Over-the-Range Microwave Installation

Over-the-range microwaves require a dedicated 120V, 20A circuit -- ideally with the outlet in the cabinet above so the power cord is hidden. This is the most common installation problem: the outlet doesn't exist or is in the wrong location. If replacing an existing OTR microwave: The circuit and outlet are already in place. Verify the new microwave uses the same cord type (most use a standard 15A or 20A plug). If installing OTR for the first time: Check the cabinet above for a power outlet. If there isn't one, an electrician needs to run a dedicated circuit before the installation day. This is not a DIY electrical step for most homeowners. Circuit load: Microwaves draw 1,500--1,800W (12.5--15A) when running. They should be on a dedicated circuit, not shared with other kitchen appliances. If the circuit is shared and trips frequently, that's the next problem to solve. Outlet location: Ideally, the outlet is in the back of the cabinet above, where the power cord drops straight up from the microwave. If the outlet is in the front of the cabinet, the cord needs to be routed to reach it without crimping.

If replacing an existing OTR microwave: 1. Unplug the old microwave from the outlet inside the cabinet above 2. Open the cabinet above and locate the two mounting bolts going through the cabinet floor -- these typically have large flat washers and are driven from inside the cabinet 3. One person holds the microwave from below (it's heavy), the other person removes the mounting bolts from the cabinet above 4. The microwave is also held by a wall mounting plate at the back -- once the top bolts are out, tilt the microwave out and up off the wall plate 5. Carefully lower the old microwave -- have a clear path to set it down Wall plate: The old microwave's wall mounting plate may or may not match the new one's mounting pattern. If the holes don't match, you'll need to fill and re-drill the wall for the new plate. Vent connection: Note how the old microwave's vent connects (or doesn't connect) to a duct -- the new microwave needs to match this configuration.

The wall mounting plate is the most critical part of the installation -- it must be level, at the correct height, and anchored into studs. Using the mounting template: 1. Tape the full-size paper template to the wall at the correct height (determined by your microwave's instructions -- typically measures from the cooking surface below) 2. Use a stud finder to locate studs in the mounting area 3. Mark stud locations on the template 4. Drill holes through the template into studs for the wall plate mounting screws 5. Remove the template and install the wall plate Stud vs. drywall anchor: Wall plate screws must hit studs wherever possible. One screw in a stud is worth three in drywall anchors for a dynamic load like a microwave. Use provided mounting hardware in studs; use appropriate toggle bolts only where studs are not available. Height: The bottom of the microwave must be at least 30 inches above the cooking surface (check your specific microwave's requirement -- they vary). Position the template to achieve this height. Level: Check the wall plate with a level before final tightening. A plate that's 1/4" off level results in a visibly crooked microwave.

Most microwaves require two holes in the bottom of the cabinet above: 1. A hole for the power cord (2" typical) 2. A hole for the exhaust duct if venting upward into the cabinet/exterior Using the template: The template also shows the required cabinet hole locations. Transfer these measurements and drill/cut from below (from inside the cabinet if possible) to avoid tearing the cabinet finish. Venting configuration -- this matters: - Rear vent: microwave exhausts out the back into an existing wall duct - Top vent (most common): microwave exhausts upward through the cabinet above and out through an external duct - Recirculating (no duct): air filters through a charcoal filter and recirculates into the kitchen -- lowest performance, no duct required The new microwave must be configured for the vent direction before mounting -- most OTR microwaves ship in recirculating mode but have a removable blower cap that must be rotated to configure for rear or top venting. Do this before mounting. It's extremely difficult to change after the unit is hung.

This step requires two people -- no exceptions. Hanging procedure: 1. Open the cabinet above before lifting -- you need access immediately after the microwave is in position 2. Feed the power cord up through the cabinet hole 3. Person 1 lifts and holds the microwave, hooking the back of the unit onto the wall mounting plate from below 4. Person 2 watches from the side to confirm the unit hooks onto the plate correctly 5. Once hooked and stable, Person 2 goes into the cabinet above and drives the long bolt(s) through the cabinet floor into the mounting bracket holes in the top of the microwave 6. Tighten these bolts fully -- they prevent the front of the microwave from tilting down 7. Plug in the power cord inside the cabinet Final checks: - Door opens and closes smoothly without hitting adjacent cabinet - Microwave is level (check with a level on the top/bottom surface) - Vent fan operates on all speeds - Light works - Run a test cycle: heat a cup of water for 30 seconds and confirm it heats - Check that the exhaust moves air in the configured direction