Minimum Cover Table 300.5

[Sparky2791]

If you have a PVC conduit in a trench in a 3" concrete envelope running under a road. Is the minimum cover 12" or 24"?

 

[wwhitney]

The short answer is 24".

The long answer is that the table is ambiguous and doesn't tell you how to handle the case that your installation complies with multiples rows. Certainly taking the larger answer is conservative.

Also Note 4 tells you that when your installation complies with more than one column, then you have permission to use the shallower value. Which implies a presumption that absent note 4 you would need to use the deeper value. Which suggests the same would apply for an installation matching two different rows, although it is not spelled out.

Cheers, Wayne

 

[don_resqcapt19]

If you have a PVC conduit in a trench in a 3" concrete envelope running under a road. Is the minimum cover 12" or 24"?

Sometimes the authority that installs and maintains the road has requirements that exceed those of the NEC...assuming a public road.

 

[Little Bill]

I say 24" because of it being under a road, which is listed as an area. It's a given (in most case) that a trench will be involved, but given under a road is a separate listing, you would have to go by that column.

 

[tom baker]

And, more practically, most digging in the ROW expects the electrical to be 24” deep.

 

[drktmplr12]

And, more practically, most digging in the ROW expects the electrical to be 24” deep.

this is one reason POCO likes to be 36"

 

[steve66]

I would think the concrete encasement would be worth something, so the shallower depth of Row 2 should apply.

If not, then why was it necessary to add the phrase "with no vehicular traffic" to Row 4?

In other words, if they intended Row #2 to only apply where there isn't any vehicular traffic, wouldn't it also say "with no vehicular traffic"?

 

[Sparky2791]

Clear as Mud as usual

 

[Sparky2791]

The short answer is 24".

The long answer is that the table is ambiguous and doesn't tell you how to handle the case that your installation complies with multiples rows. Certainly taking the larger answer is conservative.

Also Note 4 tells you that when your installation complies with more than one column, then you have permission to use the shallower value. Which implies a presumption that absent note 4 you would need to use the deeper value. Which suggests the same would apply for an installation matching two different rows, although it is not spelled out.

Cheers, Wayne

I agree completely with your response. Another choose the safest way issue is digging overtop of an existing utility so the deeper may not be possible in that area. Ill ask for permission in that area. Typically can get the inspector to work with me.
Thanks!

 

[Sparky2791]

Sometimes the authority that installs and maintains the road has requirements that exceed those of the NEC...assuming a public road.

Private road

 

[RustyShackleford]

I believe it makes sense to piggyback on this thread ...

My situation is that it'd be PVC "in a trench below 2" thick concrete or equivalent", however, it's not below a road, it's below a private gravel driveway for a single-family dwelling. So I guess the conservative answer is 18", but as mentioned above, surely the concrete is worth something in reducing the required depth.

Also, any clue what the "or equivalent" means ? Could one lay the PVC in the 12" trench, add a layer of dirt, and then a continuous row of bricks on top ?