120 240 Volt Wiring

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Dave's Guide to Home Electrical Wiring:

Electric cooking ranges 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 with 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 120-volt current, but the heating unit of the dryer is powered by 240-volt current. An outlet receptacle is usually required only for freestanding 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 are written with freestanding upright range units in mind.

Circuits for Electric Ranges

Before wiring the end receptacle where you will plug in the range, there are some preliminaries. First, you'll need a 240-volt circuit of the proper amperage rating 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 from the circuit breaker panel, this is almost always a job for a professional electrician.
  • 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 of the range outlet.

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 a 3-wire cable, including white, black, and red wires, plus a bare copper ground wire.

The National Electrical Code (NEC) has different rules for different types of ranges. Drop-in ranges are usually hard-wired, and the circuit conductors must be sized to exactly match the wattage on the nameplate rating of the appliance.

But 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 to handle only 8,000 watts.
  • This means that for this 12,000-watt oven, 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.

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Freestanding vs. Drop-In Ranges

Another preliminary step is connecting the appliance power cord to the range.

Most ranges do not come with the power cord attached; this is a component you must buy separately and connect yourself. Unlike the installation of the circuit, 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 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 involves removing the back access panel on the range, threading the power cord into the panel, then connecting the wires to matching screw terminals. 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.

Types of Wiring

After the code change, appliances were sold with the case ground separated from the neutral. This configuration calls for a 4-conductor power cord with 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. 2-gang device box. 4-slot 120/240-volt range receptacle. 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. The location of the receptacle is usually determined by the appliance. Receptacles for freestanding ranges are accessible through an opening in the back of the range.

When it’s time to plug in the range, you will 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. Once the proper cable is run from the circuit breaker box to the receptacle location, you can install a 2-gang device 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. Strip outer sheathing on the cable and then insert the cable into the box through one of the knock-out openings.

Secure the cable to the box with a cable clamp appropriate to the type of box you are using.

White Wires

Strip about 3/4 inch of insulation from each individual insulated conductor in the cable. 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.

Insert the white neutral wire into the neutral screw terminal (usually at the bottom of the receptacle) and tighten the setscrew.

  • Insert the two hot wires (black and red) into the remaining screw terminals and tighten the setscrews.
  • Tuck the wires into the box and mount the receptacle onto the wall, then install the faceplate, securing it with the mounting screws.
  • Have the circuit breaker connected, turn it on, then plug in the range and test for operation.
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A non-double phase electricity service of 120/240V is made available to various homes in North America. The inbound power of 240V is divided into two branches. Either of the branch has the capability of providing 120V hot to neutral which makes it possible for the two branches to supply a combined power of 240V which is utilized for cook stoves and air conditioning compressors.

Each home has a circuit which is responsible for providing electricity for the lights, built-in appliances and receptacles.

Electrical Wiring Video #2

  • The circuits have wires and conductors which are grouped with respect to color, wiring type and size. The color of the wire’s insulation determines the work to be done by the wire.
  • Proper knowledge of the message being communicated by these colors will greatly assist you in working safely and without stress whenever you are faced with the challenge of correcting an electrical fault or implementing enhancements or repairs in your electrical systems.
  • You must also ensure that the connections are properly done and organized. For a wire to be used in the United States, the color must be in accordance with the National Electrical Code (NEC) requirements.
  • A Word of Warning: Consistently make use of a line voltage meter or circuit tester to find out whether a cable is “hot” or “live.” Never rely on the color of the wires alone.
  • Where you live determines if your home’s circuit wiring will be done with either individual conductors which passes via a hollow metal conduit or any of the three cable types. A wire is a factory product of an assembly of conductors in either a sheath or an outer coat.
  • Plastic sheathed or The Type NM (NonMetallic) cable is extensively used for house wiring circuits. Modern Type NM cables have distinct color sheathing which signifies the size of the conductors: Yellow for 12 AWG conductors, White for 14AWG (American Wire Gauge) conductors, and Orange for 10 AWG conductors.
  • The Type NM cable may also have a mark on the cable sheath of the cable. This indicates the size as well as the form of the conductors inside, also as well as other info “14-2/G,” for instance, reveals that that cable got two insulated, current-carrying conductors plus one grounding conductor, size 14 AWG.

Type MC (Metal Clad) and Type AC (Armor Clad) are the other two forms of cable which are always used in the extension of a system wired with metal conduit.