PVC in concrete: min depth?

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infinity

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Just deep enough so that you don't trip over it. The is no minimum depth for a raceway in a concrete floor.
 

mpoulton

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The limitation will probably come from the concrete specs and standards, not electrical code considerations. There is likely a minimum cover requirement to prevent cracking and spalling, and if this is a structural slab there will be engineering restrictions on where within the cross-section you can embed things. Shallow is always bad and sometimes prohibited; center of slab is always best and sometimes mandatory.
 

steve66

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Same 0" minimum as long as you are using a raceway listed for direct burial without concrete encasement.
Table 300.5, and for LFMC - paragraphs 350.2, and 350.10 (3).
 

roger

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What about using liquidtight ? the GC is going to cut and his curves may not necessarily be fit for pvc curve fittings.
Hot box bender, blanket, heat gun, torch, there are many ways to make PVC bends.

Roger
 

infinity

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How do you figure it doesn't apply?
And if not, what did you base your 0" answer on?

Steve
That section is titled "300.5 Underground Installations", the Table refers to raceways buried in the earth so it has nothing to do with a raceway within a concrete slab. The thread title says "PVC in concrete: min depth" there is no minimum.
 

steve66

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Seems pretty vague to me. I'm not sure its considered not underground just because we are covering it with concrete instead of earth. It's still below ground, which could very well be what they meant by underground.

And if that table doesn't apply, then everything in concrete has a 0" minimum burial depth? That doesn't sound right.

Table 300.5 requires anything under a street to be 24" deep. But using the same logic, if table 300.5 doesn't apply, then I can just put anything I want right in the slab for the street with 0" depth? Again, doesn't sound right.
 

infinity

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Seems pretty vague to me. I'm not sure its considered not underground just because we are covering it with concrete instead of earth. It's still below ground, which could very well be what they meant by underground.

And if that table doesn't apply, then everything in concrete has a 0" minimum burial depth? That doesn't sound right.

Table 300.5 requires anything under a street to be 24" deep. But using the same logic, if table 300.5 doesn't apply, then I can just put anything I want right in the slab for the street with 0" depth? Again, doesn't sound right.
The NEC chose the word underground because it's meaning is simple, just like the definition from the dictionary. It does not pertain to a raceway in concrete inside of an office building as outlined in the OP.
adverb: underground
/ˈəndərˌɡround/
  1. beneath the surface of the ground.
    "miners working underground"
 

roger

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Steve, imbedded in concrete and underground are two different scenarios, they are not dealt with the same way

Roger
 

wwhitney

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If an AHJ told me that "underground" means "below finish grade", and so 300.5 applies to a slab on grade, I would be hard pressed to definitively rebut that.

Cheers, Wayne
 
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