Electrical Insulation Testing - Rheem Everhot 2A1050M7 Service Instructions Manual

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 this
procedure to reduce the risk of electric shock.
To check insulation resistance of the water heater Neutral Circuit (reading not to be
below 1 mega-ohm).
1. Isolate the power supply to the water heater by removing fuse or switching off
circuit breaker. Confirm with a multi-meter across the Active(s) and Neutral
wires at the terminal block that voltage is not present (refer to "Test 1" on page
21).
2. Once satisfied, disconnect the power supply active and neutral wires from the terminal
block. Note: If model is a twin element model, mark and disconnect both active wires
(marked 'A1' and 'A2').
3. Connect megger leads to the neutral of the water heater wiring and earth.
4. Operate megger on 500 VDC setting. A reading above 1 mega-ohm should be
obtained.
5. If a reading below 1 mega-ohm is obtained, all component parts will need to be
individually tested to locate the fault (refer to "fault finding chart 1.1" on page 15).
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 on 500 VDC setting. A reading above 1 mega-ohm should be
obtained.
8. If a reading below 1 mega-ohm is obtained, all component parts will need to be
individually tested to locate the fault (refer to "fault finding chart 1.1" on page 15).
To check "Continuity" of the water heater electrical circuit.
9. Set megger to resistance scale or multimeter to x1 resistance scale and measure
between the active and neutral wires on the water heater.
10. If a reading of less than 10 ohms or greater than 35 ohms is obtained, all electrical
component parts will need to be individually tested to locate the fault (refer to "Test 5"
on page 22).
11. Reconnect power supply active cable to 'A' terminal and neutral cable to 'N' terminal at
heater terminal block.
12. Replace fuse or reset circuit breaker. Note: If continuing with diagnosis procedures
do not replace fuse or reset circuit breaker.
TM074: Stainless Steel Electric Water Heater Service Instructions
REV AB Issued: 07/16
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