Expansion Joint Required

[perryalbright]

300.7 Raceways Exposed to Different Temperatures.

(A) Sealing. Where portions of a raceway or sleeve areknown to be subjected to different temperatures,and wherecondensation is known to be aproblem, as in cold storageareas ofbuildings or where passing from the interior to the
exterior of a building, the raceway or sleeve shall befilledwith an approved material to preventthe circulation ofwarm air to a coldersection of the raceway or sleeve. Anexplosionproof seal shall not be required for this purpose.


(B) Expansion Fittings. Raceways shall be providedwithexpansion fittings where necessary tocompensate for thermalexpansion andcontraction.

Informational Note: Table 352.44 and Table 355.44providethe expansion information forpolyvinyl chloride(PVC) and for reinforcedthermosetting resin conduit(RTRC),respectively. A nominal number for steel conduitcanbe determined by multiplying the expansion length in Table352.44 by 0.20. The coefficient of expansion for steelelectrical metallic tubing, intermediate metal conduit, andrigid conduit is 1.170× 10−5 (0.0000117 mm per mm ofconduitfor each °C in temperature change) [0.650 × 10−5(0.0000065 in. per inch of conduit for each °F in temperaturechange)].Anominal number for aluminum conduit and aluminumelectricalmetallic tubing can be determined by multiplyingtheexpansion length in Table 352.44 by 0.40. Thecoefficientof expansion for aluminum electrical metallic tubing and aluminum rigid metal conduit is 2.34 × 10−5(0.0000234 mm per mm of conduitfor each °C in temperaturechange) [1.30 ×10−5 (0.000013) in. per inch ofconduitfor each °F in temperature change].

So, in NH when installing HDPE and transition to RGS coming out of a 24" Trench that is in the 54" frost line, is a expansion joint required before entrance to the side of the building?

 

[don_resqcapt19]

In my opinion, 300.5(J), requires the expansion device for that application.

 

[perryalbright]

In my opinion, 300.5(J), requires the expansion device for that application.

So this is an Opinion and not a requirement? I believe it is required, however the reply I was given when I tried to request the Expansion Joints is:

Please refer to Table 352.44With RMC you need to take the length and multiply by .20 IAW 300.7(B) FPN

Informational Note: Table 352.44 and Table 355.44 provide
the expansion information for polyvinyl chloride
(PVC) and for reinforced thermosetting resin conduit
(RTRC), respectively. A nominal number for steel conduit
can be determined by multiplying the expansion length in
Table 352.44 by 0.20. 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)].
A nominal number for aluminum conduit and aluminum
electrical metallic tubing can be determined by multiplying
the expansion length in Table 352.44 by 0.40. The
coefficient of expansion for aluminum electrical metallic
tubing and aluminum rigid metal conduit is 2.34 × 10
−5
(0.0000234 mm per mm of conduit for each °C in temperature
change) [1.30 × 10
−5 (0.000013) in. per inch of conduit
for each °F in temperature change].

The trench is 24" and there is a 90degree sweep of RGS and then one location 4ft up out of the trench and then the other about 6ft. I am getting they do not need it. But I feel that the trench is in the frost line and that there will be frost heaves. So it is not the expansion of the pipe I am concerned about. It is the moving of the HDPE with the 90degree swept with the frost and the HDPE Connection failing.

Has anyone else have a problem like this?

What was the solution?

How do I enforce installation of the expansion joint.

 

[ptonsparky]

Are you writing the specs? Ensuring the job is done as spec'd? Paying the bill?

IMO, that is about all you need, unless the job is done.

 

[Smart $]

...
What was the solution?

How do I enforce installation of the expansion joint.

The only enforceable issue is protection of the conductors within and equipment connected to the raceway from earth or frost movement. 300.5(J) does not specifically mention an expansion fitting. It is but one method used, and quite common I might add... but it is not entirely effective as it does not prevent potential problems resulting from deflection at the horizontal to vertical transition.

 

[don_resqcapt19]

So this is an Opinion and not a requirement? I believe it is required, however the reply I was given when I tried to request the Expansion Joints is:

Please refer to Table 352.44With RMC you need to take the length and multiply by .20 IAW 300.7(B) FPN

Informational Note: Table 352.44 and Table 355.44 provide
the expansion information for polyvinyl chloride
(PVC) and for reinforced thermosetting resin conduit
(RTRC), respectively. A nominal number for steel conduit
can be determined by multiplying the expansion length in
Table 352.44 by 0.20. 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)].
A nominal number for aluminum conduit and aluminum
electrical metallic tubing can be determined by multiplying
the expansion length in Table 352.44 by 0.40. The
coefficient of expansion for aluminum electrical metallic
tubing and aluminum rigid metal conduit is 2.34 × 10
−5
(0.0000234 mm per mm of conduit for each °C in temperature
change) [1.30 × 10
−5 (0.000013) in. per inch of conduit
for each °F in temperature change].

The trench is 24" and there is a 90degree sweep of RGS and then one location 4ft up out of the trench and then the other about 6ft. I am getting they do not need it. But I feel that the trench is in the frost line and that there will be frost heaves. So it is not the expansion of the pipe I am concerned about. It is the moving of the HDPE with the 90degree swept with the frost and the HDPE Connection failing.

Has anyone else have a problem like this?

What was the solution?

How do I enforce installation of the expansion joint.

I agree that you do not need an expansion joint because of thermal expansion and contraction in this application.

You do, however, have to comply with the section I cited. With a conduit system both above and below grade, an expansion joint is the only method of compliance that I am aware of.