Quck answer
To test a 240-volt circuit, follow these steps:
1. Turn off the power to the circuit at the main electrical panel.
2. Use a voltage tester to ensure that there is no electricity flowing through the circuit.
3. Remove the cover plate from the outlet or switch you want to test.
4. Use a multimeter set to AC voltage to test the circuit’s voltage. Place one probe on the hot wire and the other probe on the ground wire or neutral wire.
5. If the reading on the multimeter is around 240 volts, the circuit is functioning correctly.
6. Replace the cover plate and restore power to the circuit.
The electricity that flows through your circuit breaker is rated at 120 volts, but it is commonly referred to as 110 volts, just as electricity at 240 volts is typically called 220 volts. A 240-volt circuit is created by combining two 120-volt circuits and a ground wire. This type of circuit is usually installed to provide power for heavy-duty appliances like air conditioners, clothes dryers, stoves, ovens, and water heaters. By learning how to test your 240-volt circuit, you can effectively diagnose any issues with your electrical system.
Step 1
Take a look at your 240-volt wall outlet and familiarize yourself with its configuration. A typical 240-volt wall outlet has three openings: two identical slots slanted at a 45-degree angle (sometimes vertical), and one middle slot positioned lower than the two vertical slots. Each of the two vertical slots carries 120 volts, while the third or middle slot is the ground connection.
Step 2
Set your multimeter’s dial to a range of 240 volts AC, and attach the black and red test probes to the multimeter. Remember to never touch the metal tip of the probes while they are in use to avoid the risk of electric shock.
Step 3
Insert one test probe’s metal end into any of the slanted 120-volt slots, and insert the other test probe’s metal end into the next identical slot. Take note of the reading displayed on your multimeter. The two 120-volt circuits connected to your multimeter are generating a total current of 240 volts. Your multimeter should show a reading of approximately 240 volts; if it doesn’t, there may be a problem with one or both circuits.
Step 4
Adjust the dial on your multimeter to 120 volts. Place the red probe’s metal tip into any of the slanted 120-volt slots, and insert the black probe’s metal tip into the middle (ground) slot. Your multimeter should display a reading of approximately 120 volts AC. If it doesn’t, that circuit is likely defective. Repeat the same procedure on the other 120-volt slot to determine if that circuit is functioning properly.
