ranges calculations
- Thread starter gogod
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- Lockport, IL
- Occupation
- Retired Electrical Engineer
Re: ranges calculations
You don't use a "demand factor," but rather read the value directly from the table. But first, if you read through the notes below the table, you will quickly conclude that none apply. Next, look at the headings of columns A and B, you will quickly conclude that neither applies. That leaves you with column C. For 2 identical ranges of the size you quoted (i.e., all that matters is that they are not over 12 KW), the table gives you a value of 11 KW. Article 220.19 tells you that, for ranges, KW is the same as KVA. It?s a single phase item, so current is equal to 11 KVA divided by 240 volts, or 45.8 amps. It?s a continuous load (likely to be running for over 3 hours at a stretch), so 215.2(A)(1) tells you to upsize the conductors by 25%. This means the conductors must be sized for 57.2 amps. Depending on the cable type you use, and thus the temperature rating you are able to apply, you could need a #4 or a #6. If the run is longer than 50 feet, you should also take voltage drop into consideration, and this may require you to go up one more conductor size.
You don't use a "demand factor," but rather read the value directly from the table. But first, if you read through the notes below the table, you will quickly conclude that none apply. Next, look at the headings of columns A and B, you will quickly conclude that neither applies. That leaves you with column C. For 2 identical ranges of the size you quoted (i.e., all that matters is that they are not over 12 KW), the table gives you a value of 11 KW. Article 220.19 tells you that, for ranges, KW is the same as KVA. It?s a single phase item, so current is equal to 11 KVA divided by 240 volts, or 45.8 amps. It?s a continuous load (likely to be running for over 3 hours at a stretch), so 215.2(A)(1) tells you to upsize the conductors by 25%. This means the conductors must be sized for 57.2 amps. Depending on the cable type you use, and thus the temperature rating you are able to apply, you could need a #4 or a #6. If the run is longer than 50 feet, you should also take voltage drop into consideration, and this may require you to go up one more conductor size.
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