What is the maximum distance that a receptacle wall box can be set back from the finished surface?

Installing electrical boxes and cables is made easy by following these recommended electrical installation codes. Don't just install your electrical wiring haphazardly, do it by the book of the National Electrical Code. This book of installation codes was developed to safely install all things electrical. Adhere to the rules to have safe and effective electrical wiring.

By installing the appropriate electrical boxes in the right manner, you'll have a safe and great looking installation. The electrical cables that run through walls and in and out of electrical boxes must be both supported and installed with adequate lengths for connections in accordance with these code for proper installation and ease of use.

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210.52(A) General Provisions

Provisions stipulating the placement of receptacle outlets for dwelling units are covered in 210.52(A) through (H). Last month’s “In Focus” covered both paragraphs and the fine print note in 210.52. This month, the discussion continues with the general requirements for receptacle placement. These general provisions apply to most of the rooms inside dwelling units. In every kitchen, family room, dining room, living room, parlor, library, den, sunroom, bedroom, recreation room or similar room or area of dwelling units, receptacle outlets must be installed in accordance with the general provisions specified in 210.52(A)(1) through (3). Within these rooms or areas, receptacle placement is determined by wall space. Don’t think that just because the name of a particular room is not included in this list, it is exempt. This provision states that compliance is also required for similar rooms or areas.

A diversity of names for similar rooms and areas may appear on blueprints, especially in larger houses. Various other names not specifically mentioned in this section of the Code include: sitting room (area), great room, bonus room, Florida room, morning room, keeping room, breakfast nook (area), study, office, media room, loft, studio and play (game) room. Other names, besides the ones mentioned here, may also be seen on blueprints. If there is any question about whether or not the general receptacle provisions are applicable in a room or area not mentioned above, consult the local authority having jurisdiction.

Certain rooms or areas in dwelling units not covered by the general provisions include bathrooms, laundry areas, basements, garages, hallways, outdoors and kitchen countertop surfaces. Each of these rooms or areas must comply with specific receptacle requirements listed in 210.52(C) through (H). Although this list includes basements, the general provisions are applicable to any part of a basement containing habitable rooms, such as a den, recreational room, play (game) room, etc. One location not mentioned is closets. Although receptacle outlets within closets are permitted, they are not required.

210.52(A)(1) Spacing

The amount of wall space determines the minimum number of receptacle outlets in a given dwelling. Wall space is measured horizontally along the floor line. Although the Code spells out requirements for the minimum number of receptacles in a dwelling, it does not limit the number of receptacle outlets. Receptacles must be installed so that no point measured horizontally along the floor line in any wall space is more than 6 feet or 1.8 meters from an outlet in that space. Following the floor line from a doorway, fireplace or similar opening, the maximum distance to a receptacle is 6 feet (1.8 meters). Sometimes this requirement is known as the “6-foot rule.” (See Figure 1.) Since the maximum distance to a receptacle is 6 feet (1.8 meters), the maximum distance between two receptacles is doubled. Therefore, the maximum distance between receptacles is 12 feet (3.6 meters). (See Figure 2.)

An easy way to understand and remember the placement of receptacles in dwellings is to imagine having a floor lamp with a 6-foot cord. Anywhere this lamp is placed around the wall, a receptacle should be within reach (unless the space is less than 24 inches wide). No extension should be required to supply power to this lamp. (See Figure 3.) Since a receptacle is required within 6 feet (1.8 meters) of a door opening, if the lamp is placed next to the opening, a receptacle will be within reach. Unless the wall is less than 2 feet wide, the 6-foot rule is applicable.

210.52(A)(2) Wall Space

This section contains three sentences that clarify the term “wall space.” As used in this section, a wall space is any space that is 2 feet (600 mm) or more in width. [210.52(A)(2)(1)] This provision is straightforward. If the space is less than 2 feet (600 mms) wide, it is not considered wall space; therefore no receptacle is required. If the space is 2 feet (600 mm) or more in width, then it is considered wall space, and consequently a receptacle outlet is required. For example, two bedrooms located in a dwelling unit are almost identical. In each room, a small wall space is located between the entry door and the closet door. The wall space between the doors in the first room measures exactly 2 feet (600 mm) wide. Since this room’s space measures 2 feet (600 mm), a receptacle outlet is required. (See Figure 4.)

The wall space between the doors in the second room is only 23 inches in width. In this room, no receptacle is required. (See Figure 5.)

Although receptacles are permitted in a space less than 2 feet (600 mm) wide, they are not required.

