How to Wire a Microwave Oven

Introduction

Wiring a microwave oven may seem intimidating, but with proper precautions and by following some basic steps, I was able to successfully wire my microwave oven. A microwave oven requires both 120V power and low voltage control wiring to operate properly and safely.

Safety Precautions

Before wiring a microwave oven, it's crucial to follow all safety precautions:

Always disconnect the power supply before working on any electrical wiring. This is extremely important to avoid electrocution. Use the circuit breaker to cut off power.
Use proper protective equipment like insulated gloves and eyewear when handling exposed wires. This protects from shocks and debris getting in eyes.
Follow all electrical codes and regulations. Improper wiring can lead to fires or other hazards. Review your local regulations.
Inspect the microwave cavity for damage before wiring. Cracks or holes can allow radiation to leak. The oven should not be used if damaged.
Ensure proper grounding. Microwave ovens require a grounded 120V power connection for safety. Improper grounding is dangerous.
Hire an electrician if uncomfortable with any part of the wiring process. Microwave wiring requires knowledge of electrical systems.

Wiring the Power Supply

The power supply provides 120V AC power to the microwave oven. Follow these steps to connect it properly:

Step 1: Run Power Cable to Electrical Box

Use 3-wire NM cable with ground wire. 12 gauge wire is recommended.
Run cable from oven location to nearby electrical box. Follow local codes.
Leave about 6 inches of extra cable at oven location to make connections.

Step 2: Connect Power Cable to Electrical Box

Connect cable hot wire (black) to hot supply wire (typically also black).
Connect cable neutral wire (white) to neutral supply wire (typically white).
Connect ground wire (green or bare) to grounding screw or bus bar in the box.

Step 3: Connect Power Cable to Microwave Oven

Remove outer cover panel of microwave to access connection points.
Connect black cable wire to black "L" terminal on oven.
Connect white cable wire to white "N" terminal.
Connect ground wire to green grounding screw in oven.

Wiring the Low Voltage Controls

The control wiring allows the microwave's control panel to communicate with the high voltage components. It typically uses low voltage DC.

Step 1: Identify Control Board Wiring Points

The control board has multiple low voltage terminals.
Locate wiring diagram usually printed on back or inside of oven.
Identify terminals for door switches, control panel, fan motor, etc.

Step 2: Run Control Wires

Use gauge specified in wiring diagram, typically 18-22 gauge.
Run wires from control board to each component needing connection.
Leave 6 inches extra at each end to make connections.

Step 3: Connect Wires

Refer to wiring diagram for each wire's terminal.
Attach door switch wires to proper terminals on control board.
Connect control panel wires, light wires, fan motor wires, etc.
Follow diagram exactly to avoid functionality issues.

Testing and Use

After all wiring is complete, test operation thoroughly:

Restore power and check for sparks, smoke, or odor - if found, disconnect power immediately.
Ensure oven light turns on when door is open.
Test that fan runs when oven is on.
Verify door switches disable cooking when opened.
Heat a cup of water and ensure it gets hot (starts with small test amount).

If everything checks out, the microwave can now be permanently installed and used for cooking. Always refer to the owner's manual for proper usage and safety. Proper wiring is essential for safe operation.

Conclusion

While it requires attention to safety, the process of wiring a microwave oven is straightforward when done carefully. The key steps are running and securing the power supply cable, connecting low voltage control wires per the wiring diagram, and thoroughly testing operation before regular use. With the proper precautions and connections in place, a wired microwave can provide safe, reliable performance.