range, Hotpoint RAS200DMWW, and its spec sheet says it is rated 10.6 kW at 240V and 9.2 kW at 208V. I expect that latter value is in error, as it is 10.6 kW * (208/240), when it should be 10.6 kW * (208/240)² = 8.0 kW, so maybe you do have 8 kW ranges.

Although if the voltage is 208V, as your apartments are served by 120/208V "single" phase, you need to follow the second paragraph of 220.55.


Yes, that is what Note 3 to Table 220.55 says you may do.


If all 77 ranges are on the same 2 ungrounded conductors, then 98.6 kW is the value using Column B. Check Column C, the value using it is lower.


Well, for column C the value will be unchanged, while Column B no longer applies.

Cheers, Wayne

how would i calculate (77) 12kW ranges using column C?
And how about if it's (77) 8kW ranges using column C?

Column C is confusing but column B is easy to calculate

 

[wwhitney]

how would i calculate (77) 12kW ranges using column C?
And how about if it's (77) 8kW ranges using column C?

Column C applies unmodified for ranges up to 12 kW, so the final answer will be the same for those two questions.

Column C is confusing but column B is easy to calculate

Column C is even easier, there's no calculation for most of the table entries, the table entry is the final demand.

Cheers, Wayne