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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:
Reader Question: Can I put an electrical receptacle up five feet from the finished 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
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
Reader question on citation for electrical outlet height in garages
(Jan 6, 2015) Kevin O'Hornett said:
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/
Reply: electrical practice suggestion vs. code requirements: NEC 210.52(G)
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.
How many electrical receptacles are allowed on a 20-amp circuit? How many receptacles on a 15-amp circuit?
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.
Our photo (left) illustrates an electrical receptacle intended for use on a 20-Amp circuit.
Details about how to wire up an electrical receptacle are at ELECTRICAL RECEPTACLE CONNECTION DETAILS - where to connect black, white, red, green, ground wires.
Reader Questions & Comments on Which end of electrical outlets go "up"? The ground hole should be up, down, or sideways?
Can the outlet be installed any way? For example ground hole facing up, down, or sideways? thanks, - Anon
Reader comments on which way the electrical outlet should be installed: Ground connector up or down?
One comment regarding 'inverted' outlet mounting (ground up, vs down).
(Aug 14, 2014) F. Rego said:
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
Reply: the position of installation of an electrical outlet won't affect its operation; insertion hazards at electrical receptacle slots
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.
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.
Research on which way the wall receptacle is installed: insertion of foreign objects into electrical receptacles
Reader Question: I don't have enough wire to lower receptacles on the wall
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
Reply: if you have to move an entire string of electrical receptacles complete re-wiring is faster and cheaper than adding a splice box for every device.
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.
Continue reading at JUNCTION BOX TYPES or select a topic from the More Reading links or topic ARTICLE INDEX shown below.
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Frequently Asked Questions (FAQs)
Question: what is the minimum height that indoor house wiring must be above the ground or floor level?
When running wire for a basement, is there a min height the wires must be off the ground? Not the outlet box, but the wire running through the joists. Justin Sheppard
No, Justin. But if there is the slightest danger that wires will be nicked by someone driving a nail into a stud though which the wires are run be sure to use steel plates to protect the wire where it passes through the studs. Simple nail plates are available at any building supplier.
Question: how do I install multiple electrical outlets (receptacles) along a wall?
putting in more than outlet on along a 12ft wall - Mike Tucker
Mike, if your comment is a question of how to put in more than one outlet along a 12 foot wall, yes it's perfectly permitted to exceed the minimum number of receptacles along a wall.
The wiring system is unchanged except that in some cases I recommend installing two different circuits and alternating which outlet is served by which circuit. That avoids overloading one circuit if you are plugging in lots of devices in one area.
Question: electrical outlet height requirements
I was looking at some height requirements on electrical outlets this is a very informational site.
Jerm, in the article above at HEIGHT above FLOOR for OUTLETS we give the data you want. Let me know if anything is unclear.
Question: can I add an electrical outlet on the wall where there is already a light switch?
I would like to wire in an outlet on the same wall where there is currently a light switch. Can I run wires from the light switch to power the outlet?The light switch is a 2 way switch. thank you. - Marv Walker 7/10/12
Well yes, maybe, sort-of.
Because a light switch is indeed switching a hot wire to the light, you've got power at the switch location. But depending on how the building is wired, you may not have an acceptable neutral wire, and in some still older circuits you may not have a safe ground wire.
Provided that you know how to work on electrical wiring without getting killed by electrocution, you (or your electrician) will open the switch box, carefully pull the switch assembly out enough to inspect for additional wires that may be present, and then use a VOM or DMM or even a simple neon tester to determine what wires are present.
To add a receptacle you need a proper hot, neutral and ground wire.
Watch out: if the "hot" wire in your light switch is on a 3-way circuit you may not always have power at your add-on receptacle.
Question: armor around wire through concrete?
I am running a new 15A outlet into the back of a bookcase in a 50 year old house with updated electrical. The wire runs out the back of the retrofit box and down through the concrete foundation into the crawlspace to a wire I plan to splice into. Do I need to put armor around the wire run through the foundation? It goes through open air for about 2 feet and there is no way to secure it to anything.
You need to look at the type and rating of the electrical wire to determine if it is permitted to bury it in concrete or not.
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