DAVIS Shelter Heaters - Manual (Page 4)

Page 4 Heater
Choosing Cable for the Heater
The heater comes with a 50-foot (15 m) length of 22 gauge, two twisted-pair
cable. When using this cable, the red and white wires are joined and used as
one wire and the two black wires are joined and used as one wire. You may use
22 gauge, two-twisted pair wire in this manner for cable lengths up to 120 feet
(36 m). If you want to use single pair cable, use the following table to deter-
mine the minimum wire size for the desired length of cable run.
If the heater cable is routed with a system signal cable, be aware that for cable
runs over 50 feet (15 m), you need to do at least one of the following to prevent
the heater cable’s voltage from interfering with sensor voltages.
✦ Use twisted pair for the heater cable or the signal cable.
✦ Use shielded cable for the heater cable or signal cable (shield must be
grounded).
✦ Keep the heater cable and the signal cable separated by several inches (at
least 8 cm) over most of the length of the cable run.
L ENGTH OF C ABLE R UN M INIMUM W IRE S IZE
Up to 60 feet (18 m) 22AWG (0.50 mm
2
)
60-100 feet (18-30 m) 20AWG (0.75 mm
2
)
100-160 feet (30-50 m) 18AWG (1.0 mm 2 )
160-250 feet (50-80 m) 16AWG (1.50 mm
2
)