Avoid This Common Trap!

Avoid This Common Trap!

From the ,multiplier chart ,below, we can ,see that the, multiplier for, a 30º bend is exactly ,2. That's why, many electricians, will bend, nothing except 30º offsets; the math needed is simple and easy. This practice also results in unnecessarily sharp bends, harder wire pulls, and often additional junction boxes. It can also add time and money to the job and cause additional work during wire pulls. This practice is easy to avoid. Nearly everyone carries a cell phone with a calculator in it nowadays, and even if you don't you can still multiply two numbers. Do it right: Use a bend appropriate to the task. A large offset of 3 feet will probably need 45º bends, while a small one of a few inches can usually get by with 22º or even 10º bends. It is true that 10º bends can be difficult to get perfect, and that the math for 22º or 45º offsets takes a moment of effort, but neither is an excuse for shoddy workmanship.

A Last Word on Multipliers


A last word on multipliers: When bending large conduit, an angle finder is generally used to measure the precise angle being bent as the angle marks used on a hand bender are not stamped onto benders for large conduit. This raises an interesting possibility: Any angle desired may be used if you know the correct

What is an Offset Bend?

One of the more, common ,bends made, in electrical ,conduit ,is the offse,t bend: a technique, used to move ,a run of conduit, a set distance to one side, up or down. It is very rare that conduit can be placed in a straight line along the entire distance needed. There will usually be small projections in the way, other equipment to navigate around, or other reasons to move the conduit over some distance.

While bending conduit, one of the more important things to consider is the total number of degrees of bend between pull boxes. The NEC (national electric code) limits this number to 360º and some job specifications limit it even further. Fewer degrees of bend also result in an easier pull when it comes time to pull wire into the conduit—always a good thing. While bending an offset may be inevitable and necessary, the degree of the bend is variable depending on circumstances and the electrician doing the work.

An offset consists of two bends:
The first bend should change the direction the conduit is going.
The second should reverse that direction change. The result is a rather "Z" shaped piece of conduit, as shown in the pictures below.

The most common bend used is a 30º bend, followed by another of the same, resulting in a total bend of 60º, but this is not necessary in most cases. Bends of 10º, 22º, and occasionally 45º or even 60º, are marked on all hand benders and should be used when appropriate. The difference is in the multiplier, as discussed below.

Using the Multiplier When Bending an Offset

The multilplier is a number of the measured distance of the offset is multiplied by to obtain the distance between the two bends.

You should memorize this number for the common bends of 10, 22, 30, and 45 degrees. Many benders have the multiplier permanently stamped on the reverse side of the bender—a useful option for the beginning electrician. These numbers are also shown in the chart below.

Once the offset distance is measured, multiply that measurement by the appropriate multiplier from the chart. These figures are all in decimals, though most people will use a tape measure marked in fractions of an inch. The decimals must be converted to fractions to be useful. Few electricians will try to mark and bend conduit in increments of less than 1/8" (the bending process just isn't all that accurate), so the number needs to be converted to just such a fraction. I've listed the decimal equivalents of multiples of 1/8" in the next table. You probably already recognize half of them and the other half is easily memorized. Don't be afraid to round off your numbers— 1/1000" of an inch just isn't enough to worry about!

For example, let's suppose that the distance needed is 3½", and that we want to use a 22º bend. The multiplier for 22º is 2.6, and 3½" is 3.5" in decimal notation. Using a calculator, we find that 2.6 times 3.5 equals 9.1". Now 9.1" is very close to 9.125" (the difference is only .025") which we can see from the chart is 9 1/8". The difference between 9.1 and 9.125 is less than 1/32". That's probably less than half the width of the sharpie line you will draw on the conduit! Don't worry about it. Just use the 9 1/8" figure.