Load calcs for electric Ranges - 220.55

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elec_eng

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This section says "Where two or more single-phase ranges are supplied by a 3-phase, 4-wire feeder or service, the total load shall be calculated on the basis of twice the maximum number connected between any two phases"

I am not quite sure what it means by twice the maximum number connected between any two phases Can someone explain this to me?

I looked up the example D5(a) i Annex D. The example has 10 ranges in 20 dwelling units, 120/208V, 3ph 4w system...It says "the maximum number between any two phase legs = 4" How do they get 4?

Thanks.
 

david luchini

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I looked up the example D5(a) i Annex D. The example has 10 ranges in 20 dwelling units, 120/208V, 3ph 4w system...It says "the maximum number between any two phase legs = 4" How do they get 4?
In the Annex D example with 10 ranges on a 120/208V, 3ph 4w system, they figure that if the ranges were balanced as best as possible, you'd have 4 units on A-B, 3 units on B-C and 3 units on C-A. So 4 is the maximum number connected between any two phases.
 
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