How to Install Conduit to Protect Wiring in Your Home

Metal conduit helps protect wires and keep you safe—here's how to install it.

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Conduit offers superior protection and safety for wires. Even if local codes permit NM (non-metallic) or armored cable in a basement, garage, attic, or crawlspace, consider installing conduit to protect wiring.

There are many different types and thicknesses of conduit. EMT (electric metallic tube, also called thin-wall) is strong enough for most interior home installations. Outdoors, use IMC (intermediate metal conduit) or PVC conduit. Codes have detailed rules regarding conduit size, but generally, 1/2-inch conduit is large enough for five or fewer wires; 3/4-inch conduit is used for more than five wires. When in doubt or if you might run more wire in the future, buy the larger size—it doesn't cost much more.

Metal conduit may serve as the path for grounding, or local codes may require you to run a green-insulated ground wire. If you use PVC pipe, you need ground wire, either green-insulated or bare copper. If there's no ground wire, make sure all the metal conduit connections are firm; a loose joint could break the ground path.

Save time by buying prebent fittings for your conduit. A coupling joins two pieces of conduit end to end. A sweep makes a slow turn, allowing wires to slide easily, while a pulling elbow makes a sharper turn. Setscrew fittings are commonly used with EMT conduit; they provide strong but not waterproof joints. For weathertight joints, use IMC conduit and compression fittings.

Often, it's easiest to make a drawing of your proposed installation and have a salesperson help you assemble all the parts you need—conduit, sweeps, elbows, boxes, and clamps. And make sure to buy plenty of wire.

What You Need

  • Metal or handy boxes
  • Screws
  • Screwdriver
  • Offset fitting
  • Measuring tape
  • Conduit
  • Hacksaw
  • Conduit reaming attachment
  • One- or two-hole straps

Step 1: Anchor Boxes

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Anchor metal boxes to the wall with screws. Use handy boxes with rounded edges and metal covers for exposed wiring. An offset fitting allows the conduit to run tight up against the wall.

Step 2: Measure Conduit

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Once you install the boxes, measure the conduit for cutting. The surest method is to hold a piece in place and mark it rather than using a tape measure. Remember that the conduit slides about an inch into each fitting.

Step 3: Cut Conduit

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Cut the conduit to fit with a hacksaw. Don't use a tubing cutter, which creates sharp edges inside the conduit that could damage wire insulation. Remove the burrs inside and out with a conduit-reaming attachment on a screwdriver.

Step 4: Slide in Conduit

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Slide the conduit into a fitting and tighten the setscrew. Test to make sure the connection is tight. (If you are not installing a ground wire, these connections are critical for grounding.)

Make sure the wires have ample room inside the conduit to slide through easily. Codes have detailed rules regarding conduit size, but generally, 1/2-inch conduit is large enough for five or fewer wires; 3/4-inch conduit is used for more than five wires. When in doubt or if you might run more wire in the future, buy the larger size—it doesn't cost much more.

Step 5: Anchor Conduit

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Anchor the conduit with a one-or two-hole strap at least every 6 feet and within 2 feet of each box. The larger the conduit, the closer the straps need to be. Check with local codes. You should drive screws into joists or studs, not just drywall.

Bonus: How to Install a Pulling Elbow

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With every turn, it gets more challenging to slide the wires through a conduit. Install a pulling elbow if the conduit makes more than three turns before entering a box. Never make a splice here; use it as an access point when pulling wires.

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