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CLT Circuit Breaker Selection
|
Nominal
Watts/Ft.
|
Startup
Temp.
°F |
Maximum
Length (in feet) vs. Circuit Breaker Size |
| 120 Volt
Heaters |
|
240 Volt
Heaters |
| 15A |
20A |
30A |
|
15A |
20A |
30A |
| 3 |
50 |
221 |
|
|
|
533 |
|
|
| 0 |
208 |
221 |
|
|
416 |
533 |
|
| -20 |
187 |
221 |
|
|
374 |
499 |
533 |
| 5 |
50 |
178 |
|
|
|
413 |
458 |
|
| 0 |
150 |
178 |
|
|
299 |
399 |
458 |
| -20 |
135 |
178 |
|
|
269 |
359 |
458 |
| 8 |
50 |
142 |
|
|
|
289 |
347 |
|
| 0 |
105 |
140 |
142 |
|
210 |
280 |
347 |
| -20 |
95 |
127 |
142 |
|
190 |
253 |
347 |
Notes:
-
Circuit breakers are sized per article 427-4 of the
N.E.C. The heater lengths shown above represent a current
of no more than 80% of the breaker's rated size.
-
When using 240 volt product at 208, 220 or 277 volts,
multiply the lengths shown above by the
"length" adjustment factor shown in the Voltage Adjustment Table.
-
When using 2 or more heater cables of different wattage
ratings in parallel on a single circuit breaker, divide
15 amps by the maximum footage shown in the 15A column
above to arrive at an "amps per foot" figure
for each cable. You can then calculate circuit breaker
sizes for these combination loads. These "amps per
foot" factors include the N.E.C. sizing factor in
Article 427-4.
-
Article 427-22 of the N.E.C.
requires ground-fault equipment protection for each branch circuit
supplying electric heating equipment. Exceptions to this requirement can
be found in the N.E.C.
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