Conduit on Jersey Barriers?

[TwoBlocked]

Am scheduled to do the control terminations on a site where some PVC conduits will be mounted on a jersey barrier fence about 1000 ft long. There will be expansion joints in the install. Never heard of this before, but there's plenty I never heard of. Anybody got experience with this?

 

[Shaneyj]

No experience actually mounting conduit as you say but I’ve been involved with projects where Jersey barriers are used to protect MV and LV cables running through the dirt (oilfield)
From a logic standpoint, those barriers are stout. I wouldn’t have a problem using it as mounting structure if that’s what customer requested.


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[tom baker]

If the PVC was on the side away from traffic, its protected somewhat. But 1,000 feet will require multiple expansion couplings, and the PVC has to be fastened closer than the NEC allows to prevent sagging. Jersey barriers have wire loops on the ends and use a large pin to couple together (the ones here do)Does the pin go into the ground, or will the jersey barrier defect if hit?
IMO PVC run horizontally on a building always sags and looks like a DIY job. RMC would be faster to install using 1 hole mallable straps and zamac anchors. PVC would have to be held level before fastening, and the PVC straps have to allow for movement for the expansion to go to the coupling
If possible please post back how many expansion couplings are required for 1,000 ft, but perhaps its 1,000 ft barrier with PVC on part of it
Also at 1,000 ft RMC may require an expansion coupling.

 

[letgomywago]

If the PVC was on the side away from traffic, its protected somewhat. But 1,000 feet will require multiple expansion couplings, and the PVC has to be fastened closer than the NEC allows to prevent sagging. Jersey barriers have wire loops on the ends and use a large pin to couple together (the ones here do)Does the pin go into the ground, or will the jersey barrier defect if hit?
IMO PVC run horizontally on a building always sags and looks like a DIY job. RMC would be faster to install using 1 hole mallable straps and zamac anchors. PVC would have to be held level before fastening, and the PVC straps have to allow for movement for the expansion to go to the coupling
If possible please post back how many expansion couplings are required for 1,000 ft, but perhaps its 1,000 ft barrier with PVC on part of it
Also at 1,000 ft RMC may require an expansion coupling.

Cost wise right now smaller size rmc isn't even that big of a material price increase vs pvc.

 

[tom baker]

PVC jacketed MC is a good option. , unroll and strap, but OP did not mention if this is for power or controls, by controls I mean would it be available in P coated MC?

 

[TwoBlocked]

Thanks, guys. The whole thing is a mash-up. Fortunately or otherwise, I may or may not have responsibility for much of what's going on. Got a set of drawings that are like a jigsaw puzzle with pieces missing. Starting my second week on the job and am their first electrician east of the Mississippi. There's at least 5 major entities involved.

Not quite sure, but am thinking that the jersey barriers are the walls for a secondary water containment that is lined with rubber sheeting and the conduits will be run on the outside of the containment - I think. I get the idea that decisions were made by novices with big pockets saying "Hey, we could do this! Ain't we smart?"

Some of the conduits are for control and communication, and one is for power. Now get this: After going thru the sketchy drawings and schedules, they are feeding one 100A panelboard from another 100A panelboard from 2000 feet away. The schedule shows five 350 MCMs in a 4" conduit mounted on these jersey barriers, but partly underground, too. (I think...) When you do the math for voltage drop I can see why. Voltage is 120/240. But when you look at the bigger picture, there are other possibilities. The load is only 25A, yet the schedule shows the sub panel being fed from a 20A breaker in the main panel. Obviously an oversight easily fixed with a bigger breaker. But the loads themselves are not voltage sensitive being 24V power supplies and heat trace. Hopefully the power contractor knows to install 30mA GFIC breakers. Regardless, some distribution blocks will be needed - no mention of them on the drawings.

I won't be working on the installation of the power part, but will still be involved on making this work. I'll be working on the control part and there are many more and different kinds of conductors needed that what is shown on the schedules. Should find out this week how far along the project is and how and what might be able to be changed.

I can see the jersey barrier idea working as long as they are sitting on stable fill. But just one soft spot with freeze and thaw will result in busted conduit. The conduit is on the western and southern exposures, too.

 

[zbang]

novices with big pockets saying "Hey, we could do this! Ain't we smart?"

The same ones who didn't think, "Hey, maybe we could send 480 volts instead of 240, cut the losses, and use much less wire?"

IIRC often the concrete used in Jersey walls is much harder* than the usual pour-in-place construction stuff; be prepared for Hilti shots to bounce and for trouble drilling. Not always, but it can happen.

*factory-cast concrete can be much better controlled than ready-mix, which has to stay liquid for a couple of hours, and more controlled curing (and age). I saw some that was mix-pour-hard in maybe an hour.

 

[drcampbell]

... just one soft spot with freeze and thaw will result in busted conduit. ...

That was my first thought. Freeze-thaw heaves are an obvious concern in Pennsylvania, and if the "structure" is being built with Jersey barriers, expecting a solid, stable foundation seems a trifle unwarranted.

Is this a temporary installation? A generally-unoccupied location? An above-ground waste pit? Do appearances matter? Maybe conduit isn't required at all and the whole thing could be wired with SO cord. It would certainly eliminate any concerns with expansion joints and breakage.

 

[Shaneyj]

That was my first thought. Freeze-thaw heaves are an obvious concern in Pennsylvania, and if the "structure" is being built with Jersey barriers, expecting a solid, stable foundation seems a trifle unwarranted.

Is this a temporary installation? A generally-unoccupied location? An above-ground waste pit? Do appearances matter? Maybe conduit isn't required at all and the whole thing could be wired with SO cord. It would certainly eliminate any concerns with expansion joints and breakage.

Based on OP “fracking” comment I figured holding pit for flowback or spent frack mud/fluid.


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[petersonra]

Why not EMT? RMC seems like crazy overkill and outdoor PVC always seems to sag.

Personally, I like the idea someone else suggested of MC. No matter what you do it is going to look a little strange, so appearance is not an issue.

 

[TwoBlocked]

Apparently this is somewhat common in the gas industry. A drawback is the concrete anchors sometimes let loose allowing the PVC conduit to flap in the breeze.