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LIGHTNING PROTECTION SYSTEMS
LOW VOLTAGE BUILDING WIRING
LOW VOLTAGE TRANSFORMER TEST
MAIN ELECTRICAL DISCONNECT
MAIN DISCONNECT AMPACITY
MOISTURE SOURCES in PANELS
MURRAY SIEMENS Recall
PHOTOVOLTAIC POWER SYSTEMS
PUSHMATIC - BULLDOG PANELS
REMOTE ELECTRIC POWER, PHOTOVOLTAIC
RUST in ELECTRICAL PANELS
SAFETY for ELECTRICAL INSPECTORS
SE CABLE SIZES vs AMPS
SIEMENS MURRAY Recall
UNDERGROUND SERVICE LATERALS
VOLTS / AMPS MEASUREMENT EQUIP
VOLTAGE MEASUREMENT METHODS
WIND ENERGY SYSTEMS
WIND TURBINES & LIGHTNING
ZINSCO SYLVANIA ELECTRICAL PANELS
Locating electrical receptacles: where should electrical receptacles (outlets or wall plugs) be located?
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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The Six Foot Rule for Receptacles
A basic guideline for locating and spacing electrical receptacles in a residential building is that at no spot along the length of any building interior wall should the distance to the nearest receptacle be more than six feet. This means you are placing wall receptacles at twelve-foot intervals or less; some wall designs and room layouts will of course reduce this number.
Clearnce Spacing Rules for Receptacles
In addition to the fundamental requirement that no space along a wall is more than six feet from an electrical receptacle, 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:
Here are some general guides for spacing clearances for electrical receptacles: (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
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.
Readers of this article should also see ELECTRICAL CODE BASICS, 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.
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.
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Frequently Asked Questions (FAQs)
Question: how to wire up a pair of receptacles in one electrical box
Channing, re Hooking up a Pair of Receptacles in One Electrical Box:
That's a perfectly acceptable use of the second pair of screw terminals you see on the receptacles.
However a better practice when wiring up a quad-plex of electrical receptacles is to place left and right or upper and lower receptacles on separate electrical circuits - thus reducing the chances of overloading the circuit when many things are connected simultaneously. There are two approaches: you can wire the left and right duplex receptacles each to different individual electrical circuits, or you can wire the upper and lower half of the pair of duplex receptacles to different electrical circuits.
Wiring a Split Receptacle to Two Different Electrical Circuits
If you choose to wire the upper and lower duplex receptacle openings to different circuits, we call this the "split receptacle" wiring method, because we are splitting the individual duplex receptacle upper and lower connectors onto two different circuits.
Our photo (left) shows an electrical receptacle that is being wired to a single circuit. The white neutral wire is connected to the silver screw (left side of our photo).
If we were wiring this electrical "outlet" as a split receptacle, we'd want to feed the upper and lower halves of the device from two different electrical circuits.
To do so we'd have to break away the "breakaway" connecting tab pointed to by our orange arrow.
Daisy Chaining Receptacles in Separate Electrical Boxes
If your two receptacles are in different locations and thus in different electrical boxes, your circuit that wires the second or "downstream" receptacle can be powered by those same extra terminal screws on the first or "upstream" receptacle. You'll need to run a wire from the first receptacle through the wall into the second electrical box of course.
Wiring Electrical Receptacles on a Single Circuit In Parallel
In some jurisdictions electricians to not "daisy chain" receptacles in the same box together by using the second pair of screws on each one. Rather the circuit enters the box and using twist-on connectors, short pig-tail wires are connected to each receptacle at the proper screws. This approach requires a larger electrical box as it will contain more connections, connectors, and so needs more room.
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: When adding an electrical outlet in a garage, what's code: metal or plastic junction box?
I am putting outlet in garage wall that has kitchen on the other side. What is code, plastic or metal? I would think in a garage fire that a plastic box would melt and fire would go through the wall faster? - Steve Smith
Steve both plastic and metal receptacle boxes are code-approved and neither, properly installed and wired, should violate the fire-rating of the wall.
Question: how many electrical receptacles are allowed on a 20-amp circuit? How many receptacles on a 15-amp circuit?
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.
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 prope 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 hazrd.
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.
Question: AmI allowed to add one more outlet onto an existing string?
I have an existing outlet being used for lamps I wanna run one more outlet shares from the hot on is it okay? - PHantum 113 8/1/12
Question: I am trying to hook up two receptacles from a single line pair
I’m attempting to wire two separate receptacles from one (line) wire, not in-line one after the other but effectively as a “Y” from a junction box with two load lines out (one to a north wall receptacle and the other to a south wall receptacle in my barn).
Using screw-on connectors, I connected the three black wires together; the three white wires together; and the three green wires to a pigtail screwed into the junction box. One receptacle works fine, but plugging anything into the other receptacle trips the circuit breaker. If this is not the correct wiring configuration within the junction box, what is the solution? - Robert 8/9/12
Question: which way is "right side up" for electrical outlets - more views
One comment regarding 'inverted' outlet mounting (ground up, vs down).
Reply: secret codes are confusing
Question: I need to add a light, fan, and fan switch to an existing bath - I can't find where to kill the power
very informative article thumbs up . I havea question tho.
Question: which circuit is better to use when adding a closet light
If I want to add light to closet, which circuit is it better to pull from? I have access to 120 plug and switches in outside wall facing away from closet that could be pulled into closet. Also, can you help explain the two different wiring configurations on my non GFI plugs. On two different plugs on different walls the plugs are 8 wire push in style (4 hot and 4 common), but the wiring config is different between the two plugs. One one all white and black are inserted in the bottom 4 connectors with tabs in place. On another same style plug, one set of 4 wires (2 blk and 2 white) are inserted in bottom left row, and other set of 4 wires are inserted in opposite side top row. These plugs are not controlled by switches. Thank you. - Chris 12/30/12
In my OPINION, it's best to connect a closet light to the room lighting circuit if possible.
About your other question, I'm a little confused by the query, but in general, receptacles and switches often have more than one permittted connection point, such as under a screw terminal, on older devices via a back-wiring push-in connector (something we do not recommend using), or on newer devices a side-clamp operated by a screw.
In all events, regardless of which connection point you are using, receptacles and switches have a designated side or screw or connector set for the white (neutral wire) (typically the side that has a silver colored screw and that is marked NEUTRAL on the device) and for the black (hot wire) (typically the side that has a brass-colored screwe and is marked LINE or HOT or BLACKI).
Questions & answers or comments about how to install and wire electrical outlets or receptacles in buildings.
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