Rigid conduit Expansion, Building Expansion Joints

[Fordean]

In parking deck. Have to run RGS to replace severly deteriorated (RGS) in concrete. 40 years ago install. What is the Expansion on 270 feet for RGS 1 inch. I believe its in code book will go look when back in office. I believe expansion type fitting will be needed.

Wondering on Parking deck PVC coated MC type. But this will be below beams install now and 12'7" separations between I beam.

 

[masterinbama]

On parking decks we use a short section of seal tite at building expansion joints because they also move laterally.

 

[Smart $]

On parking decks we use a short section of seal tite at building expansion joints because they also move laterally.

That's okay if AHJ approves...

(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, contraction
or deflection, used in buildings, bridges, parking garages,
or other structures.

 

[Smart $]

... I believe its in code book will go look when back in office....

It's in Informational Note to 300.7(B)...

The coefficient of expansion for steel electrical metallic tubing, intermediate metal conduit, and rigid conduit is 1.170? 10⁻⁵ (0.0000117 mm per mm of conduit for each ?C in temperature change) [0.650 ? 10⁻⁵ (0.0000065 in. per inch of conduit for each ?F in temperature change)].

270' x 12"/ft x 0.0000065"/"-?F = 0.02106"/?F

If you have a yearly ambient temperature swing of say 100?F, your looking at a little over 2"... but don't forget that what you secure the conduit to also expands and contracts. I recall looking it up previously, and IIRC concrete exposed to the same ambient has a range for its expansion coefficient that encompasses that of steel. That means to me, there is no way for the laymen to determine the difference in expansion and contraction of the two.

 

[Fordean]

Cioncern

Cioncern

It's in Informational Note to 300.7(B)...



270' x 12"/ft x 0.0000065"/"-?F = 0.02106"/?F

If you have a yearly ambient temperature swing of say 100?F, your looking at a little over 2"... but don't forget that what you secure the conduit to also expands and contracts. I recall looking it up previously, and IIRC concrete exposed to the same ambient has a range for its expansion coefficient that encompasses that of steel. That means to me, there is no way for the laymen to determine the difference in expansion and contraction of the two.

THat is what my concern was. If I strap to underside of I beams (span 12'7") all 19 of them. That expands to. So at 270 feet. It will be tightly bond to beam. Which would hamper expansion. Im trying to figure to what extent.
I will place 2 expansion fittings evenly in run just to help it.

Thanks for response.