Underground UF Installation

[shortcircuit2]

The GC on a dwelling remodel wants to install post lights for the owner along his 300 ft driveway, but doesn't want to dig a trench to lay the UF wire.

He wants to lay irrigation pipe down (12inches) with the trenching machine the landscapers use and then snake the UF wire through.

I told him I would not put my name on the job...because the pipe is not approved for electrical installations.

Has anyone ever done post lights this way? Is there an approved conduit that can be installed with one of these ditching machines?

shortcircuit2

 

[iwire]

Re: Underground UF Installation

IMO You do not need a listed raceway to contain a listed cable assembly.

A stud bay in a home is not a listed raceway and you install NM in that space.

That said IMO it still would have to meet the depth requirements for UF. 12" would require GFCI protection.

 

[pierre]

Re: Underground UF Installation

Take a look at Art 354 (NUCC)
I am not too familiar with this method, and it may be hard to find. There are other methods of burying pipe and then installing the conductors. It is good that you will not lower yourself to this contractors low standards.

 

[pierre]

Re: Underground UF Installation

If one is to try and use a pipe or conduit that is not listed to contain wiring, such as plumbing pipe, you would not be following the proper use of the pipe. Plumbing pipe is listed as suitable for the purpose of "plumbing", not wiring. 110.3(B)

 

[iwire]

Re: Underground UF Installation

Originally posted by pierre:
If one is to try and use a pipe or conduit that is not listed to contain wiring, such as plumbing pipe, you would not be following the proper use of the pipe. Plumbing pipe is listed as suitable for the purpose of "plumbing", not wiring. 110.3(B)

Pierre, cable assemblies do not require a listed raceway.

By the way 110.3(B) can not apply to the plumbing pipe as it is not under the scope of the NEC.

Now try installing THWN in plumbing pipe and I would agree with you whole heartedly. There are rules against that.

334.15(B) Protection from Physical Damage. The cable shall be protected from physical damage where necessary by conduit, electrical metallic tubing, Schedule 80 PVC rigid nonmetallic conduit, pipe, guard strips, listed surface metal or nonmetallic raceway, or other means.

Other means are just that, other means, as in other than the means listed.

This is not 'pushing' the code.

It seem ludicrous to me that some one would accept UF direct buried but would refuse it if protected by a plastic tube.

Can anyone explain the common sense there?

 

[pierre]

Re: Underground UF Installation

From Bob
"Can anyone explain the common sense there?"

Common sense???? Bob were electricians, common sense, ha ha

 

[iwire]

Re: Underground UF Installation

Originally posted by pierre:
From Bob
"Can anyone explain the common sense there?"

Common sense???? Bob were electricians, common sense, ha ha

Well I would like to think we still have some.

 

[George Stolz]

Re: Underground UF Installation

Originally posted by pierre:
Plumbing pipe is listed as suitable for the purpose of "plumbing", not wiring. 110.3(B)

Where do I find dirt in the white book, Pierre?

(Looking back at that question, I'd imagine it would be very easy to spot dirt in a white book. )

The unlisted pipe is replacing unlisted dirt, it's not being used as a listed raceway.

 

[jwelectric]

Re: Underground UF Installation

I have lived through a debate similar to this one before and I am sorry to inform you that it is illegal to install UF cable in any other raceway than one that is listed for the purpose.

Originally posted by Iwire
quote:

334.15(B) Protection from Physical Damage. The cable shall be protected from physical damage where necessary by conduit, electrical metallic tubing, Schedule 80 PVC rigid nonmetallic conduit, pipe, guard strips, listed surface metal or nonmetallic raceway, or other means.

Other means are just that, other means, as in other than the means listed.

This is not 'pushing' the code.

It seem ludicrous to me that some one would accept UF direct buried but would refuse it if protected by a plastic tube.

Can anyone explain the common sense there?

There was a change in the 2005 cycle to 334.15 which now states;

(B) Protection from Physical Damage. Cable shall be protected from physical damage where necessary by rigid metal conduit, intermediate metal conduit, electrical metallic tubing, Schedule 80 PVC rigid nonmetallic conduit, or other approved means. Where passing through a floor, the cable shall be enclosed in rigid metal conduit, intermediate metal conduit, electrical metallic tubing, Schedule 80 PVC rigid nonmetallic conduit, or other approved means extending at least 150 mm (6 in.) above the floor.

Now at the risk of starting an argument 334 does not apply to UF unless it is being installed on the inside in the place of NM-B

Looking at 340;

340.10 (1) For use underground, including direct burial in the earth. For underground requirements, see 300.5.

300.5 Underground Installations.
(A) Minimum Cover Requirements. Direct-buried cable or conduit or other raceways shall be installed to meet the minimum cover requirements of Table 300.5.

