Heat Star Systems 7547 Mentor Ave., Ste. 304
Mentor, OH 44060
Ph: (440) 701-1031
Fax: (440) 918-1120
 
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AMP Calculation for Control Selection

  Single Three Phase Balanced
Heater
Wattage
120V 208V 240V 480V 208V 240V 480V 600V
500 4.2 2.4 2.1 1.1 1.4 1.2 0.6 0.5
1,000 8.4 4.8 2.1 2.1 2.8 2.5 1.2 1.0
2,000 16.7 9.7 8.4 4.2 5.6 4.9 2.5 1.9
3,000 25.0 14.5 12.5 4.2 8.4 7.3 3.7 2.9
4,000 33.4 19.3 16.7 8.4 11.2 9.7 4.9 3.9
5,000 41.7 24.0 20.8 10.4 14.0 12.1 6.0 4.8
6,000 50.0 28.9 25.0 12.5 16.7 14.5 7.3 5.8
7,000 58.3 33.7 29.2 14.6 19.5 16.9 8.4 6.7
8,000 66.7 38.5 33.4 16.7 22.3 19.3 9.7 7.7
9,000 75.0 43.3 37.5 18.8 25.1 21.7 10.9 8.7
10,000 83.3 48.1 41.7 20.9 27.8 24.1 12.0 9.6
12,000 100.0 57.7 50.0 25.0 33.4 29.0 14.5 11.6
15,000 125.0 72.1 62.5 31.2 41.7 36.1 18.1 14.5
18,000 150.0 88.6 75.0 37.5 50.1 43.4 21.7 17.3
21,000 175.0 101.0 87.5 43.8 58.3 50.6 25.3 20.5
24,000 200.0 115.4 100.0 50.0 66.7 57.8 28.9 23.0
27,000 225.0 129.9 112.5 56.3 75.1 65.1 32.6 26.0
30,000 250.0 144.2 125.0 62.5 83.3 72.3 36.1 28.9
36,000 300.0 173.1 150.0 75.0 100.0 86.8 43.4 34.7

Controls are determined by finding the amperage per line and multiplying by 1.25 factor.

For single phase or two wire power supplies to heaters:

AMP Rating Per Pole*  = 
total capacity (watts)
line voltage

For three phase balanced power supplies (Delta or Wye connections) to heaters using a three-pole contactor.

AMP Rating Per Pole*  = 
total capacity (watts)
line voltage x 1.73

Contactor Sizing: *Amp rating per pole x1.25 = contactor rating.

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