Burial depth

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kscelectrician

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My question is about burial depth when it says " X inches to finished grade" when is that? when the electrical contractor leaves or end of project we have a liquid hydrogen test facility class 1 div 1 the end of the project called for 12 inches of white rock but it only got 3 so all the conduit is shallow i say it should be to code when you leave. thanks
 
Re: Burial depth

The finished grade is after the project is finished. That is why it is staked that way.If changes are made after the project is started and it causes an electrician to come back and redo something, he should be paid for a change order.

[ April 02, 2005, 07:03 AM: Message edited by: bradleyelectric ]
 
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The part of the project that the electrical contractor is responsible for is finished. how can he be sure requriments wont change after he is gone? he was basicly the first on the site to put in his conduit the project had a year and half after he was gone a lot of things can happen
 
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...i say it should be to code when you leave.
Click to expand...
I would agree with you on that. I believe that it is better to be deeper than more shallow. I have not yet been taged for going deeper than necessary, within reason. JMO. :p

Norb
 
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If the design documents specify a finish elevation, the electrical contractor should be permitted to base his depth on that specified finish elevation.
Don
 
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Who barries conduit that will have 4 inches of concrete poured over it ? We leave that job without proper coverage.How do we know when it will be covered ? Might also be some ran to landscape lighting and we are told they are adding a foot of fill.Have seen it happen in reverse too.Had our men run pvc from house to garage and they had 18 inches,then contractor lowers the surrounding dirt and creates a problem.
 
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I've been made to dig the trench down further, even though they were going to build up the grade. I can see where the inspector was coming from, even though I didn't like it.
 
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Where does it say we have to dig anything ? If i am adding fill of the amount required after laying the pipe then i meet the code.As long as when job is finished and before it is activated the required depth has been met then i see no way he can use nec to back himself up.We place a scrap of 2 inch pipe over the pipe vertically,that way ahj can easily measure it.
 
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Trench and put in the conduits to the finish elevations like Don posted above is about all you can do.

Jim when your placing conduits under a slab I realize that there is no burial depth required, but what are doing to keep the conduits from moving around of floating when they pour the concrete ????

We always bury the conduit so this don't happen , its a lot of work but it makes sense to me .
Perhaps you can tell us what your doing , I don't really care for all the hard work and if you have a better way please share....thanks.
 
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We always put conduits at least 3' under the fill of concrete. In factories I have worked in they like to drill all of the way through the concrete when lagging something to the floor so if they ever want to remove it they can drive the Redheads on down with a punch so they won't stick up and be a trip hazard. I agree with Don that a conduit's burial depth should only need to meet the specs given and that's all the sparky should be responsible for. That being said, I still like to put it deeper just in case. A sparky here burried #2 URD across a "yard" 24" deep for pole lights in a camp ground. They decided to cut a gravel drive for some new campsites right across this URD run. Removed 12" of sod and topsoil, dumped stone and drove over it with a concrete truck to pour RV slabs. Pushed a rock into the URD. Big mess to dig up and repair. He had rented a trencher for the job and asked me how deep he should go. I told him it was a growing camp ground and I'd go as deep as the trencher would go. It was a T&M job to begin with. Just my .02.
 
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I never thought about anchors that might be put in later ........good point though.

Did you mean 3 inches or 3 feet when you posted?

Im thinking you meant 3 inches or am I wrong ?
 
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Jim as I was sitting back thinking here, if you did not bury it some you would have some funny looking bends coming out of the concrete.

Editting to ask what do you do with the EMT as far as holding down the conduits ??

[ April 02, 2005, 05:53 PM: Message edited by: drg ]
 
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NEC says that the measurement is from the top of the pavement to the top of the cable or conduit. However, some electrical inspectors have said that we have to have 24 inches of burial depth before the crushed rock and blacktop is installed.

We have had instance where we have buried a conduit 3 feet deep and then the paving sub digs up the line with a bulldozer. We even had that happen with 7,000Y12,470 volts. Made for a nice loud boom. Caused us to miss the project deadline by 2 weeks.
 
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Amptech I seen that earier today, 3ft under a slab I guess being a contractor and owning a business the thought of problems here during a pour could put a guy right out of business and don't blame you for being on the safe side .

Perhaps the requirements in 300.5 are a bit on the liberal side and nothing to be took advantage of here when doing underground burials, there are a lot of different applications in underground that I have not yet seen and going to look at it different now.

I have had my share on problems doing underground even when we believed it was done right at the time, bulldozers, backhoes......they do locate conduits real easy and change your plans around for the worse......

Jim, Im sorry but holding down conduits down with EMT beneath a slab pour just does not make sense to me .......too much risk for problems and potential to put a company right out of business.
 
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I make a U shaped piece to hold the pvc down.Is no real danger because after my work is done they put visqueen over dirt then road mesh.Never had a problem in 22 years doing this.
As to barrying in a yard we had a cheap GC that at end of construction had a backhoe dig a big hole in back yard and barry all the trash,no was not legal.They hit our pvc runs to detached garage more than once.That was one GC i was glad we dropped

[ April 03, 2005, 08:25 PM: Message edited by: jimwalker ]
 
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"Visqueen" I have heard that name before. is that a manufactures name for plastic or something special ?

What limited experience I have with big slabs they don't use any membrane just 6 x 6 mesh and re-bar ,
perhaps it varies in different location aroung the country on how things are done , what about the concrete trucks mashing your conduits ??
Again I have only seen where they pull the truck right up and pour, then a laser type of concrete machine screeds off a rough level ....I would think all this machinery and movement would just crush the conduits and make a mess of things if they were laying on the surface.
 
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Visqueen = plastic
road mesh is what i call 6x6 wire
As to trucks driving over it,that i never seen.Here they use pumper trucks.Driving over it would not only damage our lines but the plumbers too and would leave ruts to fill.But thats here so maybe its done differant up north
 
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Concrete trucks probaly weight about the same in Wisconsin as the do in Florida Jim, serious though the slabs that I was involved in with were 14,000 sq.ft and 42.000 sq.ft and I had the luck to be involved through out both projects start to finish,
Perhaps in Florida they have soil conditions much different that up here .
These locations were in the Mississippi river area and compacted rock was use in both these locations .
The concrete trucks only imprinted as they moved in and out during the pours.....I would imagine In Florida with sand and no frost this type of construction would not be heard of .
I could see why you use pumpers then and can put conduits in like this .
 
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