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Minimum and Maximum Heating Cable Lengths:

An all-in-one reference

(Part of our collection of articles on Everything You Need to Know about Heating Cable)

The maximum length of heating cable that you can run with the confidence that you won't blow a fuse depends on several things. Specifically, you need to know:

  • What kind of cable you have: Self-regulating or constant-wattage? What supply voltage? And in some cases, what wire gauge? If you have the full model number, you're set to go.
  • If it's self-regulating, what will be the minimum temperature of the cable when it's started up? (Self-regulating cables draw more power the colder they are, so a cable that runs fine at 50°F might blow your circuit breaker if you start it up at 0°F.)
  • How many amps is your circuit breaker built for?

The most surefire way of making sure you're running a safe length of cable is to check the specific spec sheet for the kind of cable you have; if you ever need them, these spec sheets are available on the ordering pages for each variety of heating cable we sell. However, we've also put together this page as an easy, all-in-one reference for minimum and maximum circuit lengths. Just find the table below that corresponds to the kind of heater you have.

Quick jump to: Self-regulating cable (Low-temperature, Mid-temperature, Freezstop 12/24-volt), Constant-wattage

SELF-REGULATING HEATING CABLE
Series Circuit
breaker
size (amps) 		Minimum
circuit
length (ft) 		Maximum circuit length (ft), if
start-up temperature is...
50°F
(10°C) 		0°F
(–18°C) 		–20°F
(–29°C)
Low-temperature styles
SLCAB3120:
3 W/ft
120 VAC 		15 1 300 200 180
20 — 270 230
30 — 330 330
SLCAB3240:
3 W/ft
240 VAC 		15 1 660 410 360
20 — 560 480
30 — 660 660
SLCAB5120:
5 W/ft
120 VAC 		15 1 230 150 130
20 270 200 175
30 — 270 260
SLCAB5240:
5 W/ft
240 VAC 		15 1 460 300 260
20 540 400 345
30 — 540 520
SLCAB8120:
8 W/ft
120 VAC 		15 1 150 95 85
20 200 125 100
30 210 190 170
40 — 210 210
SLCAB8240:
8 W/ft
240 VAC 		15 1 295 195 170
20 390 250 225
30 420 375 340
40 — 420 420
SLCAB10120:
10 W/ft
120 VAC 		15 1 115 70 60
20 150 95 85
30 180 145 120
40 — 180 165
SLCAB10240:
10 W/ft
240 VAC 		15 1 230 150 130
20 305 200 175
30 360 300 260
40 — 360 360
Mid-temperature styles
SLMCAB5120:
5 W/ft
120 VAC 		15 1 150 135 130
20 200 180 170
30 240 220 210
SLMCAB5240:
5 W/ft
240 VAC 		15 1 250 230 220
20 330 305 295
30 480 440 120
SLMCAB10120:
5 W/ft
120 VAC 		15 1 30 85 80
20 120 110 105
30 180 165 160
SLMCAB10240:
10 W/ft
240 VAC 		15 1 140 130 125
20 190 175 170
30 280 260 250
SLMCAB15120:
15 W/ft
120 VAC 		15 1 70 65 60
20 90 85 20
30 130 125 120
SLMCAB15240:
15 W/ft
240 VAC 		15 1 100 95 90
20 135 125 120
30 200 185 180

Low-voltage (Freezstop)
Series Circuit
breaker
size (amps) 		Minimum
circuit
length (ft) 		Maximum circuit length (ft), if
start-up temperature is...
41°F
(5°C) 		32°F
(–0°C) 		–4°F
(–20°C) 		–40°F
(–40°C)
12FLV1:
3.6 W/ft
11/12 VAC 		6 1 13 13 9.5 6.5
10 23 19 16 13
16 33 33 26 19
12FLV2:
3.6 W/ft
22/24 VAC 		6 1 26 26 19 13
10 46 39 33 26
16 65 65 52 39
17FLV1:
5.2 W/ft
11/12 VAC 		6 1 9.5 9.5 9.5 6.5
10 16 16 13 13
16 26 26 23 19
17FLV2:
5.2 W/ft
22/24 VAC 		6 1 19 19 19 13
10 33 33 26 26
16 52 52 46 39


