Use of expansion joint with 2" PVC overhead service

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peter d said:
PVC, just like SE cable, gets brittle from sunlight over time.



I get them too, just last week I had to temporarily repair a panel with water damage getting in through the cable. It doesn't stop me from using it. Water entry is due to poor installation practice. There are products that need to be used correctly so that doesn't happen. The primary reason why water gets into the panel with SE cable is because of hack electricians who use duct seal on top of the so-called water tight connector on top of the meter socket, and where the cable enters the house, and/or leave too much neutral conductor exposed where it enters the weatherhead. The duct seal dries out and you end up with water in the panel and meter socket. I use silicone or phenoseal to solve those problems.
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The sun kills them both and dis colors them as well. My thoughts are the PVC will discolor and get brittle but it will still be more water tight than the SE. On the SE once the jacket gets any cracks it just runs water into the meter, then to the panel.
One thing I get a lot are broken expansion clips on the PVC so nothing is lifetime anymore.
 
It seems that most of the deteriorated cables I'm finding are on the side of the house exposed to the sun (PA). Also, some look like the cable was painted, perhaps drying out the insulation. Years ago, I used a neoprene cable a couple times, though more expensive, they seem to hold up better. The use of PVC to me is easier, last longer, and I can use copper conductors. I really appreciate the input and opinions, since I really haven't decided what I am going to do.

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dielectricunion said:
Even if it's allowed there for service raceway, it has to be min 2" rigid if it's being used as support for the overhead conductors (I'm sure everyone already knows this, just figured I'd mention it)


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I'm sure if he is replacing what was otherwise going to be SE cable with the PVC neither was going to end up supporting the overhead conducors.;)

dannolf@yahoo.com said:
I was using shallow strut to space it off the wall.I could make the clamps semi tight but the 2 hole straps are better. I guess your implying that the expansion of the PVC is minimal and there is room to expand. Thanks

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You can spend money on expansions if you want, there is no code violation if you use them where not otherwise required.

If you only go a few feet then have an elbow that is not firmly secured you have room for deflection of that elbow to allow the expansion without possibly damaging the raceway.

The requirement for an expansion fitting is where the temperature change is enough to allow more then a 1/4 inch change in length of the PVC conduit and there is fixed supports or termination points at each end. In that case it has no where to go and something will be strained and possibly broken when temperature changes occur. Secure clamping doesn't allow the pipe to move when it expands.

I believe there are strut clamps designed for PVC, though I have never used them. Another option may be to put a sleeve of metal pipe that allows the PVC to slip through it around your PVC and clamp that into an appropriately sized strut clamp, if you are set on using strut.
 
JoeyD74 said:
The sun kills them both and dis colors them as well. My thoughts are the PVC will discolor and get brittle but it will still be more water tight than the SE. On the SE once the jacket gets any cracks it just runs water into the meter, then to the panel.
One thing I get a lot are broken expansion clips on the PVC so nothing is lifetime anymore.
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I'm well aware of the shortcomings of SE cable, but again, it's not going to stop me and many other electricians in my state from using it. I know I sound like a broken record but I'm just not seeing a lot of cracked SE cable unless it's the old cloth stuff. Yes, of course I have seen and replaced cracked cables but it's just not this common problem that some are making it out to be.
 
1964element said:
Steel doesn't move and the sun doesn't eat it
Unicorns are know to stay away from it.

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Steel does move, but at a much lower rate per degree of temperature change then PVC. The rate is low enough we don't have to concern ourselves with it very often in this trade.
 
This particular problem happened on a job in which I installed a larger panel on an existing service. The cable looked fine on the outside from the ground, so I just changed the panel. 2 years later, I went back to do some other work and saw the bottom of the panel was rusted severely an the service terminations were so corroded I couldn't loosen them. I got a ext. ladder out and discovered the top of the cable running up the side of the house at an angle was split wide open for about 10'. After visiting the Conn. shore and seeing all the PVC services, I am contemplating using PVC.

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dannolf@yahoo.com said:
This particular problem happened on a job in which I installed a larger panel on an existing service. The cable looked fine on the outside from the ground, so I just changed the panel. 2 years later, I went back to do some other work and saw the bottom of the panel was rusted severely an the service terminations were so corroded I couldn't loosen them. I got a ext. ladder out and discovered the top of the cable running up the side of the house at an angle was split wide open for about 10'. After visiting the Conn. shore and seeing all the PVC services, I am contemplating using PVC.

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Raceways still get moisture inside because of condensation and still will lead to some of the issues you are trying to avoid. Paying attention to this and routing things so that drainage goes to more desirable areas does give you some improvement. I don't like how many loadcenters and disconnects typically have top entry hub directly over top of main lugs/main breaker as this invites any drainage from the top entry to run right into those terminations. Meter sockets are not as bad other then the neutral lug is usually straight below the entry.
 
Of course, rigid is the best, but harder to work with. I just think PVC is better than SE cable. Using an expansion fitting wouldn't hurt. Strut is nice to space off surface differences. Support hardware type and usage is very important, the main reason I'm looking for opinions. Also, I always take into account, the code book is minimum and maximum requirements.

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