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Expansion Fittings #170818 11/12/07 06:13 PM
Joined: Oct 2000
Posts: 3,634
Admin Offline OP
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Quote
This is what happens when the expansion fitting is NOT installed. The side of the box was pulled completely out. These were taken in a parking garage that is being renovated. The metal conduit will probably be replaced by rigid non-metallic conduit sched. 80 WITH expansion fittings.

[Linked Image from electrical-photos.com]

Quote
This is the second of two pictures showing an expansion fitting on rigid conduit. This is how it should be done.

Alan Nadon

[Linked Image from electrical-photos.com]

2017 / 2014 NEC & Related Books and Study Guides
Re: Expansion Fittings [Re: Admin] #170907 11/14/07 06:45 PM
Joined: Mar 2004
Posts: 391
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BigJohn Offline
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I understand the reason for expansion fittings, but never really saw an install where I was thinking "They'd really be up a creek if they hadn't put that expansion coupling in." Now here's a dramatic example of what happens when you don't. Neat.

-John

Re: Expansion Fittings [Re: BigJohn] #170918 11/14/07 11:44 PM
Joined: Oct 2007
Posts: 56
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SP4RX Offline
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Wow.

Is expansion/contraction really what caused that?? I never would have guessed that a lack of provision for expansion could result in something this dramatic.

Kinda makes me ponder the 250 feet or so of EMT I just ran the other day...oh wait, that was inside a heated building. *whew*


Shawn.

Re: Expansion Fittings [Re: SP4RX] #170956 11/15/07 07:42 PM
Joined: Aug 2002
Posts: 402
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jdevlin Offline
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That must have been some long conduit run to expand/shrink what looks like 2 inches. Are you sure it is not from damage further down the conduit run?

Re: Expansion Fittings [Re: jdevlin] #170970 11/16/07 12:06 AM
Joined: Feb 2004
Posts: 1,437
Lostazhell Offline
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There's a run of 3/4 galvanized that runs along a fenceline for about 1200 feet out where I work (For H2S monitors) In the cold, it's straight as an arrow, but once it gets above about 80F or so... It starts doing the wave... along the WHOLE run!

Re: Expansion Fittings [Re: Lostazhell] #171132 11/20/07 12:43 PM
Joined: Mar 2005
Posts: 1,213
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SteveFehr Offline
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The coefficient of thermal expansion for steel is 0.00000645in/in/deg. Doesn't sound like much, but for a 100' piece of pipe, the difference between a -20F day and a 110F day is 1". Aluminum expands twice as much as steel. Concrete is practically identical to steel. (Convenient for rebar, eh?) BUT, if that concrete has expansion joints, and the steel doesn't...

PVC is far worse, as it has a much higher coefficient of expansion. A similar piece of RNC would have an appx 4.5" expansion/contraction.

Last edited by SteveFehr; 11/20/07 12:45 PM.
Re: Expansion Fittings [Re: SteveFehr] #182701 12/07/08 12:39 AM
Joined: Mar 2008
Posts: 144
JoeKP Offline
Member
look @ how bent up it is, i don't think an expansion fitting would of helped that


-Joe
“then we'll glue em' then screw em'”
-Tom Silva
TOH

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