Rigid conduit expansion joints.

[RMELECT]

Installing a new 1200a service in an existing commercial building. (4) 4" underground conduits from pad mount transformer to building. CT'd meter socket being used so coming out of the ground outside and going to LB into the back of the 1200a panel using rigid metal conduit and steel LB's due to location. Are expantion joints needed and if so where is this in the code. Thanks

 

[Dennis Alwon]

I don't see a section under RMC that states expansion is needed as it does for PVC. I know they make expansion fittings for rigid but I don't know when they would be needed.

 

[don_resqcapt19]

You need some method of complying with 30.5(J) and with a compete conduit run, an expansion joint is about the only method available.

 

[RMELECT]

I understand the 300.5(J) section but we were going to use steel 90'S, steel conduit nipples threaded onto steel LB's and stubbed through a block wall into the back of the switch gear inside. I understand if the equipment were mounted outside coming into the bottom. Thank you.

 

[Fred B]

300.7(B) simply indicates that raceway shall be provided with expansion fitting where necessary to compensate for thermal expansion. Informational note has some criteria for expansion of rigid per degree in change of temperature.