- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
Is there a burial depth for conduit in concrete that is inside a building not in contact with the earth? Think of a slab on a2nd floor of a commercial building.
Under Concrete
- Thread starter Dennis Alwon
- Start date
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petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
IMO, it is not buried at all if it is not in contact with earth.
On the other hand, there are various rules about concrete encasement that might apply.
On the other hand, there are various rules about concrete encasement that might apply.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
Like what? That is what I am trying to figure out. I have not see anything that would pertain to say a conduit trenched in across a floor to be covered by say 2" concrete--- Maybe protection could be used? IDK
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
I think if you were a little more forthcoming in explaining what it is you want to do, it might be easier to give you an answer.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
Not a real situation but suppose I need to trench a branch circuit across a floor where there were half walls. Perhaps drilling thru the floor was not an option so how could I compliantly go from one half wall to the other?
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
As long as the wiring method allows you to put it in concrete, you are good to go as far as I can tell UNLESS it is a structural issue. Then you would need permission from the guy that designed the structure.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
So 1/2" under the concrete is fine? That is what I think but it seems wrong.
xformer
Senior Member
- Location
- Dallas, Tx
- Occupation
- Master Electrician
IMHO, the only thing I can recall is the requirement for Service Conductors and also 300.5
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
300.5 is for underground.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
I don't see any obvious issues with it. It would be legal to just run it along the floor.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
Yeah that would go over well....haha
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
why not? you could run it in the corners where no one would trip on it.
kwired
Electron manager
- Location
- NE Nebraska
Service conductors need to be encased in at least 2 inches of concrete to be considered outside the building regardless of whether concrete is a slab, slab on grade, or other encasement.
Might be. Put it this way it is fine with NEC, structural design purposes, might weaken the slab depending load characteristics designed into the slab and how and where in the slab you want to do this particularly when not a slab on grade.
- Location
- Illinois
- Occupation
- retired electrician
300.5 has a row for "under a building" and the required depth is "0". I see that as saying it can be in the floor slab with the top of the raceway level with the finished floor. Any depth greater than that is permitted, either in the slab itself or below the slab. Note that the engineers often have requirements for raceways in the slab that either prohibit them or restrict the size and location to help avoid cracks in the concrete.
The specs of most of my jobs required my conduits to be in the fill below the slab and not in the slab itself.
The specs of most of my jobs required my conduits to be in the fill below the slab and not in the slab itself.
kwired
Electron manager
- Location
- NE Nebraska
Good idea IMO for on grade slabs anyway.
OP is asking about embedding something in a deck not on grade, such slab will have more structural properties than one supported by the earth below it and may be critical structural wise what you can put into it and where.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
1/2", 1/4" 1/8", etc. doesn't matter. T300.5 does not apply.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
Thanks all, that what I suspected. I did know that many engineer design state the conduit to be below the slab but that isn't really possible on a second floor retro. Again this is just hypothetical as it came up the other day.
Last night we had our local association meeting on zoom and it seems everyone doubted me but no one could show me where it is stated or found in the NEC.
I agree with all that the table doesn't apply because section 300.5 is called underground installations
Last night we had our local association meeting on zoom and it seems everyone doubted me but no one could show me where it is stated or found in the NEC.
I agree with all that the table doesn't apply because section 300.5 is called underground installations
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
I seem to recall that section titles are not part of the code, or at least are not enforceable.
kwired
Electron manager
- Location
- NE Nebraska
So we can ignore the fact that art 422 applies to appliances, 430 to motors, 440 to air conditioning or 210 to branch circuits, 215 to feeders and 230 to services and probably many others that narrow down what it applies to and just pick and choose what we want to use?
Can I choose to use 300.5 for overhead conductor clearances?
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
You can ignore the TITLES, but not the text. The first paragraph of each code article tells you what the article applies to.
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