How Do I Determine My Supply Voltage?
Please note: Testing with a voltmeter requires the circuit panel or fuse box to remain on. If you’re unfamiliar or uncomfortable with electrical wiring, please contact a qualified technician or licensed electrician.
Your circuit breaker panel has 2 different 120 Volt phases staggered. Between each breaker you need to make sure you have 240 Volt for a 240 Volt heater. 240 VOLT AND 120 VOLT HEATERS ARE NOT INTERCHANGABLE! To test your supply voltage perform these simple tests using a test light or voltmeter.
Test 1 – For 120 and 240 Volt Heat Power Supply
Touch black wire and ground with test instrument.
Result: Test light will illuminate if voltage is 120 or voltmeter will read 120 Volts. This is the correct power supply for a 120 Volt heater.
Test 2 – For 240 Volt Heat Power Supply
Touch white wire to ground with test instrument. Repeat test one above.
Result: Test light will illuminate if voltage is 120 or voltmeter will read 120 Volts. This is the correct power supply for a 120 Volt heater.
Test 3 – To Confirm 240 Volt Power Supply
Touch black wire and white wire with test instrument.
Result: Test light should illuminate bright and voltmeter should read 240 Volt. If heater is 120 Volt the meter will read 120 Volt.
If test light does not illuminate in test 3, or voltmeter reads 0 Volts, the same phase has been wired to the heater and you have 120 Volt from the same phase of the circuit panel.
