Conduit Underground

[Duuuuug]

Table 300-5 Column 3
A contractor installed a two inch PVC/Sched.40 conduit (direct buried) to get 480/3PH power to a small (2-10HP pumps) waste water pump station located 500FT from a school's panel board. The conduit is 24" below grade. The conduit extends from the school, under a parking lot and then under a soccer field to the pump station.

1. As long as the conduit is rated for direct burial and it is 24" below grade, this complies with NEC. Correct?
2. Does anyone have a way to permanently mark the path of the conduit?
I just have heart burn about the possibility of someone digging and hitting the conduit in the future.

 

[petersonra]

Re: Conduit Underground

burying it underground is probably the safest place to put it.

 

[bphgravity]

Re: Conduit Underground

1. yes

2. Mark the conduit run on a set of plans. Include dimensions and measurements so it can be located in the future.

Person in the future will have to use due caution. It would have been advisiable to place warning tape in the trench above the conduit runs, though not required by the code.

 

[wbalsam1]

Re: Conduit Underground

As pertaining to warning ribbon, would NFPA 70-2005 300.5 (D)(3) apply for conductors in conduit or just conductors direct buried?

[ July 27, 2005, 04:39 PM: Message edited by: wbalsam1 ]

 

[infinity]

Re: Conduit Underground

As pertaining to warning ribbon, would NFPA 70-2005 300.5 (D)(3) apply for conductors in conduit or just conductors direct buried?

Both, as long as they're service conductors.

 

[benaround]

Re: Conduit Underground

Duuuuuug,

Rolaid's work pretty good!

frank

 

[benaround]

Re: Conduit Underground

Duuuuuug,

Rolaid's work pretty good!

frank

 

[tx2step]

Re: Conduit Underground

The best warning tape to use has a metal backing that can be picked up with a detector. It's a lot more expensive, but you can find it before you dig.

On some military work, I have also installed concrete markers along the path of the ug ducts. These were 4"X4"X12" (like a short post) with a #3 rebar in the center. I stamped an arrow into the top of the concrete post indicating the direction of the run, and also chamfered the edges of the top. These were buried with the top about 1/2" above grade every 50' along the run. I also placed one at each change of direction, with a bent arrow indicating the direction change. Very effective and easy to make. I made the forms out of plywood and used sackcrete. A little time consuming, but not too bad if you make just a few a day over several days. I made about 6 per day.

I'd make some and install them before your trenchline fades out. Put one at each edge of the parking lot, too.

Edited to add: I buried the markers directly over the ducts. The more of them that you install, the easier it will be to follow the run.

[ July 27, 2005, 07:56 PM: Message edited by: tx2step ]

 

[tom baker]

Re: Conduit Underground

If there is a conductor in the UG conduit, then you don't need detecable warning tape. A UG locator can induce a signal in the run and it can be easily located.
I don't put a lot of trust in any UG warning tape.
I would rather have a bed of sand around the conduit , then if you are digging you'll know when your are close.
The UG locators, are very accurate and can be within inches. 3m makes little balls that can be buried and then work with a radar type detector. But everyone I have seen uses a UG locator that detects a signal induced or direct (de-energized) onto a conductor.
Witching works pretty well, I have found.

 

[mdshunk]

Re: Conduit Underground

Originally posted by tom baker:

Witching works pretty well, I have found.

Can you explain how you go about this process? I'm not ruling anything out, but I automatically put this up there with astrology and palm reading for some reason.

 

[Duuuuug]

Re: Conduit Underground

I want to thank everyone for their input.
As always, your time and suggestions are very much appreciated.
Doug
Rolaids.....you kill me!