Electrical wiring clearance distances from pipes & ductwork:

How far should you keep wires away from plumbing pipes or ductwork?

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.

Electrical Wire Clearances from Ducts & Pipes

What distance should be kept between electrical wires or boxes and nearby plumbing pipes or HVAC ducts? Some basic wire clearance distances are given in Carson Dunlop Associates' skectch above, used with permission.

Carson Dunlop Associates is a Toronto home inspection, education, and report writing tool firm.

[Click to enlarge any image]

In that page top sketch we show that

Electrical wire should be kept at least 1" away from radiator piping and heating ducts. A piece of insulation can be used to keep the wire separated from a nearby heating duct or pipe if necessary.

Electrical wire must be kept at least 6" away from a single-wall exhaust flue of gas fired heating appliances.

Electrical wire must be kept 9" ti 18" away from a single wall exhaust flue of an oil fired heating appliance like a boiler, furnace, or water heater.

Electrical wire must be at least 18" away from a single wall exhaust flue for a woodstove or coal stove

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 Associates sketches below.

Thanks to Steve for pointing out erroneous illustration link details, now fixed.

Also you'll note in the two Carson Dunlop Associates sketches just below that wires need to be routed through the center of wall studs, ceiling or floor joists, or if there is less than 1 1/4-inches of clear space between the wire opening in the stud or joist and the joist face you must use a nail plate

or NAIL STOPS(shown below)

to protect the wire from penetration from a nail or screw that someone may drive into the stud or joist later.

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2021-04-05 - by (mod) - gas line is allowed to cross an electrical conduit.

@Chris,

Typically A gas line is allowed to cross an electrical conduit. If those are buried the digging around that needs to be done by hand within 2 feet to avoid risk of damage. In any event it's your local building code compliance inspector who is the final legal authority and word on the question.

Details & more examples of this question discussed with several readers are

at GAS METER CODES & CLEARANCE DISTANCES

On 2021-04-05 by Chris

Adding a exterior gas line for an outdoor grill. The line will come off the meter and run parallel to the house. I am also tapping into an exterior outlet to run electrical to the outdoor grill kitchen. I read the table where it calls for a 12" vertical clearance between gas and electrical lines.

Electrical will be housed inside conduit. The electrical conduit will intersect the gas line at a perpendicular angle. My question being, is it ok for the electrical conduit to pass by the gas line so that I can then bury the electrical conduit 12" below the gas line that will be more superficial to the surface, or are the lines not allowed to pass each other that way? Thanks!

 

On 2019-12-05 by (mod) - NEC permits (pigtailed - not backwire daisy-chained) common 15A duplex receptacles on 20A (12 gauge) circuits.

Brad:

I think you're quite correct - you'll find that 15A receptacle citation in multiple sources and in the NEC;

However

Watch out: I just removed an over-heated, burning 15A receptacle on a 15A (not even a 20A) circuit into which a 1200W electric heater had been connected for months at a time. I suspect that the root problem was that the electrician installing the 15A receptacle used the push-in back-wire connectors.

You'll probably find that on a 20A #12wire circuit, newer 15A receptacles won't let the electrician connect the device by push-in backwiring - fortunately.

Thank you for the useful comment. I run across that same point. I'm glad to have it added here.

On 2019-12-05 by Brad

It's my understanding that the NEC now permits (pigtailed - not backwire daisy-chained) common 15A duplex receptacles on 20A (12 gauge) circuits. If I remember right, it's because no single 15A receptacle will be called upon for more than it's rated amperage by any appliance that comes with a 15A plug, but the entire circuit may sometimes (even routinely) be called upon to carry aggregate loads in excess of 15A. Am I wrong here?

I'm informed that the NEC now permits the use 15A-rated duplex outlets on multiple-receptacle 20A circuits wired with 12 gauge wire. The logic being that no single 120V outlet will be called upon to draw more than 15A, as there are virtually no equipment, appliances, lights, etc. that are rated at more than 12A that can now legally be sold with a 120V, 15A plug. Non-dedicated 20A circuits are by nature designed to handle multiple loads, so may exceed the rating of any individual load up to 20 Amps. 15A breakers and outlets must still be installed wherever 14 gauge wire is used on any part of a circuit.

On 2018-12-13 - by (mod) -

JM

I haven't seen that clearance distance given explicitly in building codes; clearances will have to at least respect the working distance around the heater as given in the manufacturer's installation and operation manual.

On 2018-12-13 by JMK

What is the minimum distance between and electrical receptacle and a residential water heater? I live in Los
Angeles county, CA.

jmuryk@juno.com

Reader 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

Reply:

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.

Reader Question: armor required around electrical wire run 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.

Thanks!
Tom - 7/19/12

Reply:

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.

 

Wires running in walls anywhere from floor level to seven feet above the floor (U.S.) or five feet above the floor (Canada) must be protected from nails driven through walls.

Our photo (left) illustrates a 6-inch NS-2 Nail Stop produced by Simpson Strong-Tie.

Simpson Strong-Tie catalogs these nail stops as Protecting Shield Plate Nail Stoppers.

Details about using these steel plates to protect electrical wire (and also pipes) in buildings are

at NAIL STOPS to PROTECT WIRES

 

Reader Question: how do I increase the projection of outlets into a room so I can add a kitchen backsplash

I am unable to find instructions on how to increase the projection into the room of existing electrical outlets so that I can tile the kitchen backsplash and have the outlets be at the appropriate depth for use and safety. Do I move forward the box to which the outlet is screwed and if so how? - Anne 3/22/12

Reply: use electrical box extenders - shop for an "electrical box extension" of the proper thickness

Anne,

Building suppliers like Home Depot and also your electrical supply house sell "box extenders" in varying thicknesses, made of plastic, code approved, for the purpose you describe. The electrical box extender is sized and shaped to match the electrical receptacle box to which it is to fit.

By removing the electrical receptacle from its mount on the existing box, the box extender is fit as a sort of large rectangular plastic washer, mounting between the existing box edge or surface and the mounting ears of the receptacle or switch.

Electrical box extensions are sold in plastic and steel and in thicknesses from about 1/8" up to an inch or even more. The plastic electrical "gang box extension" shown at above left is produced by Arlington Industries but there are several manufacturers.

Just choose an electrical box extender that brings your receptacles far enough forward to suit the thickness of the kitchen backsplash or tile.

Watch out: don't try a makeshift substitute using washers or junk - that's an improper and unsafe repair, leaving a gap around the electrical box sides.

Reader Comments:

Anne,

I'm in the midst of a remodel that posed the same 'problem'. Work box extender rings are available at Home Depot and Lowes in the electrical department.

They are plastic, color-coded frames that fit between the front edge of the box and the outlet/switch. The screws that secure the outlet/switch to the box also secure the frame in place.

The frames are available in multiple thicknesses. I suggest you take a tile sample with you so that you can get the correct thickness for your project. Depending on the thickness of the tile, you may need to combine two frames of different thicknesses.

While I was changing a failed plug I noticed that the box was too deep. I looked into extenders, and plastic ones (Arlington BE1) are less expensive. Are CSA approved plastic box extenders code compliant for homes? - Gary 7/19/12

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.

Reply:

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

• 10 electrical receptacles to be wired on a 15-Amp (#14 copper) wire circuit, and the Electrical Code [NEC] allows
• 13 receptacles on a 20-amp (#12 copper) wire circuit.
  
  Watch out: When purchasing the receptacles to use on a 20A circuit, be sure to also buy receptacles that are themselves rated for 20Amp use.
  
  You'll see that those least-costly receptacles found in a big pile at building supply stores are more likely intended only for 15-Amp use.

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.

 

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Continue reading  at ELECTRICAL RECEPTACLE POSITION: WHICH WAY UP or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• ELECTRICAL OUTLET, HOW TO ADD & WIRE - home
• ELECTRICAL OUTLET ADAPTER SHORT CIRCUIT
• ELECTRICAL RECEPTACLE ARC PITTING
• ELECTRICAL RECEPTACLE CONNECTION DETAILS
• ELECTRICAL RECEPTACLE COUNTERTOP SPACING
• ELECTRICAL RECEPTACLE COVER PLATES
• ELECTRICAL RECEPTACLE HEIGHT & CLEARANCES
  • ELECTRICAL OUTLET HEIGHT ABOVE FLOOR
  • ELECTRICAL RECEPTACLE POSITION: WHICH WAY UP
  • ELECTRICAL BOX RECESSED DEPTH IN WALLS
  • ELECTRICAL BOX RELOCATION WIRING
  • ELECTRICAL BOX FIRE SEPARATION DISTANCES
• ELECTRICAL RECEPTACLE LOCATIONS
• ELECTRICAL RECEPTACLE TYPES
• ELECTRICAL DUPLEX RECEPTACLE WIRING
• ELECTRICAL OUTLET, HOW TO ADD in OLDER HOME
• ELECTRICAL WIRE CLEARANCE FROM DUCTS & PIPES
• GAS METER CODES & CLEARANCE DISTANCES - includes clearance distances to electrical wiring & conduit

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ELECTRICAL WIRE CLEARANCE FROM DUCTS & PIPES at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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INDEX to RELATED ARTICLES: ARTICLE INDEX to ELECTRICAL INSPECTION & TESTING

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