TM012 Rheem Electric Water Heaters Service Instructions REV: B
Date of Issue: 03/06
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25
Fault Finding Chart 7
7
Is the
reading below 1
mega-ohm?
Electrical Insulation Test
Replace element
YES
Is the
reading below 1
mega-ohm?
Replace thermostat
Rewire fuse or reset circuit breaker
if necessary
Rewire fuse or reset circuit breaker
if necessary
YES
Check for pinched or damaged
wiring touching the heater chassis
NO
Disconnect the wires to the
element from the thermostat and
megger between each element
wire and earth
Disconnect remaining wires from
the thermostat and megger
between each thermostat terminal
and earth
NO
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.
Test 2 - 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.
Test 3 - 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 above.
Test 4 - 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 15 for indicative
resistances.
11. Reconnect the active conductor to the ‘A’ terminal and neutral conductor to ‘N’ terminal
at heater terminal block.
12. Replace fuse.
Note:
If continuing with flow chart 1.1 or 2.1of diagnostic
procedure do not replace fuse.
