Parallel Kicks

Parallel Kicks

Parallel, or stacked kicks are one of the most complicated bends that electricians may be required to bend.  Parallel kicks should be:

1. Parallel at all points along the conduit
2. Spacing between conduits should be equal
3. Centers of the bend, or kick, should align

If any one of the  conditions listed above are not met, the other conditions may not be met either.  For example, if the kicks do not align, the center to center distance along the length of the conduits will not align, or be parallel.

The layout for parallel bends should begin at the layout of the trough, panel, or junction box where the conduits exit.  The distance to the center of the holes for the conduits from the wall, or back of the box, panel, or trough must first be determined.  If a piece of strut is going to be mounted to support the conduit, the depth of the strut must be included.  The drawing below, shows four 1/2" conduit running from a junction box with a top dimension that is 4 inches deep, by 16 inches wide.  A 16" length of 7/8" strut is mounted above the junction box.

Mistakes are often made because the electrician believes that it is possible to have the same center to center spacing for holes in the junction box, as for the center to center spacing between conduits.  You can see from the drawing below that it is not possible to do that if the conduits are kicked.

The angle used to make the kicks must be determined before the holes for the conduit are punched in the junction box. Use the triangle in the center of the drawing as an example.  The angle to kick the conduits is 30°, and the center to center distance between the conduits is 2".  The Center to Center distance between the holes in the box is 4".  The math is the same as that for bending an offset.  The Cosecant of 30° is 2.  2 times the 2" Center to Center distance between the run of parallel, kicked conduits = 4".

Therefore, in our example, the Center to Center distance between the holes in the junction box is 4"   Lay out the holes in the box, adjusting for the 7/8" strut, and drill or punch the holes.

Next, make the 90° bends at the desired length to get from the top of the junction box, to the predetermined height of the strut, or rack in the ceiling.

Determine the center to center distance of the kick for the first conduit, usually the closest to the wall.  In the drawing below, that distance is 10".  Use that same Cosecant of 2 to determine the distance from the center of the conduit riser, to the center of the kick.  In out drawing below, that distance is 20".

Note:  You may first want to make a sample bend, to determine the distance from the start mark on the bender to the center of the bend for the angle of kick that you have selected.

Measure 20" from the back of the 90° bend.  Subtract 1/2 the diameter of the conduit.  In this case, 1/2" conduit is about 3/4" in diameter, so subtract 3/8".  Now subtract a second amount equal to the distance from the center of the bend to your start mark.

Place the start mark of your bender on this new mark on the conduit, and make a 10" kick.  In theory, this should be exactly 30°.   I have found from experience, that the bends will be more consistent if they are bent to the distance, rather that the angle.  The angles being a little off looks better that the distance between bends being off.

As you can see from the drawing, the second conduit will run at 12" from the center of the conduit riser extending up from the junction box.  Using the same Csc(30°)=2, the length to the center of the kick to the second conduit is 24".  Use the distance that you determined for the center of the first kick, and just add 4" to each successive conduit.

The step by step processes to make the bends are:

1. Determine the angle to be used to make the kicks.
2. Determine the distance between holes in the panel, junction box, or trough, by multiplying the cosecant of the angle of the kick by the desired center to center distance between the conduits.  In the example above, the cosecant of 30° is 2.  The center to center distance between the conduits is 2.  The spacing between the holes is 2 x 2" = 4".  Remember to make the adjustment from the back of the junction box for any conduit support that will be used.
3. Determine the distance that the first, or closest conduit on the rack will run, parallel to the face of the panel, junction box, or trough.  In the example above, that distance is 10".
4. Determine the length of conduit to be kicked.  This is the distance determined in step 3, or in the example above, 10", times the cosecant of the angle of kick, which is 2 in the example.  The length of this section of conduit is 10" x 2 = 20".
5. Install the first conduit, and check for accuracy.
6. Determine the distance to the center of each of the remaining bends.  In the example drawing, the distances to the center of each remaining bend is 12" x 2 = 24", 14" x 2 = 28", and 16" x 2 = 32".

