# Expansion coupling for rigid



## rrb8705 (Oct 29, 2013)

When doing a service upgrade and Meter replacement is it necessary to put a type of expansion coupling if The feeder going up into the meter is rigid pipe? I know it's necessary for a PVC feeder but rigid? The house is in Colorado built in 1972. There did not appear to be any strain or stress on the existing feeder pipe at the meter connection.


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## aftershockews (Dec 22, 2012)

From what I can see in the NEC, expansion fittings are mostly if only required for non metallic conduit. I may have missed something though.

EDIT:
I see now you specified rigid which could also mean PVC.



> 378.44 Expansion Fittings. Expansion fittings for nonmetallic
> wireway shall be provided to compensate for thermal
> expansion and contraction where the length change is expected
> to be 6 mm (0.25 in.) or greater in a straight run


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## aftershockews (Dec 22, 2012)

I always thought the need would only come up if the raceway was terminated between 2 boxes and not on something like a riser.


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## rrb8705 (Oct 29, 2013)

RMC


But that was my thinking too, just psyching myself out trying to think of anything else the inspector could possibly nab me for.


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## aftershockews (Dec 22, 2012)

rrb8705 said:


> RMC
> 
> 
> But that was my thinking too, just psyching myself out trying to think of anything else the inspector could possibly nab me for.


If it is RMC don't sweat it. Your good.


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## rrb8705 (Oct 29, 2013)

aftershockews said:


> If it is RMC don't sweat it. Your good.


That's kind of what I thinking in the first place. Thanks for the help sir.


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## 99cents (Aug 20, 2012)

Is this an underground service? If so, why are you using rigid steel?


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## rrb8705 (Oct 29, 2013)

99cents said:


> Is this an underground service? If so, why are you using rigid steel?


It's existing. My guess is it transitions to PVC underground.


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## wcord (Jan 23, 2011)

rrb8705 said:


> It's existing. My guess is it transitions to PVC underground.


I've run into a few services for houses built in the 70s, which had buried RMC.


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## Southeast Power (Jan 18, 2009)

rrb8705 said:


> When doing a service upgrade and Meter replacement is it necessary to put a type of expansion coupling if The feeder going up into the meter is rigid pipe? I know it's necessary for a PVC feeder but rigid? The house is in Colorado built in 1972. There did not appear to be any strain or stress on the existing feeder pipe at the meter connection.


Be aware that the house will settle differently than the rigid coming into the underground.
Strap the conduit to the house in at least to places. Code might require one, I would go with two very tight straps.


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## LGLS (Nov 10, 2007)

jrannis said:


> Be aware that the house will settle differently than the rigid coming into the underground.
> Strap the conduit to the house in at least to places. Code might require one, I would go with two very tight straps.


I would think that since 1972 the house has settled all it's ever going to.

In fact, do houses really ever "settle" at all? Houses are built on foundations that are on footings for the expressed purpose of NOT moving at all, ever.


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## rrb8705 (Oct 29, 2013)

IslandGuy said:


> I would think that since 1972 the house has settled all it's ever going to.
> 
> In fact, do houses really ever "settle" at all? Houses are built on foundations that are on footings for the expressed purpose of NOT moving at all, ever.


Yea but the dirt around them that contains the Condit will settle and move up/down. But yes, Foundations do move and even crack if they aren't built properly or if The soil is really nasty.


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## sbrn33 (Mar 15, 2007)

It is not the house that settles it is the underground wiring that was not installed correctly. Or the concrete slab that people pour around it that settles and pulls the SE conductors out of the socket.


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## aftershockews (Dec 22, 2012)

wcord said:


> I've run into a few services for houses built in the 70s, which had buried RMC.


Same here. On duplexes. A lot have the 2 bank socket pulled away from the wall.


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## Southeast Power (Jan 18, 2009)

IslandGuy said:


> I would think that since 1972 the house has settled all it's ever going to.
> 
> In fact, do houses really ever "settle" at all? Houses are built on foundations that are on footings for the expressed purpose of NOT moving at all, ever.


I thought about how rare that is after I posted that comment.
I have maybe only seen a few but one that comes to mind is one where the house was in a coastal area, even built on pilings and the conduit entering the meter can settled about 4" more than the house. It was just about an inch from the bottom lugs. I had to dig it out and hammer it back down.


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## don_resqcapt19 (Jul 18, 2010)

If this is an underground service 300.5(J) applies no matter what type of raceway is used. Many AHJs read this section as requiring an expansion fitting.


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## Awg-Dawg (Jan 23, 2007)

don_resqcapt19 said:


> If this is an underground service 300.5(J) applies no matter what type of raceway is used. Many AHJs read this section as requiring an expansion fitting.


 I don't think Ive ever seen one for RMC, other than what is used on expansion joints in buildings.

Is there another type?


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## rrb8705 (Oct 29, 2013)

Awg-Dawg said:


> I don't think Ive ever seen one for RMC, other than what is used on expansion joints in buildings.
> 
> Is there another type?


I had to look it up, never see this before though.

http://www.cooperindustries.com/con...series_conduitexpansionjointsforrigidimc.html


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## Awg-Dawg (Jan 23, 2007)

rrb8705 said:


> I had to look it up, never see this before though.
> 
> http://www.cooperindustries.com/con...series_conduitexpansionjointsforrigidimc.html


 
That looks expensive.

Here is the article Don was citing.

I actually never gave RMC a thought before till now, I probably wouldn't put in tho (Ive never seen it enforced here)

But, It wouldn't be a bad idea to run thru your inspector.(Your luck he would read it and make you do it):laughing:


* (J) Earth Movement.​*​​​​Where direct-buried conductors,​
raceways, or cables are subject to movement by settlement​ or frost, direct-buried conductors, raceways, or cables shall​ be arranged so as to prevent damage to the enclosed conductors​ or to equipment connected to the raceways


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