Stacked Kicks Sample
The drawing below illustrates 4 x 3in. EMT Conduits that are kicked from an overhead pipe rack to drop into an electrical distribution panel. The outside diameter of the conduits is 3-1/2 inches.
The Center to Center distance of the first kick is 30 inches, and each subsequent conduit is spaced an additional 5-1/2″ on center. The EMT connectors for the conduit are spaced 4-3/4 inches Center to Center in the top of the panel. The conduits are all kicked at a 60 degree angle to enter the panel. This creates a situation where the Center to Center distances between the kicked portions of the conduits to be only 4-1/8 inches, with a spacing between the conduits of only 11/16 inches.
Calculating the Kick.
The first conduit is kicked a distance of 30 inches.
Lets start with some metrics for the conduit bender, conduit, and bending shoe combination.
The bender is a Greenlee 881 bender with a 3″ EMT shoe.
Deduction = 24-1/4 inches Centerline radius of the bend is 16″ The bend will start at a distance of 6-1/2″ from the start mark. The Center of the bend will be at a distance of 14-7/8″ from the start mark. The Developed Length of the bend is 16-3/4″
The gain for the bend is 1.72″
The Developed Length (DL) of the Bend is the Centerline Radius of the Bend x the Angle of the Bend x .01745.
DL = 16 x 60 x .01745 = 16.752″
Gain = Tan(Angle/2) x 2 x Centerline Radius of the Bend – the Developed Length.
Gain = Tan(30) x 2 x Centerline Radius – DL
Gain = .5774 x 2 x 16 – 16.752 = 1.732
Each bending shoe also has a Start Mark Distance (SMD). This the the distance between the Bend Mark you draw on the conduit, and the location where the bend actually starts. With this bender/shoe/conduit, the SMD is 6-1/2″
The Cosecant of 60 degrees = 1.1547
A 30″ kick = 30 x 1.1547 = 34.641. This is the Center of the Bend. We now have to deduct half of the Developed length, SMD, and the Gain.
Start Mark = 34.641 – 8.375 – 6.5 – 1.732 = 18.03″ = 18″
This is where to mark the conduit for the placement of the shoe in the bender.
Stacked Kicks Sample Drawing