Height & spacing of electrical receptacles or "outlets" in buildings:
Requirements for electrical receptacle (outlet or wall plug) spacing, height, and clearances in buildings. In general electrical receptacles are installed along building walls such that at no point along the wall is the distance to the nearest electrical receptacle more than six feet - i.e. receptacles can be spacesd 12 ft. on center. Details about spacing, height, and clearance for receptacles are provided in this article.
This article series describes how to choose, locate, and wire an electrical receptacle in a home. Electrical receptacles (also called electrical outlets or "plugs" or "sockets") are simple devices that are easy to install, but there are details to get right if you want to be safe.
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An electrical outlet must be properly located on the wall, according to local electrical codes and the National Electrical Code. Examples of proper electrical outlet locations are shown in our two sketches below, courtesy of Carson Dunlop and in the following list of electrical outlet location requirements:
Tub-Shower clearance: Keep electrical receptacles at least three feet (one meter) away from a tub or shower.
Electric baseboard clearance: Keep electrical outlets offset above and to the side of vanity sinks, not right over the sink (left hand sketch below)
Electric baseboard clearance: Keep electrical receptacles off to one side, not right over electric heating baseboards to avoid overheating and possibly melting electrical cords draped over the heater (a fire risk) - see photo at below right, courtesy of Timothy Hemm.
Outlets in floors, countertops: Generally we do not mount electrical outlets flush in countertops or floors, though in some codes and jurisdictions the inspector may require that special (protected) floor-mount electrical receptacles be installed in order to meet the requirement that electrical outlets are available within six feet in any direction along a wall, and where no "wall" is available to install such receptacles (such as along a sleeping loft).
Garage electrical outlet location: In the garage electrical outlets should be 18" or more above floor level.
Before I contact an electrical contractor, I would like to know whether there are any Michigan electrical codes that apply to the "HEIGHT" above floor level - when adding a new (GFCI) A/C outlet to an existing residential home?
Specifically: I very much need to add a dedicated outlet in my bathroom to feed a nice quartz (1,500 W) wall space heater. And - to avoid a messy cord situation, I want to locate the outlet "up" (about 5 feet) off the floor - with a 60 min. wall timer in series.)
Is this OK? (The outlet will be more than 4 feet from the bathtub).
Thanks for your great website! (I read through - but couldn't find the answer to this.) - T.V.M., Grand Rapids MI
Because local building code jurisdictions may have their own local requirements, I'd give a call to your local building department and ask (please let me know what happens).
Most of the sources we have reviewed for details about the required height of electrical receptacles above the floor (see Mike Holt's Forum for example) assert that there is no National Electrical Code (NEC) specification of the height of wall-mounted electrical receptacles in homes. [After all, we regularly install a ceiling-mounted receptacle to power garage door operators.] One electrician cited 5'6" maximum above floor level for receptacles meeting the 6' horizontal spacing rule (NEC 210-52) . So you'd be OK with your high receptacle.
Just be sure it's a GFCI-protected receptacle as you're installing in a bathroom, and that the circuit amperage is high enough to operate the electric heater safely.
If your bathroom might need to meet Americans with Disabilities Act standards, you'd want to respect those heights - the ADA (Section 4.2.5 and 4.2.6) requires that outlets be at least 15" above the floor and switches and outlets should not be more than 48-54" (the variation is due to other conditions).
Our photo (left) shows an electrical receptacle mounted just about 2" above the finished floor - which is ok except for the ADA requirements, but that zip cord wiring that is run into the wall is improper, unsafe, and a fire hazard.
Here are some general guides: (heights pertain to electrical receptacles mounted in walls except where we note switches or other devices)
Example CA code on layout and heights http://www.sanjoseca.gov/building/PDFHandouts/5-7CommercialReceptacle.pdf
Readers of this article should also
see ELECTRICAL DEFINITIONS and
also SAFETY for ELECTRICAL INSPECTORS. Our photo at page top is not an example of a proper electrical outlet installation.
