Expansion fittings for PVC every 20ft.?

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stuartdmc

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Newport Beach, Irvine, CA
I have installed two runs of 2? schedule 80 sun resistant PVC on the side of a retaining wall the wall is covered with ficus trees to where you cant really see the conduits, we have painted the conduits to blend in with the wall the conduit runs about 100ft. to a disconnect and then runs another 100ft then dips underground.
My inspector is saying that I need to install EXPANSION FITTINGS every 20FT.? I have never heard of this Have any of you?
 
stuartdmc said:
Newport Beach CA.
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Here in Mass we can have a temperature change over 100 degrees. This can change a run of pvc over 4 inches over 100'. If you haven't install the wires it would be pretty easy to cut in the fittings.
 
teco said:
Here in Mass we can have a temperature change over 100 degrees. This can change a run of pvc over 4 inches over 100'. If you haven't install the wires it would be pretty easy to cut in the fittings.
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Thanks Mark, The wire is in. there is no Snow, no Rain, nothing but fun in the Sun.
The two runs are 100 ft. were at the ends they both dip down in the ground, so if they were to expand they could expand in one direction.
Is there a chance I can talk the inspector out of installing them?
 
My girls live out there not too far from you.
I will venture to say you may have a temperature swing through the year of about 30F. Using Table 353.44, you will still see an expansion of 1.22 in/100ft.

Since that is more than the permitted expansion as per 352.44, you will be responsible for some kind of expansion fitting. The average expansion fitting moves about 2-3 inches, so one should suffice for the 100ft run.
 
Please note that 352.30 requires the use of a supporting method that will permit the movement caused by thermal expansion and contraction. Many times PVC is installed with standard conduit fasteners that do not permit this movement.
 
OK so what are you all using to calculate yearly temprature variation?
From a local university's weather site
In the Willamette Valley few stations have had a maximum temperature greater than 98? F, or a minimum temperature lower than 16? F for over half of their years f record. Temperature of 90? F or more, occur only about six to eight days a year and those below zero occur on an average of once every 25 years. Here the mean temperatures average 38? F in January and 66? F in July. In the inland valleys of the southwest the average summer temperatures are about 5? F higher than in the northwest and maximums of 90? F or more occur 40 to 50 days a year.
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82? thus 85??
 
stuartdmc said:
I have installed two runs of 2? schedule 80 sun resistant PVC on the side of a retaining wall the wall is covered with ficus trees to where you cant really see the conduits, we have painted the conduits to blend in with the wall the conduit runs about 100ft. to a disconnect and then runs another 100ft then dips underground.
My inspector is saying that I need to install EXPANSION FITTINGS every 20FT.? I have never heard of this Have any of you?
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make sure you follow the manufacturers directions on how to install/support the expansion fittings....
 
Are expansion fittings only required for above ground PVC?

I have installed a hundred miles of PVC (underground) and never even HEARD of an expansion fitting until I came to the electrical message boards.

We don't install PVC runs above ground here, strictly EMT. PVC is too squirrly/wavy/looks bad.
 
tortuga said:
OK so what are you all using to calculate yearly temprature variation?
From a local university's weather site

82? thus 85??
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That would be the minimum I would use, more likely I would call it 100. I would also pay attention to Dons point about the supports.

Expansion joints wont help if the pipe can't move.

If you want it to still look good in a few years make sure it can move.

For a while I was doing vinyl siding the experienced guys would remind me that we do not 'fasten' vinyl siding we 'hang' it. Use the nail slots and do not drive the nails tight. If you do it will shrink in the winter but buckle in the summer.
 
Every 20'? Somewhere this inspector performed the calculation incorrectly. I would start with Carlon link from Stickboy and see if you agree with the inspector's requirement.
 
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