Farmer John
Member
Is an expansion joint required between the meter pan and a non-permanently-mounted service head with a 28' run using 1 1/4" RNC?
Expansion Joint
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mdshunk
Senior Member
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Nope, there's only one fixed point in that run... the meter can. Any thermal expansion will just cause the riser to "grow" with no problem. If there are building expansion joints/seismic joints being crossed, that might be a horse of another color.
Farmer John
Member
Expansion Joint
Thank you very much for your reply. I am very glad to hear you agree with my position. I am scheduled to appear before the Construction Board of Morris County, NJ tomorrow night (Thur. 4/26) @ 7:30 to argue that I don't need an expansion joint in this case. Can you provide me with some kind of authority to help prove my position here?
Thank you very much for your reply. I am very glad to hear you agree with my position. I am scheduled to appear before the Construction Board of Morris County, NJ tomorrow night (Thur. 4/26) @ 7:30 to argue that I don't need an expansion joint in this case. Can you provide me with some kind of authority to help prove my position here?
mdshunk
Senior Member
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For starters:
352.44 Expansion Fittings.
Expansion fittings for RNC shall be provided to compensate for thermal expansion and contraction where the length change, in accordance with Table 352.44(A) or (B), is expected to be 6 mm (1/4 in.) or greater in a straight run between securely mounted items such as boxes, cabinets, elbows, or other conduit terminations.
And, here's a link to the free NEMA document, "Expansion Joints for PVC Rigid Nonmetallic Conduit". It basically reiterates that the expansion fitting is for PVC between firmly fixed points. It also points out that the straps are designed to allow the raceway to "slide" as it grows and shrinks, should that happen to be brought up in the meeting.
http://www.nema.org/stds/expansionjoints-pvc.cfm#download
352.44 Expansion Fittings.
Expansion fittings for RNC shall be provided to compensate for thermal expansion and contraction where the length change, in accordance with Table 352.44(A) or (B), is expected to be 6 mm (1/4 in.) or greater in a straight run between securely mounted items such as boxes, cabinets, elbows, or other conduit terminations.
And, here's a link to the free NEMA document, "Expansion Joints for PVC Rigid Nonmetallic Conduit". It basically reiterates that the expansion fitting is for PVC between firmly fixed points. It also points out that the straps are designed to allow the raceway to "slide" as it grows and shrinks, should that happen to be brought up in the meeting.
http://www.nema.org/stds/expansionjoints-pvc.cfm#download
Okay. I see where the code has been very precise about when expansion fittings are needed. Is a service head considered a conduit fitting? That would make sense..... it is doing a mechancial job routing cables.... and fittings are not mentioned 352.44. At first I thought it was considered a conduit termination in which case there would be a case to have expansion concerns............... very interesting...........
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