This website provides information about a variety of electrical hazards in buildings, with articles focused on the inspection, detection, and reporting of electrical hazards and on proper electrical repair methods for unsafe electrical conditions. Critique and content suggestions are invited. Credit is given to content editors and contributors
(Jan 6, 2015) Kevin O'Hornett said:
Hi, Dan, Re: Garage electrical outlet location: "In the garage electrical outlets should be 18" or more above floor level." Is this a personal recommendation based on your own knowledge regarding the potential for arcing/sparking at receptacle outlets under certain conditions or do you have a specific NEC or other authoritative regulatory document reference which specifies a minimum 18" height?
Note: PROSPEX owner Kevin O'Hornett has been a consultant and advisor throughout the U.S. and in Canada for the past twenty-two years. He also taught at Arizona SunTech from June of 2002 through May of 2004. Mr. Hornett can be reached at Prospex, P. O. Box 80 - Golden, Colorado 80402, Phone: (303) 517-1980 Website: http://www.prospex.us/
Short answer: garage receptacle height is a practice suggestion not an electrical code requirement. NEC 210.52(G) requires at least one receptacle, in addition to those for specific equipment, to be installed in each attached garage and in each detached garage with electric power.
However in the U.S. the NEC does not specify a height for electrical receptacles installed in a residential garage.
IMO the origin of the 18" minimum electrical receptacle height above the floor in residential garages is the same reason we elevate heating appliances: avoiding blowing up vehicle gasoline fumes presumably collected at floor level. Actually I see electricians putting the receptacles at 36-48" for reasons of easy access - also a practice not a code spec.
Of course GFCIs are required in the garage.
Commercial garages are a different matter.
I have found the assertion that NEC 505-9(c) could support a requirement for explosion-proof fittings on an electrical receptacle installed in a garage *below* 18" from the floor height - for the same reasoning I cited in the more general "opinion".
Also see NEC 210.23(A)(2).
I hope that when people are teaching home inspection or electrical wiring they will emphasize that building codes are a minimum requirement and can by no means include all possible situations nor all best practices.
We also don't route wires too close to places where the wires can be damaged by heat from a heating appliance or chimney, flooded, etc. as you'll see depicted in the two Carson Dunlop sketches below. Thanks to Steve for pointing out erroneous illustration link details, now fixed.
Reader question: How many receptacles can be wired To one 20 amp circuit No. 12. Wire - John K.
Our photo (left) shows a 20-Amp electrical receptacle - you can recognize it by that horizontal opening that makes the left-hand slot look like the letter "T" on its side.
In general, the Electrical Code [NEC] allows
Our photo (left) illustrates an electrical receptacle intended for use on a 20-Amp circuit.
Notice that extra horizontal slot? You won't see that on a 15-Amp electrical receptacle
Details about how to wire up an electrical receptacle are at ELECTRICAL RECEPTACLE CONNECTION DETAILS - where to connect black, white, red, green, ground wires.
Can the outlet be installed any way? For example ground hole facing up, down, or sideways? thanks, - Anon
One comment regarding 'inverted' outlet mounting (ground up, vs down).
While not specified in the code, I have noted that several electricians PREFER to mount a switched outlet so that the ground prong is up while mounting the non-switched outlets with the ground down. That way the homeowner can quickly determine a switched from a non-switched outlet. - Anon 9/5/12
(Aug 14, 2014) F. Rego said:
Thanks for the information - someone has said they like the ground prong up for a simple chance that if the ground prog is at the bottom and the extension cord gets somewhat loose and hungs that the two main prongs ( neutral /hot )are exposed and it by chance some metal item may fall it could short it out or cause a spark and ignite (example: drapes )as for the ground prog up all it will do is deflect it out of the way.
