How to Make Expansion Joints in Schedule 40 for an Electric Service

Schedule 40 PVC pipe is commonly used in electrical applications. Paying close attention to how this pipe expands and contracts is the key to preventing the pipe from becoming damaged due to temperature changes. Adding expansion joints to schedule 40 piping can help reduce pipe damage due to excessive expansion and contraction of the piping caused by temperature changes. These expansion joints are not difficult to add. They only require installing a few extra feet of wire.

Schedule 40 PVC pipe
90-degree elbows
PVC cement
PVC saw

Instructions

- 1
  Place a 90-degree elbow onto the main PVC pipe at the location you want to start an expansion joint. Place a length of schedule 40 PVC pipe from this first 90-degree elbow to a second 90-degree elbow. The length of this pipe should be "B."
- 2
  Extend a second piece of PVC pipe from the second elbow to a third elbow. The length of this pipe will be "A." From the third elbow, extend a third piece of PVC pipe, for length "B," to a fourth elbow that will connect back to the main pipe.
- 3
  Calculate the length of pipes "A" and "B." The length of "A" equals 0.72 times the square root of the pipe outside diameter times the thermal expansion of the pipe in inches. The length of "B" uses the same formula, except the 0.72 is replaced by 1.44. Once the pipes are cut to length, use PVC cement to connect the pipes together.

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