An electrician's guide to conduit bending
Conduit bending is an essential skill used by electricians in the construction industry when they're installing electrical systems. The conduit is a safety feature that protects both the electrical wiring from damage as well as employees working inside the business.
Bending conduit is a skill involving trigonometric functions, which allow electricians to determine what angle they need to make the different required bends.
Different benders can be used to bend conduit. The most common type is the EMT bender, which allows the electrician to bend the conduit by hand. Some electricians use a power operated bender but these can be expensive. The EMT bender has a handle, a curved track and slot that prevents the conduit from slipping out of the curved track as the conduit is being bent. A hickey bender is used on rigid conduit because, as the name suggests, this type of conduit is more difficult to bend. The rigid conduit can be bent a little at a time with the hickey bender until the desired angle is reached.
Electricians need to calculate the angle and length of each bend. Imagine a triangle with a 90 degree angle and long hypotenuse. The vertical line is called the opposite side of the triangle and the horizontal side is called the adjacent side of the triangle. The 90 degree bend, or stub-up, is generally the first bend electricians learn to make. Most hand benders have a bending mark engraved onto their bender. The size of the conduit will determine whether a deduction must be made in the calculations. Before beginning, it is necessary to mark the conduit at the distance where the bend will begin. Then match the mark on the conduit with the engraved mark on the hand bender. Place your foot onto the hand bender and begin applying pressure onto the end of it while you use a squaring tool or level to ensure you get it to a 90 degree angle. A Cosecant is the length of the bend. A 90 degree bend angle on a half-inch diameter conduit measures approximately five inches.
The offset bend is used when the conduit must run from one plane to another. For example, if an obstacle lies between a straight run of conduit, the electrician must get around the obstruction and then get the conduit back onto a parallel plane so it still runs in the same direction. The distance from the centre of the first bend to the centre of the second bend must be determined before making the first bend. A 30 degree angle bend measures 10 inches centre to centre between the two angles. Making a 30 degree bend in conduit will place the handle on the hand bender straight up -- or 90 degrees from the floor. A 30 degree offset is the most common offset used by electricians because it is easiest to pull wire through this particular offset angle than through any other offset.
Three Bend Saddle
A three bend saddle is made to get around an obstacle and then guide the conduit back onto the originally established straight line.Working with pipes, beams or other smaller obstacles will cause an electrician to rely on this type of bend, which involves making three different bends to accomplish the goal. When completed, this type of conduit bend looks like a semicircle. The conduit is bent at 22.5 degrees for the two outside bends and at 45 degrees at the centre bend. The electrician must calculate the distance from centre to centre bend; when using these angles, the distance is generally 12 inches between outside bends. The 45 degree bend is made first after which the two 22.5 degree angles can be easily accomplished from either side.
The common steps in conduit bending are learnt during an electrical apprenticeship program or through experience. Step one involves the electrician cleaning burrs from the end of the conduit with a reaming tool. Step two requires him to measure the distance from the end of the conduit to the place where the bend must be made and then marking that distance. Step three has the electrician marking the middle of the bend. Step four involves verifying all measurements. Step five recommends the electrician look carefully at the markings and measurements one last time because once the bend is made, the conduit cannot be used for that particular place if the measurement is off and the angle is wrong. The final step involves the electrician marking a spot on the floor to ensure the conduit remains in the same place throughout the process and that it doesn't slip as it's bent.