under slab conduit in dentist office

[tyha]

does the conduit in a dentist office going btween the wall and the center console for equipment need to be rigid if its under slab

 

[rcarroll]

If this is a patient care area, see 517.13.

 

[raider1]

I agree with rcarroll.

The conduits run in the slab that supply equipment in the patient care area of a dentist office must comply with 517.13.

Chris

 

[220/221]

does the conduit in a dentist office going btween the wall and the center console for equipment need to be rigid if its under slab

Yes. I couldn't believe my eyes when I first read this several years ago. Absolutely stupid in my opinion. You want a 100% failsafe ground? Conduit aint it.

 

[infinity]

The raceway does not have to be RMC it could also be either IMC or EMT.

 

[220/221]

For all practical pupose, especialy in this discussion, IMC = RMC.


EMT under slab isn't allowed in all areas (like here). I was quite surprised to learn that NEC allows it.

RMC/IMC doesn't last long underground here either, even when it's pipe wrapped.

 

[Cow]

RMC/IMC doesn't last long underground here either, even when it's pipe wrapped.

Then maybe you should be using pvc coated??

 

[trex]

How about pvc in slab as sleeve and then install a/c cable thru pvc

 

[infinity]

IMO the inside of the PVC would be a wet location which would prohibit the use of AC cable.

 

[Chris6245]

IMO the inside of the PVC would be a wet location which would prohibit the use of AC cable.

If the PVC went "under" the slab I would agree....But if the PVC is "in" the slab and the slab is inside the building, How could it be considered a wet location?

 

[johnnyelectric001]

Patient care

Patient care

If it is a patient care area you can use any metallic raceway listed for the application. MC , Rigid metallic, EMT , Imc , .
GOOD LUCK !!
Keep reading it until you understand. Eventually you will see the light.

 

[infinity]

If the PVC went "under" the slab I would agree....But if the PVC is "in" the slab and the slab is inside the building, How could it be considered a wet location?

Even a conduit within the concrete would be a wet location if that concrete was in direct contact with the earth. I agree that a conduit in a slab on a floor that is not in contact with the earth wouldn't be a wet location.

Location, Wet. Installations underground or in concrete slabs or masonry in direct contact with the earth; in locations subject to saturation with water or other liquids, such as vehicle washing areas; and in unprotected locations exposed to weather.

 

[Dennis Alwon]

Even a conduit within the concrete would be a wet location if that concrete was in direct contact with the earth. I agree that a conduit in a slab on a floor that is not in contact with the earth wouldn't be a wet location.

I agree with this and if I had my book I would give you the code article.

 

[raider1]

I agree with this and if I had my book I would give you the code article.

Here is the definition of wet location:

Location, Wet. Installations underground or in concrete slabs or masonry in direct contact with the earth; in locations subject to saturation with water or other liquids, such as vehicle washing areas; and in unprotected locations exposed to weather.

Chris

 

[dcspector]

I had one where the EC ran RMC in slab and stubbed up below chair. The EC pulled HCF MC should a bond bushing be installed on the RMC stub up below the chair? Yes the MC was pvc coated.

 

[rcarroll]

I had one where the EC ran RMC in slab and stubbed up below chair. The EC pulled HCF MC should a bond bushing be installed on the RMC stub up below the chair? Yes the MC was pvc coated.

Pretty expensive run, IMO
I say if the MC is rated for wet location & the sheathing is a ground path, which apparenly it is, no bond bushing required.

 

[Chris6245]

Here is the definition of wet location:



Chris

OK....But what is between the concrete and "earth" 90% of the time? (at least in my area of the country) Pea Gravel and Visqueen...So is the concrete in "DIRECT CONTACT" with the earth? IMO no. Around here (Ohio) I very rarely see concrete poured directly on dirt.

 

[iwire]

OK....But what is between the concrete and "earth" 90% of the time? (at least in my area of the country) Pea Gravel and Visqueen...So is the concrete in "DIRECT CONTACT" with the earth? IMO no. Around here (Ohio) I very rarely see concrete poured directly on dirt.

I agree that if there is plastic under the slab then the slab is not in direct contact with the earth ............ That said, it is not a hair I would leave to split with the inspector, I would treat it as a wet location and use suitable conductors in it.

 

[cowboyjwc]

While the plastic is installed as a "moisture barrier", I would still agree with Bob, but that's probably because I'm an inspector.:grin: