DAVIS Rain Collector Heater - Manual (Page 3)

Installing the Rain Collector Heater
3
Choosing Cable for the Rain Collector Heater
The rain collector heater comes with a 50-foot (15
m) length of 22 gauge
cable. You may use 22 gauge, two-twisted pair wire for cable lengths up to 120
feet (36
m). If you want to use single pair cable, use the following table to
determine the minimum wire size for the desired length of cable run.
Length of Cable Run Minimum Wire Size
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
)
If the heater cable is routed with any signal cable (i.e. any cable running from
a sensor, junction box or SIM), be aware that for cable runs over 50 feet
(15
m) the heater cable’s voltage may interfere with sensor voltages in the
signal. To prevent this interference, do at least one of the following:
• 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 over
most of the length of the cable run.
Installing the Rain Collector Heater
The instructions below will take you step-by-step through the procedure
required to install the rain collector heater. Make sure the wall transformer is
unplugged until you are instructed to plug it in.
Attaching the Heater to the Rain Collector
1. Remove the rain collector’s cone from the base and, if necessary, remove
the mounting screws from the base of the rain collector.
2. If screw holes for the rain collector heater are not already present in the
base, position the heater as shown on the next page (with the terminal block
facing away from the bucket) and mark the location of the screw holes on
the heater assembly.