Note: Since these receptacles are located in bedrooms, they must be arc-fault protected. All branch circuits supplying 125-volt, single-phase, 15- and 20-ampere outlets installed in dwelling unit bedrooms must be protected by an arc-fault circuit interrupter listed to provide protection of the entire branch circuit. [210.12(B)] This requirement first appeared in the 1999 NEC but did not become effective until January 1, 2002. The rule changed slightly in the 2002 edition. In both editions, this requirement pertains to 125-volt, single-phase, 15- and 20-ampere outlets located in dwelling unit bedrooms. In the original rule, arc-fault protection was only required for bedroom receptacles. Now, in the 2002 edition, all bedroom outlets must be arc-fault protected.

Wall space includes the space measured around corners, regardless of whether the corner is an inside or outside corner. The wall space continues unless broken by a doorway, fireplace or similar opening. (See Figure 6.)

The space occupied by fixed panels (in exterior walls) is considered wall space and must be included when determining the minimum number of receptacle outlets. Sliding panels, also in exterior walls, are treated like doorways. Therefore, the space in front of sliding panels is not counted as wall space. Even if a window is designed to resemble a door, the space must be counted as wall space. For example, a dwelling unit’s back door is a glass panel door. A window, located on each side of the door, is almost identical to the door. Since the windows are fixed and do not open, the space they occupy must be counted as wall space. The space in front of windows extending from ceiling to floor must also be counted. For example, a sunroom is surrounded by floor-to-ceiling windows. Although there is virtually no wall space in the sunroom, receptacle outlets must still be installed in accordance with the general provisions. Floor receptacles can be installed if they are located within 18 inches (450 mm) of the wall.

Sliding glass doors contain fixed and sliding panels. Most sliding glass doors are comprised of two panels, one fixed and one sliding. While it is not necessary to count the space in front of the sliding panel, it is necessary to count the space in front of the fixed panel. (See Figure 7.)

Next month’s “In Focus,” resuming with 210.52(A)(2)(3), will continue discussion of required receptacle outlets in dwelling units.

During a remodel, customers and clients ask me lots of questions. Recently, I got a question about the rules for how high to mount receptacles, outlets, and switches. Several rules exist with regard to placing outlets, however, the height of a receptacle or wall switch isn’t part of the NEC code. At least, the code avoids rules with respect to the standard heights of both switches and outlets.

The General Rule of Thumb for Outlet Spacing

The primary rule is what’s known as the 6’/12′ rule. NEC 210-52 states the following (abbreviated for easier digestion):

Receptacles are needed in every room of a home such that no point on a wall is over 6′ from an outlet. This means that you need an outlet within 6′ of a doorway or fireplace. A long wall, however, may have up to 12′ between outlets. Any outlet above 5′ 6″ cannot be counted towards this equation. Floor outlets less than 18″ from the wall can.

There are also other guidelines that need to be followed. For example:

• Every hallway should have at least one receptacle if it is 10′ or longer in length
• Kitchen countertop outlets require at least two 20-amp circuits and must have GFCI protection. Allow no more than 4 feet between countertop outlets.

How High to Mount Receptacles or Outlets

Now to the point of this article. As for typical heights, that isn’t as well-regulated (and we’re glad for that). Generally, you want to mount receptacle boxes with the bottom of the box about 16-inches off the floor. Coincidentally, this roughly equates to the same height as your garden variety 22-ounce framing hammer. We still recommend using a ruler, however.

For kitchen countertops, how high you mount the receptacles depends on your layout. There are no height guidelines except to keep them under a maximum of 20-inches. This seems obvious since the top cabinets start at 18″). Placement somewhat depends upon how you intend to do the backsplash. If you mount the bottom of the box about 2-3 inches above the top of your tile, solid surface, or stone backsplash, you’ll have a nicely positioned outlet that is easy to access.

For refrigerators, you have some flexibility. Typically, we mount these outlets about 48-inches off the floor.

How High Do You Mount Light Switches?

Typically, you mount light switches about 48-inches high from the floor (on-center). This can vary, but we find this a great rule of thumb and very consistent with the builders and subcontractors in our area. We also tend to run these as a dedicated 15A or 20A circuit, though code may not require that.

Editor’s Note: We knew a guy who had all of all his switches set to be mounted 30-inches high off the floor. At first, we thought this was some kind of accommodation for a handicapped member of the family. After inquiring further, we found that it was simply to let him flip on the lights in every room without having to lift up his arm… While there was nothing technically wrong with this, we don’t recommend screwing up the potential resale value of your home over a trendy decision based on laziness or trying to be different! Follow the implied standards.

Building plans may have measurements that indicate on-center, top, or even bottom of box measurements. Just double-check your work to make sure it all makes sense and that you have sufficient ergonomics to activate all switches and access your outlets efficiently. Hopefully, knowing how high to mount your receptacles and switches lets you get on to the more important tasks of layout and design!