300.5 word game

Status
Not open for further replies.
augie47

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
Had an inspector pose an interesting point/question.
300.5 states if we have conduits underground in a parking lot we need a 24" cover ("under streets, roads...driveways and parking lots")
Next door to our parking lot we build another lot but there we add a 2nd level parking area and a set of offices on the 3rd level. On both the 2nd & 3rd levels are conduits are simply in slab.
What makes the parking area on the ground level (or 2nd level) different from the adjoining parking lot with no roof or 2nd levels.
One is a lot and one is a garage ? Does the conduit know the difference :)
Do the conduits under the slab on the 3 story structure need to be 24" deep also ??
:D
 
The definition of rules should stipulate they cannot be a matter of common sense or logical. After all, if matters could be determined by common sense or logic, there's be no need for rules.
 
augie47 said:
Had an inspector pose an interesting point/question.
300.5 states if we have conduits underground in a parking lot we need a 24" cover ("under streets, roads...driveways and parking lots")
Next door to our parking lot we build another lot but there we add a 2nd level parking area and a set of offices on the 3rd level. On both the 2nd & 3rd levels are conduits are simply in slab.
What makes the parking area on the ground level (or 2nd level) different from the adjoining parking lot with no roof or 2nd levels.
One is a lot and one is a garage ? Does the conduit know the difference :)
Do the conduits under the slab on the 3 story structure need to be 24" deep also ??
:D
Click to expand...

I would say conduit underground has a hard surface below it an if the ground above it is soft the weight of a vehicle would put all it pressure on it.
Where as conduit in a slab of a parking deck the conduit flexes with the concrete and wouldn't receive as much pressure.

But what do I know.

JAP>
 
At what height in the suspended slab is conduit typically installed, relative to center line? Maybe the answer is that conduit is stronger in axial compression/tension (the typical forces in a suspended slab) than in transverse compression (the direct weight of an overlying vehicle transmitted down through the earth).

Cheers, Wayne
 
I beleive ACI 318 covers that where the the conduit diameter can't be more than 1/3 the slab depth, conduits must be spaced apart a minimum of 3 conduit widths to center, 3/4 inch in the concrete when not exposed to weather and 1.5 when exposed to weather, and cannot impair the concrete strength.
 
augie47 said:
Had an inspector pose an interesting point/question.
300.5 states if we have conduits underground in a parking lot we need a 24" cover ("under streets, roads...driveways and parking lots")
Next door to our parking lot we build another lot but there we add a 2nd level parking area and a set of offices on the 3rd level. On both the 2nd & 3rd levels are conduits are simply in slab.
What makes the parking area on the ground level (or 2nd level) different from the adjoining parking lot with no roof or 2nd levels.
One is a lot and one is a garage ? Does the conduit know the difference :)
Do the conduits under the slab on the 3 story structure need to be 24" deep also ??
:D
Click to expand...

I've always assumed the difference is that nobody (or at least anyone in their right mind) is going to try digging or excavating on the 2nd or 3rd floor:)

Under a road or parking lot, there is always the chance that pavement will be cut and removed for whatever reason, possibly along with some amount of dirt.
 
steve66 said:
I've always assumed the difference is that nobody (or at least anyone in their right mind) is going to try digging or excavating on the 2nd or 3rd floor:)

Under a road or parking lot, there is always the chance that pavement will be cut and removed for whatever reason, possibly along with some amount of dirt.
Click to expand...

I agree
 
steve66 said:
I've always assumed the difference is that nobody (or at least anyone in their right mind) is going to try digging or excavating on the 2nd or 3rd floor:)

Under a road or parking lot, there is always the chance that pavement will be cut and removed for whatever reason, possibly along with some amount of dirt.
Click to expand...


I agree also, seems like the sole reason we use that table in the first place.
 
steve66 said:
I've always assumed the difference is that nobody (or at least anyone in their right mind) is going to try digging or excavating on the 2nd or 3rd floor:)

Under a road or parking lot, there is always the chance that pavement will be cut and removed for whatever reason, possibly along with some amount of dirt.
Click to expand...


That makes more sense seeing as how Primary is usually buried at least 4' deep.


JAP>
 
Status
Not open for further replies.
Top