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EMT Conduit Protects Wires Where NM Cable Can't Be Used
EMT (electrical metallic tubing) is a form of rigid metal conduit used where circuit wires must run in exposed locations, such as in basements, along the surface of walls, or in outdoor locations. The Electrical Code generally requires extra protection for wires in these exposed locations, and EMT is one approved method for providing that protection for circuit wires where sheathed cable is insufficient. In EMT installations, individual wire conductors are pulled through the metal conduit to link the various fixtures and outlets along a circuit.
EMT can be fitted in any number of ways, including with mechanical elbows and sweep fittings that can be joined to straight lengths of conduit with union connections. These fittings quickly add to the cost of installation, however, so most pros turn corners by simply bending straight lengths of conduit to form sweeping angles. In addition to saving money, bended sweeps make it easier to pull wires through the conduit.
EMT is fairly rigid, but it's also easy to bend, provided you have the right tool and technique. The right tool is a conduit bender, and the right technique mostly involves measuring properly to account for the bend. Here's how the pros use a conduit bender.Continue to 2 of 4 below.
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Materials You'll Need
A simple conduit bender is the only specialty tool you'll need to bend EMT conduit. It is a standard tool owned by nearly all electricians, but for DIYers, the tool can be leased from home improvement centers or tool rental outlets.
Continue to 3 of 4 below.
- Tape measure
- Conduit bender (sized for conduit you’re bending)
- EMT Conduit
- Framing square
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Measuring and Marking for a 90-Degree Bends
The first step in making a 90-degree bend is to determine how long the bend needs to be. Let’s say that you’re running a piece of 3/4-inch conduit straight down a wall, then turn it 90 degrees to run it horizontally to an electrical box that is 12 inches away.
Look at the head of the conduit bender. You should find a notation about the take-up dimension. It might say something like, "Stubs 5 to arrow." This means that a 90-degree bend adds 5 inches to your horizontal measurement. A stub is what electricians call a 90-degree bend. The arrow is near the front end of the head and indicates the beginning of the bend.
In our example, the conduit needs to extend horizontally 12 inches from the vertical portion of the conduit. If the take-up dimension of your conduit bender is 5 inches, subtract 5 inches from 12 inches, giving you 7 inches.
Measure from the end of the conduit and make a mark at 7 inches to indicate the start of the bend. Slip the end of the conduit into the bender so the 7-inch mark is aligned with the arrow. This 7 inches, plus the "stubs 5 to arrow" will give you the total horizontal run of 12 inches, including the bend.Continue to 4 of 4 below.
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Making the Bend
Pull the handle of the bender back towards you while applying heavy foot pressure to the bender heel at the back side of the tool's head. Continue with a steady motion until the length of the conduit on the floor reaches the 90-degree mark indicated on the side of the bender's head.
- Tip: Keep firm foot pressure on the bender head while pulling back on the handle. If you don’t, the bender can slide on the conduit and the measurement will come out wrong.
Remove the conduit from the bender and check your work with a framing square. The two sides of the bend should align with the two legs of the square, indicated that the bend is exactly 90 degrees.
Next, check the length of the bend: Position the conduit with the long end on the floor and the short end pointing upwards. Measure straight up from the floor to the end of the conduit; in our example, it should be 12 inches.
If the bend is less than 90 degrees, you can put it back in the bender and bend it a little more. If you somehow end up with more than 12 inches on the horizontal, you can trim off the short end with a hacksaw or a tubing cutter. However, if you came up short, you'll have to start over with a new piece of conduit.