Cold Weather Catalog - Chromalox Precision Heat and Control

Heating CableSRFSelf-Regulating FreezeProtection (cont’d.)Thermal Output Ratings on Insulated Metal Pipe 11413121110Heat Output (W/Ft.)9876543218 W/Ft.Cable Output vs.Temperature5 W/Ft.3 W/Ft.0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150Pipe Temperature (°F)Note 1 — Thermal output is determined per IEEE 515-2004 Standard for testing, designinstallation, and maintenance of electrical resistance heat tracing section 4.1.11Method C.Thermal Output Ratings on Plastic Pipe with Aluminum TapeHeat Output (W/Ft.)987654321SRF3SRF5SRF8Cable Output vs.Temperature0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150Pipe Temperature (°F)Output Wattage at Alternate Voltages (W/Ft.)Model 208V% ChangeIn Output 220V% ChangeIn Output 277V% ChangeIn OutputSRF 3 2.4 -20 2.6 -13 3.4 +15SRF 5 4.1 -18 4.5 -10 5.6 +13SRF 8 6.88 -14 7.28 -9 8.96 +12Circuit Breaker Selection (Max. Circuit Lengths in Ft.)Cable40°F Start-Up (Ft.) 0°F Start-Up (Ft.)Rating 20A 30A 40A 20A 30A 40ASRF 3-1C 350 360 NR 270 360 NRSRF 3-2C 660 NR NR 555 660 NRSRF 5-1C 230 270 NR 180 270 NRSRF 5-2C 450 540 NR 360 540 NRSRF 8-1C 180 215 NR 145 215 NRSRF 8-2C 330 420 420 265 395 420NR = Not Required. Maximum circuit length has been reached in a smaller breaker size.Note — Thermal magnetic circuit breakers are recommended since magnetic circuitbreakers could "nuisance trip" at low temperature.108