Help understanding PVC expansion fittings

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
Keep in mind the temperature when you install it. If it's hot, it'll be mostly shorter; if it's cold, it'll be mostly longer.
 

kwired

Electron manager
Location
NE Nebraska
Had to read that twice. ;) I think you meant if its hot on the install then it will get shorter when cold.
If you read instructions for the expansion fitting they usually mention this, you need to set the thing at installation according to what installation temperature is. Also if total movement of the run is more than the length of the expansion fitting then you need multiple expansion fittings in the run.
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
If you read instructions for the expansion fitting they usually mention this, you need to set the thing at installation according to what installation temperature is. Also if total movement of the run is more than the length of the expansion fitting then you need multiple expansion fittings in the run.
Which can cause some problems equalizing the motion over both expansion couplings unless you tie down the center point if the run.

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GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
But the run doesn’t get longer - that’s what the expansion joint is for.
Picture a straight run between two fixed boxes. This distance between boxes never changes. As the conduit expands, the expansion joint “absorbs” the increase in pipe length!
Not true when one purpose for the expansion joint is to accommodate motion of one or both termination boxes.


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