TM039 Rheem Water Star Service Instructions REV: A
Date of Issue: 02/09
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18
Fault Finding Chart 6
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.
Test 2 - To check insulation resistance of the water heater Neutral Circuit (reading
not to be below 1
MΩ).
1. Switch off power at GPO and unplug power cord from GPO (unplug continuous
flow water heater).
2. Connect megger leads to the neutral of the water heater wiring and earth.
3. Operate megger. A reading above 1
MΩ should be obtained.
4. If a reading below 1
MΩ is indicated, all component parts will need to be individually
tested to locate the fault. Refer to flow diagram chart 6, above.
Test 3 - To check insulation resistance of the water heater Active Circuit (reading
not to be below 1
MΩ).
1. Connect megger leads to the active of the water heater wiring and earth.
2. Operate megger. A reading above 1
MΩ should be obtained.
3. If a reading below 1
MΩ is indicated, all component parts will need to be individually
tested to locate the fault. Refer to flow diagram chart 6, above.
Test 4 -
To check “Continuity” of water heater electrical circuit.
1. Set megger to resistance scale or multimeter to x1 resistance scale.
2. Measure between the active and the neutral of the water heater. If a reading between
68-79 ohms is not indicated, all electrical component parts will need to be individually
tested to locate the fault.
3. Reconnect the power cord. Note:
If continuing with diagnostic procedure flow
chart 1.1 do not reconnect the power cord.
6
Disconnect the remaining wires
from the thermostat and megger
between each thermostat terminal
and earth.
Check for:
Faulty 3 pin outlet socket
Pinched or damaged wiring
touching the heater chassis
Replace thermostat
Is the reading below 1
Megaohm?
Is the reading below 1
Megaohm?
YES
Disconnect the wires to the
element from the thermostat and
megger between each element
wire and earth.
Replace element
YES
NO
NO
Rewire fuse or reset circuit
breaker, if necessary
Rewire fuse or reset circuit
breaker, if necessary
Electrical Insulation Test
NOTE: Unplug continuous flow water heater
prior to commencing insulation testing
