Schedule 80 along residential driveway

[Pierre C Belarge]

This might be a little bit of a thread jack, but it has already been discussed.
Rigid PVC, RMC, RMC - installed on the surface of the ground, secured to the ground by blocks that are driven in the the ground. This would be considered a code compliant installation? Are there any sections in the NEC or the UL White Book that might give guidance to this?



Severe physical damage and physical damage could both mean the same thing. the NEC does not define them... which means someone's opinion could determine either of them to be the same. What I mean is, in one jurisdiction, the AHJ determines the location on the driveway side of the house to be subject to severe physical damage, and in another jurisdiction, the AHJ determined it to be subject to physical damage - who is correct? Both are.

 

[wilsa]

electrician

electrician

when you say along driveway is it undergraund if is it you need to beried at 24 in

 

[mario]

where oh where did sroc go ...

where oh where did sroc go ...

yo sroc ... how about a bit more info as been asked ... can't answer q's like this without ...

 

[iwire]

This might be a little bit of a thread jack, but it has already been discussed.
Rigid PVC, RMC, RMC - installed on the surface of the ground, secured to the ground by blocks that are driven in the the ground. This would be considered a code compliant installation? Are there any sections in the NEC or the UL White Book that might give guidance to this?

Why would we need specific information on that application.

The wiring methods you listed are suitable for aboveground and direct burial. If they are adequately secured what reason could be given to prohibit them from running along the ground?

 

[Pierre C Belarge]

There is an unsual installation request from an EC about installing RMC. They need to install the RMC from a small building along the ground to a cliff and down the cliff face to a small pump house. The "ground" is actually an extremely rocky surface, with the cliff being all rock. The run is about 1200 feet long, 300 feet along the ground, 900 feet down the cliff. This is not an area that sees a lot of people walking around, it is private property (commercial). I have not seen the property, but through hand sketches and phone conversations this is what I have surmised. I told them I would accept the RMC on the surface, but the building department wants it buried or encased in 2 inches of concrete, their contention is the wording in table 300.5.

 

[hardworkingstiff]

...but the building department wants it buried or encased in 2 inches of concrete, their contention is the wording in table 300.5.

If it is buried, then 300.5 applies, but if it is not buried, what would 300.5 have to do with it? I would think the "building" department would defer to you.

 

[hmspe]

The run is about 1200 feet long, 300 feet along the ground, 900 feet down the cliff.

I'd be alot more concerned about the 900' vertical than the horizontal run. Do they have a design for supporting the conductors in the vertical run? Also, are they going to be able to install this without pull boxes on the vertical run? "Accessible" and "800 feet above the ground" don't go together for me. I wouldn't want to be the inspector for the vertical run.

On the surface this project description doesn't make sense. If it's a "small pump house" it won't be pumping up 900'. There has to be an access road to the pump house. Why aren't they running along that road? Securing conduit to the side of a 900' cliff is going to be $$$$$$$. Running a separate service and/or running along an access road could be a lot cheaper than running down the cliff face.

I agree that 300.5 only applies if the conduit is buried. If there's no traffic there's no reason to bury the conduit. I'd draw a parallel to a refinery or similar process plant -- they have conduit on sleepers all over the place.

Martin

 

[Pierre C Belarge]

This cliff is along the water front, there is no road, just water. Yes, this is not great installation conditions, but it is what it is.

I am looking for volunteers for the cliff portion of the inspection...it requires repelling experience - no parachute.
They are using a Bosman's chair for installation (I think that is how it is spelled).
In NYS, the building department is the AHJ. If anyone has pictures of above grade installations of RMC, maybe you can email them to me... the contractor would love to see them.

 

[hmspe]

This cliff is along the water front, there is no road, just water.

Now I'm really curious. They want a pump house in a place with essentially no access except by water. I find it unlikely that the pumps could be pumping up to the top of the cliff because of the head (around 400 psi required to pump water that high in a single stage). To move any significant volume at 400PSI it would be a big pump house. If it involves a pipiline from the top of the cliff to a tank on the bottom the hydraulics would be interesting -- a 1" pipe 900' tall would have an internal volume of arout 8500 cubic inches, or around 37 gallons. That would be hard to control. There's no access to the shore from above if you have to use a bosun's chair or rappel for inspection. What are they pumping? Where does it come from? Where is it going? I'm not a conspiracy theorist, but this seems really, shall we say, unusual.

That said, I'm not sure I could sign off on this as described. It vertical drop would have to have cable supports (you can't free-hang 900' of wire), which means junction boxes to accommodate the cable supports. The j-boxes would have to be accessible. If it requires a bosun's chair I wouldn't say a j-box was accessible. If I was the AHJ I'd be requiring a permanent ladder or stair or something similar to provide access.

