Specifications

TM013 Vulcan Electric Service Instructions REV: D
D.O.I.: 05/09
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23
Electrical Insulation Testing
There are three basic test procedures that should be carried out when the operation and
function of a water heater‟s electrical system is in doubt.
Personal Protective Equipment should be worn when conducting step 1 of
this procedure to reduce the risk of electric shock. Refer to Rheem safety
procedure on electrical testing
To check insulation resistance of the water heater Neutral Circuit (reading not to be
below 1 mega-ohm).
1. Isolate power to the water heater by removing fuse. Confirm with multi-meter
across Active and Neutral at the terminal block that voltage is not present.
2. Once satisfied, disconnect the active and neutral wires from the terminal block.
3. Connect megger leads to the neutral of the water heater wiring and earth.
4. Operate megger. A reading above 1 mega-ohm should be obtained.
5. If a reading below 1 mega-ohm is indicated, all component parts will need to be
individually tested to locate the fault. Refer to flow diagram 7 above.
To check insulation resistance of the water heater Active Circuit (reading not to be
below 1 mega-ohm).
6. Connect megger leads to the active of the water heater wiring and earth.
7. Operate megger. A reading above 1 mega-ohm should be obtained.
8. If a reading below 1 mega-ohm is indicated, all component parts will need to be
individually tested to locate the fault. Refer to flow diagram 7.
To check “Continuity” of water heater electrical circuit.
9. Set megger to resistance scale or multimeter to x1 resistance scale.
10. If a reading greater than 50 ohms is indicated, all electrical component parts will need
to be individually tested to locate the fault. Refer to test 8, page 26 for indicative
resistances.
11. Reconnect active cable to ‟A‟ terminal and neutral cable to „N‟ terminal at heater
terminal block.
12. Replace fuse. Note: If continuing with diagnosis procedures do not replace fuse.
Disconnect the element wires from
the thermostat and megger
between each wire and earth.
NO
Replace Element
Rewire fuse or reset circuit breaker if
necessary.
Electrical insulation diagnostic
Is the reading below 1MΩ? YES
Disconnect the remaining wires
from the thermostat and megger
between each thermostat terminal
and earth.
Is the reading below 1MΩ?
Replace Thermostat.
Rewire fuse or reset circuit breaker if
necessary.
YES
Check for pinched or damaged wiring
touching the heater chassis.
NO