What do you guys think of the new PVC risers for underground services?(at least they are new here)

Obsaleet

I'm curious too. I don't do many UG services so I'd like to know what a PVC riser is in the first place.

Is this riser similiar to an expansion coupling?

Sched 80 PVC risors have been the norm for UG services around here for 25 years.

Rigid aluminum risers were used here until the late 1980's but since then, it's been 2" PVC, furnished and installed by the power company. They also require that the connection be threaded (via hub), not lock nuts, but they do that part anyway. They supply and bury their own 1/0 aluminum triplex buried service lateral for anything up to 300 amps for residential.

For risers on poles, same applies, except they use 4" PVC cable guard ("U" guard) up the pole.

[This message has been edited by EV607797 (edited 12-23-2006).]

In my opinion PVC has no place being used as a riser unless it is than guarded by steel. I live in an area that gets cold. Combine cold with aged brittle PVC and you get something that breaks easily.


It is the part of an underground service raceway that breaks the surface of the ground and runs up the utility pole or building.

Here in Minnesota we use Sch 80 as the norm.
Sure I have seen broken pvc, But I dont think rigid steel would of help in most cases. something else would of broke instead or been bent or sqaushed.
Every job has differant set of differances and all materials have a place. The side of a house and a alley are two differant types of areas and I would use the rigid in the alley.

[This message has been edited by john p (edited 12-21-2006).]

Schedule 80 is commonly used here for running underground feeders from a pole mounted transformer. Lots of the cities that were originally built with service drops from poles are now requiring all new construction to run their new service feeders underground from these same poles (except in completely new communities, where the service network is already planned as an underground installation). I'm assuming this is in the interest of beautification.

Our job is to trench to the pole (from our new service) and install the PVC run up to the pole (with just enough SCH 80 popping out of the ground for them to couple to). The PoCo then installs the ladder jacks on the pole and the SCH 80 for the first 10 feet or so, then usually (but not always) SCH 40 the rest of the way up to the transformer.

Although this PVC may seem like a bad idea on paper, I've actually seen very, very few problems as a result of this type of installation. In an area with freezing temperatures, however, I could not venture a guess as to the durability of the PVC. I've seen impact from cars, and usually the pole takes most of the beating, where as the PVC will usually either dent or just crack. I've yet to see it break away and leave the feeders exposed.

Personally, I have no problem with it at all. If the PoCo wants it, then the PoCo gets it, and we have little choice in the matter.

Check out this link and tell me PVC risers are better!!

Caution to dial-up users: this is an 8 minute video.

Fred,
It is now a requirment here. My question is when the conduit drops the joint slides down, what happens to the conductors? They can't move there tied to the lugs.

http://www.carlon.com/sd-cgi/hsrun....LONTemplateDisplay.run?CatalogObjectId=1 52

[This message has been edited by Obsaleet (edited 12-21-2006).]

Can't seem to get the link to work but look for slip risers under electrical. to have a look at one
Ob

When they first went to PVC risors for UG around here both PoCos required a 90 deg sweep 24" below grade. When it became obvious that over time the ground settling around the 90 pulled down on the pipe and caused damage, they prohibited the use of the 90 and instead required just a straight pipe at least 24" below grade with a slack loop of conductor where it entered the risor.

They are not legal here. We do a GRC 90 up, then GRC up the pole.

IMHO (stress the H) a riser should be GRC.

We run 3" pvc from transformer/pole to meter socket with this thing at the riser. They were having guys not straping well and then not back filling right. The meter sockets would pull right off the building. Now we have These things, but there is no place to leave slack for the cable?

Ob

mxslick,
While I am not a fan of PVC because of the physical damage issue, I watched the same thing happen to a 4" rigid steel riser with 4 500 kcmil conductors. Both the conduit and the conductors "vaporized".
Don


[This message has been edited by resqcapt19 (edited 12-23-2006).]

There are some areas along the coast where PVC is used but its more an issue with the GRC not lasting long in the salt air.

I share your opinion on the physical damage issue, especially since PVC is much more likely to get damaged by a "love tap" from a passing truck than rigid steel. I'm almost willing to bet that a tap from a truck is waht started the fault in the video.

But to be fair, I will concede that nothing is gonna stop a fault on a POCO feed from burning through whatever pipe it may be in. Unless through dumb luck the transformer's primary fuse is either weak or was sized to open under a secondary fault.