would it required to provide expansions fittings for runs of conduit (GRS) on rooftops due to the thermal expansions (winter / summer months)? I have typically seen expansion fittings used indoors and outdoors at building expansion joints but not particularly on rooftops?
expansion deflection fittings
- Thread starter Mike01
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- Illinois
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- retired electrician
Most of the time the final equipment connection is some type of flexible connection and that will allow enough movemenet unless the run is extremely long.
kingpb
Senior Member
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- SE USA as far as you can go
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- Engineer, Registered
The coefficient of thermal expansion (CTE) for rigid steel conduit is approx. 0.65 E-5 in/in/deg F. You can figure out how long of a run you can go without expansion joints. Don makes a good point on the connection end.
the coefficient of thermal expansion for PVC is (3.38 E-5 in./in./?F) is almost three times as high as for aluminum and almost six times as high as for steel.
Thermal expansion is typically only a concern for long straight runs.
the coefficient of thermal expansion for PVC is (3.38 E-5 in./in./?F) is almost three times as high as for aluminum and almost six times as high as for steel.
Thermal expansion is typically only a concern for long straight runs.
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