The drawing below shows a similar layout, except that the kicks are made at a 45° angle.  The Cosecant of 45° is 1.414, so the math becomes a little more difficult.  There are some advantages though.  The distance between the conduit centers is still 2", but the distance between holes in the junction box are only 2-13/16, instead of the 4" needed to make the 30° kicks.  The four conduits will now fit into a smaller junction box, in this case 12".  The distance between the conduit holes is now 1.414 x 2 = 2.828, or 2-13/16"

The drawing below also shows a similar layout, except that the kicks are made at a 60° angle.  The Cosecant of 60° is 1.155.  Again, the distance between the conduit centers is still 2", but the distance between holes in the junction box are only 2-5/16, instead of the 4" needed to make the 30° kicks.  The four conduits will now fit into a smaller junction box, in this case 10".  The distance between the conduit holes in the junction box is 1.155 x 2 = 2.310, or 2-5/16"

You can see that the higher the angle of the kick, the closer together the holes in the junction box are, and the smaller the junction box can be to fit the required number of conduits out the top.  The more compact the setup is, the closer the junction box may be to the first overhead strut.

There is also something happening here that you may want to note.  As the angle of the kick increases, even though the center to center distance between the straight part of the conduits remains constant, in the examples, at 2", the distance between the centers of the kicks is getting larger.  This is because the angle of the kick is increasing, but the radius of the bend is remaining constant.  The distances between the center of the inside conduit to the center of the outside conduit, at the center of the bends are:

• in the 30° kick example, the distance is 6.2117", or 6-3/16"  *
• in the 45º kick example, the distance is 6.4762", or 6-1/2"  *
• in the 60º kick example, the distance is 6.9282", or 6-15/16"  *

This is not a large amount, but if you compare the 3 example drawings, you will notice the difference.

There is one more example that I want to illustrate.  In the drawing below, each of the 4 conduits are different sizes.  The 4 shown are, from the left to right, a 1/2" EMT, a 1" EMT, a 2-1/2" EMT, and a 4" EMT.  When conduits of different sizes are installed together on the same rack, it is more common to make the distances between the conduits equal, rather that to make the center to center distance between the conduits equal.  In this example, 1-1/2" spacing is used between conduits.  This is a very common spacing to use.  It keeps the width of the rack fairly small, but there is still enough spacing to add or remove strut straps.  You can see from the drawing that the amount of the centerline kicks varies from conduit to conduit, and takes a little more work to lay out the bends.

We are using 45° kicks again, and the first conduit is still kicked at 10", as were the other drawings.  The Cosecant of the 45° angle is 1.414.  An easy way to layout the spacing is to lay the conduits on a table or the floor before bending, place pieces of 2x4 between them to get the 1-1/2" spacing, and measure the distances between centers.  Setting the first conduit at 10", causes the other conduit centers to be spaced at 12-1/4", 14-5/16", and 19-5/16".  The math to determine the lengths from the center of the 90° riser to the center of the kick is:

• 10" kick = 10 x 1.414 = 14.14 = 14-1/8"
• 12-1/4" kick = 12.25 x 1.414. = 17.3215 = 17-5/16"
• 14-15/16" kick = 14.9375 x 1.414 = 21.121625 = 21-1/8"
• 19-5/16" Kick = 19.3125 x 1.414 = 27.307875 = 27-5/16"

These calculations have nothing to do with the size of the conduit.  The center to center spacing of the conduits, and the size of the junction box are determined by the sizes of the conduits.

You may also notice that because of the different radii of each bend, there are differences in the spacing between the centers of the kicks.  If possible, you can help the appearance of the kicks by making all the bends on the shoe of the largest bender used.  If you place a 1/2" EMT conduit as the inside kick with the next conduit being a 4" EMT, the two conduits can come so close together that they contact.

The ability to keep the distances between conduits equal all becomes a near impossible task if a panel, junction box, or trough is used with pre-punched holes.  I have exchanged a blank end off the bottom of a panel with a pre-punched end from the top of the panel.  The best solution is to order panels, junction boxes, and troughs with blank ends and sides.  If this is not possible, the electrician may have to use double 90° bends, rather than kicks, or allow the bends to be closer together between the junction box and the kick because of using pre-punched conduit holes.

* I can accurately measure the distances, because the drawings are all drawn to scale in AutoCAD, and the program will measure the distances for me.