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Mello
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Join Date: Sep 2007
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Underground Power Line Depth

07/31/2015 9:18 AM

We're having the underground line between the transformer box and our house replaced, and our electrician used a trencher to dig and then started to put the line down... today, some Time Warner techs came to bury the cable line (they had to replace yesterday since the electrician cut through it), and they said the electrician should be burying the power line 18" down and it's too shallow.

Any of you wonderful electricians out there know the code for burying these underground lines? I want to be sure before I give him what for when he gets back to finish up today. Thanks for your input!
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lyn
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#1

Re: Underground Power Line Depth

07/31/2015 9:32 AM

Local codes control the depth of power and other lines.

Since we don't know where you are, we can't help you.

Your electrician SHOULD know the local codes...........................................maybe.
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Mello
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#2
In reply to #1

Re: Underground Power Line Depth

07/31/2015 9:35 AM

Sorry, I meant to say I'm in New York State, if that helps >.<

Considering we're on day 14 of this power line fiasco, I'm not sure how much I trust this electrician!
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Kilowatt0
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#3
In reply to #2

Re: Underground Power Line Depth

07/31/2015 9:45 AM

Your local power company, or building inspector will know.

Call them, they should be happy to answer this question in a way that meets local code.

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lyn
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#4
In reply to #2

Re: Underground Power Line Depth

07/31/2015 9:46 AM

No. local is local.

Most cities and states follow NEC/NFPA 70e.

If your electrician doesn't know this and can't prove it to you, fire him, or her.

Call your LOCAL building authorities and ask them.
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Mello
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#5
In reply to #4

Re: Underground Power Line Depth

07/31/2015 9:47 AM

Thanks very much, guys-- I will call National Grid and check with them. Appreciate the assistance!
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Tornado
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#6

Re: Underground Power Line Depth

07/31/2015 9:48 AM

NEC Article 300-5 and accompanying Table 300-5 give various depths, depending on type of wire, conduit, etc.

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Mello
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#7

Re: Underground Power Line Depth

07/31/2015 10:25 AM

National Grid said ask the town, and the town said it gets inspected after the work is complete, and it either passes or it doesn't, but the town office couldn't tell us what the depth was for code. Fun times!
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lyn
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#9
In reply to #7

Re: Underground Power Line Depth

07/31/2015 10:50 AM

Your tax dollars at work, making sure that you are frustrated and making sure that they have future employment by telling you what your electrician SHOULD HAVE DONE, after the fact.

That's why it's important to be sure your electrician is qualified and licensed to work in your area.
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Kevin LaPaire
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#12
In reply to #7

Re: Underground Power Line Depth

07/31/2015 3:53 PM

You would likely have to speak directly to the inspector. He is the one that is supposed to know the code applicable. As said in another post, government at work.

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ozzb
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#8

Re: Underground Power Line Depth

07/31/2015 10:36 AM

http://www.irrigation.org/uploadedFiles/Certification/National%20Electric%20Code.pdf

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tcmtech
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#10

Re: Underground Power Line Depth

07/31/2015 11:30 AM

12" to 24" is the standard here for anything that not a HV primary feed line.
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Original_Macgyver
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#11

Re: Underground Power Line Depth

07/31/2015 11:39 AM

When I was a contractor in California, the rule of thumb was to bury any electrical to a depth of 18" from finished grade to the top surface of the installed conduit.

If there is concrete covering it, it just has to be below the concrete, however, I always dug my trenches to a 24" depth so the inspectors would give me a hassle.

My electrical installs always passed inspection!

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Wal
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#15
In reply to #11

Re: Underground Power Line Depth

08/01/2015 6:44 AM

Not a rule of thumb, it's code.

ASNZ3000, 600mm deep or directly below a concrete apron.

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Original_Macgyver
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#17
In reply to #15

Re: Underground Power Line Depth

08/03/2015 9:58 AM

It is a "Rule of Thumb" if you know the proper code and follow it.

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SHOCKHISCAN
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#13

Re: Underground Power Line Depth

07/31/2015 7:10 PM

Local codes prevail however the minimum distance for direct burial cable to a residential home should be 2 feet.

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old salt
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#14

Re: Underground Power Line Depth

07/31/2015 11:10 PM

Almost all states follow NFPA (National Fire Protection Association) section 70, the National Electrical Code (NEC). I don't know of any that don't but it is possible. This is a standard, guidance only, but the states and communities adopt it as the legal code (law) for electrical work.

The section that has the information you are looking for is Article 300, Wiring Methods, and table 300-5, Minimum Cover Requirements, 0 to 600 volts, Nominal, Burial in inches.

1. Direct burial cables or conductors: 24 in.

2. Rigid metal conduit or Intermediate metal conduit: 6 in.

3. Rigid nonmetallic conduit approved for direct burial without concrete encasement or other approved raceways: 18 in

4. Residential branch circuits rated 120 volts or less with GFCI protection and maximum overcurrent protection of 20 amperes: 12 in

5. Circuits for control of irrigation lighting limited to not more than 30 volts and installed with type UF or in other identified cable or raceway: 6 in

In your case, if the conductors are being buried by themselves with no protection such as rigid conduit or IMC the required depth of burial is a minimum of 24 inches. Side note-- that why so many "Ditch Witches" have a maximum trenching depth of 24 inches!

If you want to verify this contact your local electrical inspector or check in a local library. Contacting the power company is not a reliable source for an answer on this. You will get an answer of what the depth they actually bury it at disguised as what they are supposed to bury it at. Very seldom do I see a site where they are buried at 24 inches unless the homeowner or a "good electrician" made the installation.

Good Luck, Old Salt

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suresh sharma
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#16

Re: Underground Power Line Depth

08/01/2015 7:01 AM

You should contact local contractor who is familiar with local rules. Better to get job done by such local contractor instead through a electrician.

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Users who posted comments:

Kevin LaPaire (1); Kilowatt0 (1); lyn (3); Mello (3); old salt (1); Original_Macgyver (2); ozzb (1); SHOCKHISCAN (1); suresh sharma (1); tcmtech (1); Tornado (1); Wal (1)

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