Electrical Code Question - Buried wire


An electrician is burying an unprotected UF-B wire on my property. In places it is approximately 4" (yes inches) below grade. I am quite certain this does not meet code. Can anyone tell me:     Minimum depth for buried wire w/no conduit     Minimum depth with electrical PVC Conduit     Minimum depth with electrical emt Conduit
Thanks!!
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certain
Generally speaking 24" is minimum for UF (18" for one and two family homes) and 18" for PVC. EMT is not permitted for direct burial however rigid galvanized is. If a 120 volt, 20 amp circuit is GFI protected it is permissible to run the wire at 12". I don't recommend the lesser depth or the use of a GFI to protect the entire run of wire as it will be more subject to nuisance trips. For more details look up table 300.5 in the National Electrical Code.
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I don't find the exception for one and two family homes in the 2005 NEC.

John, do you have a Code cite for that? I'm not disputing you, I'm curious. I didn't think it was permitted, either, but I couldn't find anything that said one way or the other. Article 358.10(B) says it's permitted "in direct contact with the earth" but doesn't mention burial; but 358.12 does not list burial as a use not permitted.
--
Regards,
Doug Miller (alphageek at milmac dot com)
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homes)
Table 300.5 Column 1, 6th row. Now that I read it again it might be for only under driveways.

curious. I

said
contact
burial as

Doug you are right. It can be construed from 358 that it is permissible to direct bury EMT. It's something that I have never done nor do I recall ever seeing EMT put directly in the ground. I'm not sure what fittings one would use. Raintight?
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Right, just "driveways and outdoor parking areas."

I imagine so, since EMT is approved for use in wet locations with suitable fittings and corrosion protection. Just the same, I don't think I'd use it.
--
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Doug Miller (alphageek at milmac dot com)
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On Tue, 19 Dec 2006 02:13:13 GMT, snipped-for-privacy@milmac.com (Doug Miller) wrote:

It is in the U/L white book category FJMX. EMT generally requires supplimemtal protection when used below grade. I know in Florida it turns to red dust in a few years.
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Doug Miller wrote:

It is permissible to bury EMT when it has corrosion protection suitable for conditions. The inspector is likely to require you to wrap the EMT in protective tape. There is PVC clad rigid conduit that is both better protection and more corrosion resistant. If you don't need the metal raceway for some good electrical reason such as noise protection for communications circuits then Rigid Nonmetallic Conduit (PVC) is the way to go.
--
Tom Horne

"This alternating current stuff is just a fad. It is much too dangerous
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Why would it be subject to nuisance trips?
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I was about to ask the same question.
I have all kinds of circuits (including exterior lighting -- my household wiring is a hodgpodge) which I protected with GFCIs for "belt & suspenders" purposes. An older ice box (1975? model occasionally popped a GFCI on defrost and a dishwasher that had a leak likewise occasionally tripped a GFCI.) Exterior lighting just hasn't tripped it either.
I have even left an extension cord plugged into a GFCI and after a rain storm the cord is still hot. (Not every time, but yes, I tested the GFCI.)
I not longer believe in nuisance trips. If a GFCI trips either the GFCI is messed up or there is something really wrong that can and should be fixed.

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wrote:

Yep, you're right, doesn't meet the National Electrical Code (NEC).
Understand, however, that your local jurisdiction may have requirements that differ from the NEC, so for the definitive answer regarding what's legal where you live, call your local electrical inspector. The local requirements can be either more stringent than the NEC (Chicago, for example) or less so (certain areas of rural Indiana, for example -- I used to live in a place where there was _no_code_at_all_. Scary.)
I always did my wiring to Code even though there was no legal requirement to do so, and if I had an electrician working for me, I'd insist he do the same.

Having said all that, though, here's what the NEC says about minimum cover for buried electrical installations (assuming that we're talking about burying it in your yard, not under a driveway, sidewalk, basketball court, etc): - direct burial: two feet - in rigid nonmetallic conduit (PVC): eighteen inches - in EMT (aka thinwall) -- don't know -- can't find that listed - in Rigid Metal Conduit (aka thickwall) or Intermediate Metal Conduit: six inches
Note also that if the circuit is 120V, *and* not more than 20A, *and* protected by a GFCI, it may be as shallow as twelve inches (six if in RMC or IMC).
But under *no* circumstances does it meet Code to direct-bury a UF cable as shallow as only four inches.
--
Regards,
Doug Miller (alphageek at milmac dot com)
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Code aside, that fails to even meet common sense requirements. If someone could snag it with rototiller, it is way too shallow.
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Doug Miller wrote:

Not quite true. When UF is used to run low voltage wiring supplied through a laboratory listed power limited supply it can be run at quite a shallow depth of bury. That's the problem with these types of questions. We have to assume so much to answer them.
--
Tom Horne

"This alternating current stuff is just a fad. It is much too dangerous
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It still fails the common sense test, a few years from now someone will want to put in a flower bed and destroy the entire install with one pass with a rototiller. Granted no harm will come to them if it is low voltage, but some folks actually like to have installed stuff stay installed.
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varies by location, wet/dry climate, building zoned use, earthquake zone. [?]
snipped-for-privacy@aol.com wrote:

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