Basics of electrical conduit

Many jobs involving a single 90° bend are quite simple and require no advanced knowledge or expertise. A fundamental principle in all EMT Electrical Conduit installations is that the pipe should conform closely to the wall or ceiling finish surface. In other words, do not allow the raceway to take a shortcut through open space in a building interior. Nor, generally, should a diagonal route be taken even if that would reduce the amount of raceway and wire required.

Quite often a conduit run consists of a straight stub between boxes. To simplify the installation, you can postpone tying down one of the boxes until after the pipe is terminated. Another common, simple job involves running pipe from a box to an interior corner, known in the trade as a brick wall, where a conduit bend is needed. You can leave one or both legs long, then mark and cut them to fit after the bend is made. Alternately, and more elegantly, use the standard deduction for a given size conduit. For half-inch conduit, the deduction is five inches. For 0.75-in. conduit, the deduction is six inches. For IMC Electrical Conduit the deduction is eight inches. Usually the deduction is stamped on the bender.

Mark the conduit, minus the deduction for the conduit size. Put the conduit in the bender with the mark on the Rigid Electrical Conduit aligned with a mark on the bender, usually an arrow called the B mark.

Make the bend, being sure to bring the moving leg up until it is vertical.

These are the simpler conduit bends. Now we’ll look at some more complex procedures.

An array of pipe can be run from entrance panel to final destination without regard to appearance and it will probably work electrically, but the product would invariably be perceived as substandard. When a group of conduits emerge from the top, side or bottom of a panel, uniform spacing should be maintained as they follow parallel paths from room to room.

A plywood template is helpful in maintaining Flexible Metal Conduit spacing from start to finish.

To figure Flexible Metal Conduit Fittings for complex installations, it is often best to use trigonometric functions. The sides of all right triangles with given angles on either side of the hypotenuse conform to the same ratios regardless of the triangle size. These ratios can be found in readily available trig tables. And they can be used to find the sides, or working in the other direction, to find the angles.