CONSTANT-WATTAGE CABLES
Minimum,* maximum circuit length, in feet
*This is found by doubling the circuit module length. When cutting heating cable, we use a minimum length of double the circuit module length to ensure that the cable contains at least one full module.
General-purpose
(note: the model number suffixes -B and -SS can be ignored.)
120 VAC 208 VAC 240 VAC 277 VAC 480 VAC
3 W/ft FECAB3120:
4.0, 360		 FECAB3208:
8.0, 625		 FECAB3240:
8.0, 720		 N/A FECAB3480:
16.0, 1440
5 W/ft FECAB5120:
4.0, 275		 FECAB5208:
8.0, 477		 FECAB5240:
8.0, 550		 N/A FECAB5480:
12.0, 1100
8 W/ft FECAB8120:
4.0, 220		 FECAB8208:
8.0, 381		 FECAB8240:
8.0, 440		 FECAB8277:
8.0, 508		 FECAB8480:
12.0, 880
12 W/ft FECAB12120:
4.0, 180		 FECAB12208:
12.0, 312		 FECAB12240:
4.0, 360		 FECAB12277:
8.0, 416		 FECAB12480:
8.0, 720
Harsh-environment high-temperature
4 W/ft KECAB4120:
8.0, 310		 KECAB4208:
8.0, 537		 KECAB4240:
8.0, 620		 KECAB4277:
8.0, 716		 KECAB4480:
16.0, 1240
8 W/ft KECAB8120:
8.0, 220		 KECAB8208:
8.0, 381		 KECAB8240:
8.0, 440		 KECAB8277:
8.0, 508		 KECAB8480:
12.0, 880
12 W/ft KECAB12120:
4.0, 180		 KECAB12208:
12.0, 312		 KECAB12240:
8.0, 360		 KECAB12277:
8.0, 416		 KECAB12480:
12.0, 720
Fiberglass high-temperature
(note bus wire size, in American wire gauge)
4 W/ft,
16 AWG		 KMCAB412016:
8.0, 190		 KMCAB420816:
8.0, 329		 KMCAB424016:
8.0, 380		 KMCAB427716:
8.0, 439		 KMCAB448016:
16.0, 760
4 W/ft,
12 AWG		 KMCAB412012:
8.0, 310		 KMCAB420812:
8.0, 537		 KMCAB424012:
8.0, 620		 KMCAB427712:
8.0, 716		 KMCAB448012:
16.0, 1240
8 W/ft,
16 AWG		 KMCAB812016:
8.0, 112		 KMCAB820816:
8.0, 194		 KMCAB824016:
8.0, 224		 KMCAB827716:
8.0, 259		 KMCAB848016:
12.0, 448
8 W/ft,
12 AWG		 KMCAB812012:
8.0, 220		 KMCAB820812:
8.0, 381		 KMCAB824012:
8.0, 440		 KMCAB827712:
8.0, 508		 KMCAB848012:
12.0, 880
12 W/ft,
12 AWG		 KMCAB1212012:
8.0, 180		 KMCAB1220812:
12.0, 312		 KMCAB1224012:
8.0, 360		 KMCAB1227712:
8.0, 416		 KMCAB1248012:
8.0, 720
Polyimide high-temperature
4 W/ft KKCAB4120:
8.0, 310		 KKCAB4208:
8.0, 537		 KKCAB4240:
8.0, 620		 KKCAB4277:
8.0, 716		 KKCAB4480:
16.0, 1240
8 W/ft KKCAB8120:
4.0, 220		 KKCAB8208:
8.0, 381		 KKCAB8240:
8.0, 440		 KKCAB8277:
8.0, 508		 KKCAB8480:
12.0, 880
12 W/ft KKCAB12120:
4.0, 180		 KKCAB12208:
8.0, 312		 KKCAB12240:
8.0, 360		 KKCAB12277:
8.0, 416		 KKCAB12480:
14.0, 720
18 W/ft KKCAB18120:
3.5, 120		 KKCAB18208:
6.0, 208		 KKCAB18240:
7.0, 240		 KKCAB18277:
8.0, 277		 KKCAB18480:
11.0, 480