I guess the engineer in me is showing....

Martin

 

[iwire]

Not that you did not bring up a lot of interesting questions I am not so sure this is correct.

It vertical drop would have to have cable supports (you can't free-hang 900' of wire), which means junction boxes to accommodate the cable supports. The j-boxes would have to be accessible. If it requires a bosun's chair I wouldn't say a j-box was accessible.

314.29 requires the boxes to be accessible.

Accessible as applied to wiring methods does not prohibit the use of temporary means of access.

This is really no different than a j-box located up on a truss 45' above the floor. You will need some equipment to access the box.

In this case a 'skyhook'

 

[Pierre C Belarge]

The pumps are not pumping up the cliff, but along the cliff. I am not even sure if water is being pumped, I am not sure what is being pumped. The pumps are small, pumping to another building already down there, but remote from the pump. I should have more info soon. But I am not concerned about the item being pumped or the pipes, method, etc... that are being used... I am concerned about the electrical portion of the installation. I forgot to mention the power is coming off of a pole at the street, so a portion of this is actually a service. I am not sure where the disco is, I only saw a hand sketch faxed to me.

Maybe we can make this like the Chesapeak Bay Bridge Tunnel, some undergound, and some above ground... well make bridges and tunnels

 

[paul]

....

In this case a 'skyhook'

I haven't seen one of those since '89.

 

[hardworkingstiff]

In this case a 'skyhook'

Is that kept next to the 'wire stretcher'?

 

[George Stolz]

Pierre, inquiring minds want to know more about this. It's interesting.

I've seen Schedule 80 laying on a hill (with about a 1:1 rise) running up through the woods a hundred feet, secured from side-to-side shifting with rebar at the intervals given for the specific raceway. The RMC and conductors is going to weigh a ton, I don't see how this could be done without some engineering. But I've never contemplated something so different. I suspect that a cordless hammerdrill and little blue anchors are out.

It may seem obvious to some, but I had to go looking to find 300.19 to see how often conductors have to be supported in a vertical run. It's something I'd never really thought about.

 

[hmspe]

The pumps are small, pumping to another building already down there, but remote from the pump.

Back seat drivihg here....

There's no power at the other building? As an electrical engineer I'd be looking at alternate power sources. Maybe a propane genset at the bottom? Maybe photocell? A waterwheel powered by the tide? Pumps powered by the tide? This installation just doesn't seem practical for "small pumps". My guess is at least $50,000 for the install because of the conduit support requirements, crane or scaffold, etc. I can't see this being installed properly by a man in a bosun's chair due to the weight of the components. How do you handle bending the conduit to the contour of the cliff? How do you pull the wire? Using a pneumatic hammer drill on a bosun's chair isn't imnpossible, but it's not easy, and I'm not sure how you'd handle 900' of pneumatic hose.

Maybe this has been thought all the way through -- we only have part of the story. Since safety is the basis for plan review and inspection I see a lot of room for the AHJ to be asking questions. The contractor and owner will also benefit form a very thorough review -- if this got red-tagged the repairs could be difficult and very expensive. If I was the AHJ I'd be looking for plans from a mechanical or civil engineer on how they would support the conduit. The liability exposure here is huge. As George said, the raceway system would be very heavy. If it fell....


Martin

 

[hillbilly]

Is that kept next to the 'wire stretcher'?

I've got to get me one of those. Out here in the sticks, we're a little behind on "new fangled" inventions. The way it is now, I have to carry a bucket of steam around to dip the wire in and make it expand.
steve

 

[jwelectric]

I have sent my new high back bucket seats back for an exchange for a set of wire stretchers and as medium set of sky hooks.

We debated for several days about exchanging the bucket seats for these other items but I finally won out after we had to keep removing the seats in order to take a nap.
see below

 

[hillbilly]

Leroy! You get away from that wheelbarro. You don't know nothing about no "chinery"

 

[celtic]

For Pierre, I'm thinking something in the air as opposed to on the ground for that verical drop....triplex/quadplex would seem to be an easy out???

We "lost" 200' of 4/0 (x4) down an airshaft in a tunnel...was a great "score" for the men, but the brass was not amused.

 

[wireman3736]

I have sent my new high back bucket seats back for an exchange for a set of wire stretchers and as medium set of sky hooks.

We debated for several days about exchanging the bucket seats for these other items but I finally won out after we had to keep removing the seats in order to take a nap.
see below

Looks comfy