How to Wire a 120/240-Volt Receptacle for an Electric Range

How to Wire a 120/240-Volt Receptacles for an Electric Range

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Electric cooking ranges (stoves) have special wiring needs because they require a 120/240-volt circuit and receptacle. While gas stoves also are plugged in to provide power to operate the timers, vent fans, and other accessories, these stoves use simple 120-volt household circuits. An electric range, on the other hand, makes use of 120-volt current for the same purposes, but it also uses 240-volt current to heat the stovetop heating elements and oven heating coils. Hence, it requires a 120/240 volt receptacle and circuit that provides an independent neutral wire that provides a return path for the 120-volt portion of the circuit. In this respect, an electric range is much like an electric clothes dryer, which also uses a 120/240-volt receptacle. In the case of the clothes dryer, the timer and tumbler chamber are powered by a 120-volt current, but the heating unit of the dryer is powered by a 240-volt current.

Freestanding vs. Drop-In Ranges

An outlet receptacle is usually required only for free-standing upright ranges. Drop-in cooktops or wall ovens are usually hardwired, with the circuit wiring connected directly into the appliance connection panel, without the benefit of a plug-in cord and receptacle. The following instructions, then, are normally used only for freestanding upright range/oven units.

Circuits for Electric Ranges

Before wiring the end receptacle where you will plug in the range, there are some preliminaries. First, a 240-volt circuit of the proper amperage rating will need to be run from the main circuit breaker panel to the location where you want the receptacle. While some DIYers have the necessary skills to run new electrical circuits, for most people this is a job for a professional electrician, since such work can be quite dangerous if you don't know what you are doing. It involves installing a new 240-volt circuit breaker and routing the electrical cable through walls to the location where the range outlet will be located.

The electrical circuit that powers an electric range must be of sufficient amperage to supply the necessary power to the range. The power demand of ranges varies depending on the rating of the appliance, but in most cases, a 50-amp 240-volt circuit is required, wired with #6-gauge wire. Smaller ranges may require a 40-amp circuit, wired with #8-gauge wire. Either way, the circuit is wired with 3-wire cable, including white, black, and red wires, plus a bare copper ground wire.

The NEC has different rules for different types of ranges. Drop-in ranges are usually hard-wired, and the circuit conductors must be sized for the wattage of the nameplate rating of the appliance. Circuits for plug-in freestanding ranges can actually be lower than the nameplate rating. If the rating is 12,000 watts or less, the circuit can be designed for 8,000 watts. This means you could supply your new receptacle with #8 AWG cable and a 40-amp breaker, rather than #6 cable and a 50-amp breaker. The NEC makes this allowance because the nameplate rating is based on the oven and burners all being on HIGH at the same time, which doesn’t happen very often. But if you’ve ever hosted a big dinner, you know that firing everything at once, and for long periods, sometimes does happen. Therefore, it’s a common best practice to wire a range circuit with a 50-amp breaker and #6-gauge cable.

Wiring the Power Cord on the Range

Another preliminary is connecting the appliance power cord to the range. Most ranges do not come with the power cord attached; this is a component you will need to buy separately and connect yourself. Unlike the installation of the circuit itself, connecting the power cord is relatively easy work so most DIYers can do it themselves. While circuit size may vary, what can’t vary is the power cord and receptacle type: Since 1996, the National Electrical Code (NEC) has required 4-conductor circuits for electric ranges, ovens, and cooktops. This means the receptacle has four slots to accept a 4-prong cord plug. It’s a violation of code to install a new receptacle that is made for the old-style 3-prong cords.​

This preliminary involves removing the back access panel on the range, threading the power cord into the panel, then connecting the wires to matching screw terminals.

3-Prong vs. 4-Prong Plugs

Ranges and clothes dryers have a similar story. Prior to 1996 (it was actually closer to 2000 when the new rules were widely adopted), electric ranges and dryers were wired with three conductors: two “hots” and one neutral. The appliance body, or case, was grounded through the neutral so that the dryer cord and receptacle did not have a separate ground. After the code change, appliances began to be sold with the case ground separated from the neutral. This configuration calls for a 4-conductor power cord that has a separate ground wire that connects to the ground screw on the appliance. The old system worked just fine, but the new system is safer.

The 4-conductor rule applies only when you are installing a new receptacle, as in new construction or during major kitchen remodeling. The NEC still allows the use of existing 3-slot receptacles that work with the old-style 3-prong cords. If you are simply replacing a range and have a 3-slot range receptacle already present, you are allowed to install a 3-prong plug. However, you must configure the range wiring so the case ground is tied to the neutral terminal. Many ranges are sold with a metal bonding strip or wire for exactly that purpose. Consult the owner’s manual or the range manufacturer for instructions.

Tools and Supplies You Will Need

For the actual installation of the 120/240-volt receptacle, you will need the following tools and materials:

  • 4 x 4-inch metal electrical box (old work or new work box, as required)
  • 4-slot 120/240-volt range receptacle
  • Wire strippers
  • Screwdrivers

Instructions

These instructions assume that the range's power cord is already attached and that the circuit wiring and new 240-volt circuit breaker have already been installed. Make sure that the circuit wiring is shut off at the breaker box before connecting the receptacle. When installed by a professional, the circuit breaker is often left unconnected until after the receptacle wiring is completed.

Positioning the Receptacle

The location of the receptacle usually is determined by the appliance. Receptacles for freestanding ranges typically are accessible through an opening in the back of the range. When it’s time to plug in the range, you pull out and completely remove the drawer below the oven, then reach through the cavity from the front to get to the receptacle. Therefore, it’s best to mount the receptacle based on the range manufacturer’s specifications. Typically this is on the back wall behind the range, several inches above the floor and somewhat off-center in the cabinet space for the range. For some ranges, floor-mounting for the receptacle is preferred.

Install the Electrical Box

Once the proper cable is run from the circuit breaker box to the receptacle location, you can install a 4 x 4-inch receptacle box, either flush-mounted in the wall, or, if space allows, surface-mounted on the wall. Flush-mounted installations use "old-work" boxes designed for retrofit applications, while surface-mounted installations can use surface-mount metal boxes with rounded corners.

Connect the Cable Wires to the Receptacle

  1. Strip outer sheathing on the cable and then insert the cable into the box through one of the knock-out openings.
  2. Secure the cable to the box with a cable clamp appropriate to the type of box you are using.
  3. Strip about 3/4 inch of insulation from each individual insulated conductor in the cable.
  4. Insert the bare copper grounding wire from the cable into the grounding screw terminal on the receptacle (usually at the top of the receptacle), and tighten the setscrew firmly.
  5. Insert the white neutral wire into the neutral screw terminal (usually at the bottom of the receptacle) and tighten the setscrew.
  6. Insert the two hot wires (black and red) into the remaining screw terminals and tighten the setscrews.
  7. Tuck the wires into the box and mount the receptacle faceplate onto the wall box, securing it with the mounting screws.

Complete the Project

To complete the project, have the circuit breaker connected, turn it on, then plug in the range and test for operation.