How To Install Pvc Expansion Coupling

Expansion

Joints for PVC

Rigid Nonmetallic

Conduit

All structure materials expand and contract
with fluctuations in temperature. These temperature
changes bear upon polyvinyl chloride (PVC) more than
traditional materials such as aluminum and steel. For
example, the coefficient of thermal expansion for PVC
(3.38 10 10

-five

in./in./°F) is near three times as high as

for aluminum and six times as loftier as for steel.

Thermal expansion and contraction accept a meaning
effect on long straight runs of conduit. For this

application, expansion joints are used to accommodate changes in length. This prevents potentially
harmful thermal stresses in the conduit itself or in any supporting structures.

Expansion Fittings Required

Section 347-9 of the National Electrical Code

®

requires that expansion joints be installed for rigid

nonmetallic conduit to compensate for thermal expansion and wrinkle where the length change
is anticipated to be 0.25 in. (6.36mm) or greater, in accordance with Table 347-9 of the 1999 NEC, in
a direct run between securely mounted items. Deeply mounted items are boxes, cabinets, elbows,
or other conduit terminations.

When are expansion joints used?

The importance of knowing when to employ an expansion joint is equally of import as knowing how to use
an expansion joint. Expansion joints are used in aboveground installations where temperature
changes are anticipated to exceed 25°F (14°C).

Expansion joints are usually used where the
directly run length is greater than 25 feet and
expected temperature alter is greater than
lx°F. Rigid PVC conduit has a coefficient of
expansion of 3.38 x 10

-v

in./in./°F. A 10 foot

length will alter in length nigh

three

/

8

" with a

change in temperature of 100°F. This equates
to more than 4 inches over a 100 foot run.

Barrel

Cage

Piston

Gross Automation (877) 268-3700 · www.carlonsales.com · sales@grossautomation.com

Source: https://www.manualsdir.com/manuals/321621/carlon-expansion-joints-for-pvc-rigid-nonmetallic-conduit.html

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