TM 10-3510-226-23
0025 00
TEST-CONTINUED
Test the Electric Box Heater
WARNING
This equipment operates at high voltages. Use extreme caution, observe all warnings,
and follow all safety procedures. Failure to observe safety precautions may result in
injury or death to personnel.
WARNING
Do not attempt to verify operation of the heater by touch. Failure to observe safety
precautions may result in burn injuries to personnel.
NOTE
The electric box heater is thermostatically controlled, and will not come on until cooled
below 40oF. Indications that the heater may be inoperative include the presence of
condensation within the PLC enclosure.
1. Disconnect power at the main circuit breaker.
2. Open PLC enclosure.
3. Tag and disconnect wiring from heater (Figure 26, Item 52). It may be necessary to cut and strip the
heater wiring to test the heater.
NOTE
The electric box heater is thermostatically controlled, and will not come on until cooled
below 40oF. It may be necessary to remove the heater and test it in a refrigerated
environment.
4. Use an ohmmeter to test for 140 to 150 ohms resistance.
5. Connect wiring to heater (Figure 26, Item 52) as tagged.
6. Close PLC enclosure, then connect power and operate the PLC.
7. Monitor for normal operation.
0025 00-32