Our electricians at work told me that they prefer to install the outlets with the ground conductor up because it reduces the chances of a metal object (i.e. paperclip) falling off of a desk and landing between the neutral and phase conductor. With the ground conductor up, there is a better chance of such an object getting deflected or falling between the neutral and ground, which would be safer than falling between the neutral and phase conductor.
Although there is still a chance that an object might fall between ground and phase, it would be less likely than if the ground conductor was down. Because a typical 3-conductor plug is triangle in shape, an object is more likely to be deflected falling on the ground side than the phase / neutral side. - 2 Aug 2015
Anon, the position of installation of an electrical outlet won't affect its operation and should not normally affect its approval by the electrical inspector.
In some areas I see the outlet installed with the ground connector always "up" as in our photo at left, though to me that's less attractive than the position shown in our electrical outlet photo at far left.
I've also seen arguments expressing the OPINION that the position of the grounding pin connector might help resist the tendency of a plug to fall out of its connection. That's nonsense. If a plug is falling out of a receptacle, one of the two objects is worn or damaged and should be replaced to assure a safe, mechanically secure connection.
About upside down electrical outlets - thanks for the interesting comment. Unfortunately because there's no standard mount position associated with switched electrical receptacles, the next owner in a home will probably be confused unless the secret code is passed-on to everyone.
Well as the Poughkeepsie police desk seargeant told our renter Anna M. when she complained that the Amtrack trains three miles away were too loud and that the cops ought to do something about it, ... "well that's one I've never heard before".
The claim that ground-connector up might reduce the chances of a live short across the hot and neutral spaces of a wall plug is technically plausible, though the probability of a paper clip or hairpin happening to fall onto a wall plug exactly into the gap that might appear at a wall plugh that happens to not be plugged in far enough to prevent such contact seems to me to be very small.
It's the sort of explanation I used to make up before my friend Paul told me I was thinking too much and speculating too wildly.
What is a real hazard at electrical receptacles is the insertion by children (or an adult fool) of a paperclip or other foreign object into the electrically live slots. That concern has been addressed by research and by patents (Short 1989). None of the patent citations considered the bad luck of a falling paperclip shorting an electrical receptacle or its wall plug. They all focuse on inserted objects.
Thanks for the report, we'll keep it in the act.
I recently moved into a 3 1/4 story home, and I have a basement that I am trying to finish with drywall. The room is down to the studs and the electrical receptacles are about 4' up the wall. The Romex wiring is stapled, and there isn't enough wire to lower them.
It is way to much work for me to replace all of the downstairs wiring right to the breaker box, so I'm wondering if it is possible to add onto the existing wires and attach wire screws or marrets within the walls before I start adding drywall, or whether I should add some kind of junction box to contain the marreted wires in between.
My building code stipulations would differ in some cases because I live in Canada, but I just want to do the job right, and I do not want to take the chance of having any fire hazards, as I also have small children. - Dave 2/10/12
Dave,. you are correct to be careful about moving outlets or any other device when the existing wires are too short. The temptation is to just splice on an extension and bury that in the wall or ceiling: an illegal, improper, unsafe as well as really aggravating approach.
The proper approach is to add a junction box at each splice - we never splice 120/240V wires without including them in a box. You can reduce the wiring work a little by using plastic boxes instead of steel - avoiding having to also connect the box to the ground wire.
The proper approach also means that you don't then bury any of these splice-boxes in the walls either. Each box has to be brought to the surface and covered.
The result is a lot of work and expense and an ugly wall with an extra junction box and blind cover all along the wall over each of the now moved or lowered electrical receptacles.
Frankly I figure that especially as you've already got the wall open to the studs, if there are more than one or two receptacles to be moved you'll probably find it is actually much less total work to re-wire the entire circuit, allowing proper lengths of wires for each box. You might carefully remove and re-route the existing wire lower in the wall or you might buy all new electrical wire - depending on the age and condition of the existing materials.
Watch out: when removing wire that appears to be in good condition, if you nick the insulation you've created a new hazard.
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