King Electric SR self-reg, cut to length - Manual (Page 4)

Model Volts Watt/ft
Maximum
Single Run Length
SR123 120V 3 w/ft 325 ft. (99M)
SR243 240V 3 w/ft 650 ft. (198M)
SR125 120V 5 w/ft 270 ft. (82M)
SR245 240V 5 w/ft 540 ft. (165M)
SR128 120V 8 w/ft 210 ft. (64M)
SR248 240V 8 w/ft 420 ft. (128M)
SR1210 120V 10 w/ft 180 ft. (55M)
SR2410 240V 10 w/ft 360 ft. (110M)
Model 240V 208 V 220 V 277V
SR243 3.0 2.5 2.7 3.4
SR245 5.0 4.3 4.6 5.5
SR248 8.0 7.0 7.44 8.6
SR2410 10.0 9.0 9.4 10.5
Volts
Start up
Temp.
Circuit
Breaker*
SR123
3w/ft.
SR125
5w/ft.
SR128
8w/ft.
SR1210
10w/ft.
120 V
50ºF (10ºC)
15 Amp 325 ft. (99M) 225 ft. (69M) 145 ft. (44M) 115 ft. (35M)
20 Amp 435 ft. (133M) 270 ft. (82M) 195 ft. (59M) 150 ft. (46M)
30 Amp 655 ft. (200M) 450 ft. (138M) 290 ft. (88M) 230 ft. (70M)
40 Amp 875 ft. (267M) 540 ft. (164M) 390 ft. (188M) 300 ft. (92M)
0ºF
(-18ºC)
15 Amp 230 ft. (70M) 155 ft. (47M) 100 ft. (30M) 85 ft. (26M)
20 Amp 305 ft. (93M) 205 ft. (72M) 130 ft. (40M) 110 ft. (34M)
30 Amp 460 ft. (140M) 310 ft. (94M) 195 ft. (59M) 155 ft. (47M)
40 Amp 615 ft. (188M) 410 ft. (144M) 260 ft. (80M) 220 ft. (68M)
-20ºF
(-29ºC)
15 Amp 205 ft. (63M) 135 ft. (41M) 90 ft. (27M) 75 ft. (23M)
20 Amp 275 ft. (84M) 180 ft. (55M) 115 ft (35M) 100 ft. (30M)
30 Amp 415 ft. (127M) 270 ft. (82M) 175 ft. (53M) 145 ft. (44M)
40 Amp 555 ft. (169M) 360 ft. (110M) 230 ft. (70M) 200 ft. (60M)
Volts
Start up
Temp.
Circuit
Breaker*
SR243
3w/ft.
SR245
5w/ft.
SR248
8w/ft.
SR2410
10w/ft.
240 V
50ºF (10ºC)
15 Amp 650 ft. (198M) 460 ft. (140M) 295 ft. (90M) 230 ft. (70M)
20 Amp 865 ft. (264M) 540 ft. (165M) 390 ft. (119M) 305 ft. (93M)
30 Amp 1300 ft. (396M) 920 ft. (280M) 590 ft. (180M) 460 ft. (140M)
40 Amp 1725 ft. (529M) 1080 ft. (330M) 780 ft. (238M) 610 ft. (186M)
0ºF
(-18ºC)
15 Amp 460 ft. (140M) 310 ft. (94M) 200 ft. (61M) 165 ft. (50M)
20 Amp 615 ft. (188M) 415 ft. (127M) 265 ft. (81M) 220 ft. (67M)
30 Amp 925 ft. (282M) 620 ft. (189M) 395 ft. (120M) 325 ft. (99M)
40 Amp 1235 ft. (377M) 830 ft. (254M) 420 ft. (128M) 440 ft. (134M)
-20ºF
(-29ºC)
15 Amp 410 ft. (125M) 275 ft. (84M) 175 ft. (53M) 150 ft. (46M)
20 Amp 545 ft. (166M) 379 ft. (113M) 235 ft (72M) 195 ft. (59M)
30 Amp 820 ft. (250M) 540 ft. (165M) 350 ft. (107M) 290 ft. (83M)
40 Amp 1095 ft. (334M) 758 ft. (226M) 420 ft. (128M) 390 ft. (118M)
Table 3: Maximum Single Cable Length
Table 4: Wattage Adjustment (W/Ft)
The maximum length of a single cable run is noted in Table 3
and cannot be exceeded. If the application requires a longer
cable run, then multiple cables and additional power circuits
must be used.
When using 240 volt SR cable on 208, 220 or 277 volt
applications, the power output (wattage) must be adjusted.
Refer to Table 4 for the adjusted watts/ft of the cable when
operated at a voltage other than 240 volt.
Circuit protection depends on the length of cable required
and the start-up temperature since the cable will draw more
power (wattage) when cold. Multiple cables can be run from
a single power circuit up to a maximum combined length as
noted in Table 5. Larger amperage circuits breakers can
handle longer combined cable lengths, but the maximum
length for a single cable run does not change. The NEC
requires the use of ground fault protection breakers for
heating cable.
NOTE: 240 volt cable lengths in Table 5 are also good for
208, 220, and 277 volt.
Table 5: Circuit Protection Per Combined Cable Length for Pipe Freeze Protection
Circuit Breaker Protection and Cable Length Design for Pipe Freeze Protection
Rev 11.04.12 www.king-electric.com 4