Thread: Service Conduit With Expansion Fitting

This is obviously less than 6 feet in lenght. However, it is subject to extreme temperature changes. Do you recommend an expansion fitting. It appears there has been previous movement along the joint.

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I'd look closer at the foundation. From the cracked bricks in the photo it's possibly sheared and the movement caused the conduit to come apart.

If there is no foundation issue I wouldn't recommend a specific repair, but "review and repair by a qualified electrician".

Originally Posted by mathew stouffer

This is obviously less than 6 feet in lenght. However, it is subject to extreme temperature changes. Do you recommend an expansion fitting. It appears there has been previous movement along the joint.

I agree with Ken. The slip fitting is actually more for movement of the ground that the underground SE is in and not for thermal expansion/contraction.

Of much more concern here is whether the wire inside the conduit is being stretched and possibly pulled against hardware in the meter can that will cause a short. Pulling a couple of inches of slack can be a major issue sometimes.

There is no foundation movement. The masonry was loose and missing in areas from poor craftsmanship, but that's it.

Expansion joints/slip fittings are not intended for use in that location, they are for thermal expansion/contraction.

You would NOT want to use one there to allow for soil movement as you would want the conduit to stay put, for the reason Bill gave.

Hang that conduit in place, let the soil move around the conduit, but don't let the conduit move because of the soil, you might just end up with exposed conductors after it mover 'too far'.

The right one is not seated all the way in the top of that coupling, look at that angle.

Missing seal on the power company access cover too.

Originally Posted by Jerry Peck

Expansion joints/slip fittings are not intended for use in that location, they are for thermal expansion/contraction.

I had learned just the opposite. When I lived in MS where we had very expansive soils they required slip fittings midway between SE conduit and the panel or meter.

Is if for the expansion/contraction of the conduit?

Originally Posted by Scott Patterson

I had learned just the opposite. When I lived in MS where we had very expansive soils they required slip fittings midway between SE conduit and the panel or meter.

Is if for the expansion/contraction of the conduit?

Yes, those are for expansion and contraction of the conduit, no way would you want the conduit to rise and fall with the soil, you would want the soil to rise and fall around the conduit.

Otherwise you could very well end up with a slip fitting and conduit being separated and leaving exposed conductors with no protection from physical damage.

Originally Posted by Jerry Peck

Yes, those are for expansion and contraction of the conduit, no way would you want the conduit to rise and fall with the soil, you would want the soil to rise and fall around the conduit.

Otherwise you could very well end up with a slip fitting and conduit being separated and leaving exposed conductors with no protection from physical damage.

Thanks!

So would you want expansion and contraction of the conduit at that joint. The reason I brought it up, is becasue the fitting in the photo is cracked, likely from expansion of the fitting during freeze thraw.

Originally Posted by mathew stouffer

So would you want expansion and contraction of the conduit at that joint. The reason I brought it up, is becasue the fitting in the photo is cracked, likely from expansion of the fitting during freeze thraw.

Mat,

There should not be anything in that conduit which would crack it due to freeze/thaw.

If the freeze/thaw is the soil moving, then the soil should be moving around the pipes.

Hard to tell from the photo, but it looks like that simply was not installed all the way into the coupling, probably because the conduit from above and below are at an angle to each other.

The conduits are there for protection from physical damage, they are presumed to not be water tight, so all conductors in them should be suitably rated for getting wet.

Those should also be Schedule 80 PVC, not Schedule 40, which they probably are, as Schedule 40 is not rated to provide protection from physical damage - Schedule 80 is.

Thanks

In some areas it is common, even required under local rules, to have an expansion fitting where the service exits the ground.

The purpose of this fitting is to allow the conduit to move with the ground, as the annual frost cycle causes the ground to heave.

There is certainly no violation in having such a fitting anywhere- even if it's not needed.