How to Wire a 240Vt Circuit From a 100 Amp Service Panel

Power panel

Different homes require different amounts of power. Most early small homes used a 100-amp service panel. This panel usually had 24 slots available for various breakers. Circuits that require 240 volts must use two breaker slots. If a home with a 100-amp service panel needs two 240-volt circuits, then those two circuits will take up four slots in the power panel. In today's high tech world, 100-amp service feeds are becoming more of a rare occurrence.

Things You'll Need

• Wire strippers
• Wire cutters
• Romex wire 10-3 or 8-3
• Voltage tester
• Screwdriver
• Hammer

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Instructions

1. Look inside the main power panel, and verify if there are two adjacent breaker slots available. A 240V service will require a double breaker.

2. Go to the main power panel and shut off the main 100-amp power breaker. Unscrew the screws which hold the power panel breaker cover in place, and remove the breaker cover.

3. Strip half of an inch of insulation off the ends of the 10-3 Romex wire. Run the wire through one of the round knockouts on the power panel and up into the box. Do not tough any of the wires on the feed side of the main breaker. They are live wires.

4. Connect the black wire to the first terminal on the new double-pole breaker. Connect the red wire to the second terminal of the double-pole breaker. Take the ground wire and the neutral wire and connect them to the common bar inside the power panel.

5. Plug the double-pole breaker into the next set of breaker slots. Make sure it is switched to the off position. Fish the other end of the Romex wire through the wall or through the conduit to the termination location.

6. Strip half of an inch of insulation off the ends of the 10-3 Romex wire, and follow the installation instructions for the type of receptacle or other equipment being installed.

7. Turn the power back on and test the circuit operation.

References

• Nojolt.com: Installing 220 / 240 Volt Electrical Circuits