Expansion joints.

jwprzybyla

Member
Location
California
Occupation
PM
Howdy!
We are experiencing some conduit separation and need to install some expansion joints, the issue is we have already pulled wire through and are trying to avoid having to pull the wire out to install the expansion joints. Does any one know of maybe an expansion clamp that can be placed over the conduit? Something that maybe comes in two halves that can be placed over the conduit and secured? Just trying to avoid all the work it will take to pull the wire out of the conduit.
Many thanks!
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
Google may be your friend. Best result that comes up is at ET. https://www.electriciantalk.com/thr...-joints-after-pipes-already-installed.289050/

The one possible solution which may or may not work for you, depending on what the enviroment is where you need to install the joint and whether there is enough slack in the conductors to accomodate:
Maybe you could avoid pulling out the wire if you cut out the back to back 90s with string, then split the conduit with an oscillating tool. Then cut the wires, install a junction box with expansion fittings on either side, and splice the wires.

Ignore the back to back 90s reference. That was an attempt to avoid placing a needed expansion joint during initial installation.
On the other hand, that detail may have been necessary to provide enough slack in the wires.
Instead you might put in a large enough box to splice in an extra segment of wire for each feed through.
Seems really kludgy, but....

Another approach would be to place two splice boxes and expansion joints an appropriate distance apart and repull just the wires joining the two boxes.
 
Last edited:

synchro

Senior Member
Location
Chicago, IL
Occupation
EE
How are the conduits supported? Is there a way to modify it to minimize the stress from expansion/contraction while still meeting code requirements?

The clamp from Carlon at the link below claims:
"This high strength, nonmetallic clamp allows conduit to expand and contract freely, eliminating the bowing commonly seen from the expansion and contraction of conduit caused by varying temperature changes."
I have no experience with it and so I don't know how well it works.

https://carlonsales.com/supportstrapsclamps.php
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
How are the conduits supported? Is there a way to modify it to minimize the stress from expansion/contraction while still meeting code requirements?

The clamp from Carlon at the link below claims:
"This high strength, nonmetallic clamp allows conduit to expand and contract freely, eliminating the bowing commonly seen from the expansion and contraction of conduit caused by varying temperature changes."
I have no experience with it and so I don't know how well it works.

https://carlonsales.com/supportstrapsclamps.php
It only works when the conduit would be free to take up expansion from joints or long 90 degree section if the clamp were not constraining it. You are always required to use clamps that allow the conduit to slip, so this is nothing magical.
 
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