As I look at the table I find five columns, Column 1 Direct Burial Cables, Column 2 Rigid Metal Conduit or Intermediate Metal Conduit, Column 3 Nonmetallic Raceways Listed for Direct Burial Without Concrete Encasement or Other Approved Raceways, Column 4 Residential Branch Circuits Rated 120 Volts or Less with GFCI Protection and Maximum Overcurrent Protection of 20 Amperes, Column 5
Circuits for Control of Irrigation and Landscape Lighting Limited to Not More Than 30 Volts and Installed with Type UF or in Other Identified Cable or Raceway.

Now in column 3 I see ?or other approved raceways? which would leave the approval in the hands of the code enforcement official except in states that have adopted a law similar to this.

In summary, no you cannot use anything other than a listed raceway system for the installation of UF cable underground in North Carolina.

 

[infinity]

Re: Underground UF Installation

IMO You do not need a listed raceway to contain a listed cable assembly.

A stud bay in a home is not a listed raceway and you install NM in that space.

I'm with Bob. Plastic pipe is not a raceway and a UF cable is not single conductors that are typically installed in raceways. Since in this case the pipe would only be providing more protection than the dirt I see no problem with it, providing that the proper burial depth for type UF cable is maintained.

 

[jwelectric]

Re: Underground UF Installation

Are we saying that this installation would comply? These conductors are approved for direct burial.

 

[allenwayne]

Re: Underground UF Installation

Ok so the C.M. wants to install lighting along a drive and not disturb the landscaping by digging a ditch........Lets look at the ways to do this job.

# 1 - Dig the required ditch to depth( no way
says mr CM)
# 2 - Use irr pipe (We have killed that idea)
# 3 - line bore (Not brought up but way too
expensive.)
# 4 - How about short maybe 24 in. sections
of kindorff 2/3 coated in mastic driven
in the ground within required distance
from boxes,Secure the t 11 box with
approved method,pull wire for the
lighting and terminate the lighting.
It can be painted to match shrubs
mulch etc.Everyone is happy CM no digging
h/o`r has lighting,EC gets paid
352.10 F does that apply in this
sensrio? it would at best be a judgment
call

 

[JohnE]

Re: Underground UF Installation

The argument that I've heard against sleeving UF cable in irrigation pipe is that someone may confuse it with a water line in the furure and cut into a pipe containing live wires. Definitely a possibility, With that said I do not believe that the NEC prohibits this practice. Massachusetts adds a FPN to article 300.5(A) which states "Cables suitable for direct burial are often sleeved in various raceways for design reasons. If such cable is installed with sufficient cover for direct burial, then the characteristics of that raceway need not be evaluated. Other rules of this codethat apply to raceways generally may apply. See 300.5(H)"

300.5(H) requires the use of a bushing where cables emerge from a raceway as a direct burial wiring method.

 

[iwire]

Re: Underground UF Installation

Originally posted by jwelectric:
[QB] I have lived through a debate similar to this one before and I am sorry to inform you that it is illegal to install UF cable in any other raceway than one that is listed for the purpose.

Mike that is your opinion it is no more a fact than mine.

The only difference is my opinion uses common sense.

I can not agree with you based on the NEC, I do not care what NC says.

 

[iwire]

Re: Underground UF Installation

Originally posted by jwelectric:
Are we saying that this installation would comply? These conductors are approved for direct burial.

Mike I get nothing from that link.

 

[roger]

Re: Underground UF Installation

Bob, here is the text from Mike's link, it was a question asked on another forum.

slotted plastic tile

--------------------------------------------------------------------------------

I just read the "Underground conduits are required to be sealed or plugged." thread. Around here people frequently use slotted field tile with direct burial wire. Is this a proper practice? Any concerns? Sealing conduits makes sense though I've never seen it done. I'll be watching out for it on future jobs

Roger

 

[petersonra]

Re: Underground UF Installation

I got a question about slotted drainage tile being used for prtection of UF.

It sounds to me like a good idea and I see no reason not to do it.

You don't need to seal it because it is not a raceway in the first place.

[ November 16, 2005, 04:12 PM: Message edited by: petersonra ]

 

[iwire]

Re: Underground UF Installation

Thanks Roger, I had seen that much I thought there was a picture I was missing.

What is 'slotted field tile'?

 

[allenwayne]

Re: Underground UF Installation

Just to clarify in my post I was referring to electrical conduit not irrigation pipe.Either way it is still a judgment call.What constitutes protection from physical damage???
Also is it at all permissable to protect with irrigation pipe.
352.100says it can`t be subject to crushing(another judgement call)RNMC that is.Now if the CM is willing to install concere edging that you can have conduit in place prior to and there will be 2 in of concrete over it this thread could end with that.

 

[pierre]

Re: Underground UF Installation

"Massachusetts adds a FPN to article 300.5(A) which states "Cables suitable for direct burial are often sleeved in various raceways for design reasons. If such cable is installed with sufficient cover for direct burial, then the characteristics of that raceway need not be evaluated. Other rules of this codethat apply to raceways generally may apply."

Even though it is not stated as such in the NEC, this does make sense. I like it, someone should enter this as a proposal for 2011, and we could end this argument in a few years