Expansion Fittings Required?

[steve holt]

Could someone refresh my memory (or tell me I have been doing it wrong all this time). I am trying to find documentation as to when expansion fittings are required when crossing a building expansion joint. I was told by a structural engineer many years ago, that if I am running my conduits on a suspended rack, that I do not need to install expansion fitting when crossing that joint. The reasoning was, that the racking system itself would allow for any slight movement in adjacent structures.

 

[infinity]

I tend to agree with your theory for suspended racks but we always install them anyway when crossing a joint. Here's the relevant section.

300.4(H) Structural Joints. A listed expansion/deflection fitting
or other approved means shall be used where a raceway
crosses a structural joint intended for expansion, contrac-
tion or deflection, used in buildings, bridges, parking ga-
rages, or other structures.

 

[Smart $]

What matters is whether the conduits run straight into any securely fastened termination enclosure... which would need expansion/contraction/deflection joints. If the conduit runs permit deflection, such as all L-shaped runs, then the X/C/D joints would not be necessary (but Code still requires them).

 

[Gilf]

Also see NEC Article 352.44 about thermal expansion.