Single phase cooking equipment on 3phase service

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Simple enough.
There are three phases, AB, AC, and BC.
Each range connects to exactly one phases.
If you connect six ranges to each phase you have a total of eighteen. You must add two more ranges, leaving seven on two of the three phase.
Seven is greater than six.
If you did not do your best to distribute the loads equally among the phases you could have more than seven max. But the Code gives you the benefit of the doubt. :)

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Welcome to the forum.

benjkohl said:
The question in the book is
What is the demand load for twenty single phase 14kw 208volt ranges on a three phase service?
Step 1: Determine the maximum number of ranges between any two phases: 7 units

How do you determine the 7 units?
Click to expand...

I fixed that one typo, changing "or" to "of". GoldDigger already showed the way. Another way to see it is take the # of appliances (20 in this case) and divide by the number of phases (3), and round up any remainder. 20/3 = 6.666....., which rounds up to 7.

For the rest of the steps in your test question, you would be using table 220.55.
 
If you had a single phase feeder that had multiple cooking appliances on it - those would all be on "one phase" when considering load on upstream three phase feeder or service conductors.
 
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