Example No. D1(b) One-Family Dwelling

Assume same conditions as Example No. D1(a), plus addition of one 6-ampere, 230-volt room air-conditioning unit and one 12-ampere, 115-volt room air-conditioning unit,* one 8-ampere, 115-volt rated waste disposer, and one 10-ampere, 120-volt rated dishwasher. See Article 430 for general motors and Article 440, Part VII, for air-conditioning equipment. Motors have nameplate ratings of 115 V and 230 V for use on 120-V and 240-V nominal voltage systems.

From Example No. D1(a), feeder current is 78 amperes (3-wire 240 volts).

 

Line A

Neutral

Line B

Amperes from Example No. D1(a)

78

61

78

One 230-V air conditioner

6

6

One 115-V air conditioner and 120-V dishwasher

12

12

10

One 115-V disposal

8

8

25% of largest motor (see 430.24)

3

2

2

Total amperes per line

99

83

104

Therefore, the service would be rated 110 A.

*(For feeder neutral, use largest of the two appliances for unbalance.)






Pocket Guide to the National Electrical Code 2005
Pocket Guide to the National Electrical Code(R), 2005 Edition (8th Edition)
ISBN: 0131480014
EAN: 2147483647
Year: 2004
Pages: 120
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