Landscape Lighting direct burial Conduit

[profiler]

Is it okay to bury directly underground a group of 1" PVC pipes (36 runs in 3 layers) without concrete encasement? I'm confused with table 300.5. By the way, all cables are THHN in 230 Volts.

 

[roger]

Boy, that's a lot of conduits for landscape lighting. It sounds as though you should be using column 3 and you would not need encasement if you are under 2" or 4" of concrete, you would simply have to be at the proper depth depending on what condition you would be using.

Roger

 

[profiler]

Boy, that's a lot of conduits for landscape lighting. It sounds as though you should be using column 3 and you would not need encasement if you are under 2" or 4" of concrete, you would simply have to be at the proper depth depending on what condition you would be using.

Roger

Yeah it's a lot. It's just directly below the sidewalk which is made of paver blocks. What would be the cons if in case it would not be encased with concrete?

Thanks roger!

Apologies for the duplicate post by the way.

 

[roger]

Yeah it's a lot. It's just directly below the sidewalk which is made of paver blocks. What would be the cons if in case it would not be encased with concrete?

None really, if PVC is buried at proper depth and there is no digging planned in the area after installation, it will out last most other underground raceways.

The one big advantage concrete encasement will offer is protection from future excavation equipment, and depending on the size of the equipment it might not even help then.

Thanks roger!

Apologies for the duplicate post by the way.

You're welcome and no apology needed.

Welcome to the forums.

Roger

 

[jxofaltrds]

Yeah it's a lot. It's just directly below the sidewalk which is made of paver blocks. What would be the cons if in case it would not be encased with concrete?

Thanks roger!

Apologies for the duplicate post by the way.

What do you mean "just directly below"?

 

[profiler]

What do you mean "just directly below"?

The conduits will be buried below the paver blocks on a certain depth.

 

[Dennis Alwon]

I don't think pavers would qualify as covered in concrete. IMO if there are pavers then you need to be down 18" with pvc

 

[kwired]

Is it okay to bury directly underground a group of 1" PVC pipes (36 runs in 3 layers) without concrete encasement? I'm confused with table 300.5. By the way, all cables are THHN in 230 Volts.

Lets examine 300.5 since you are confused.

In general column 3 applies unless conditions in one of the other columns is met. Column 4 is the only other one that may apply, you did not mention if this is residential, but you did mention 230 volts, so that would disqualify column 4 anyway.

Looking at the rows in the table, you are not under a building so zero cover is out, you are not under a 4 inch thick slab so the 4" cover is out, pavers likely will not cut is as 2 inches of concrete cover, but this is possibly debatable, but I think most inspectors will want to see that 2 inches poured in place so you have one solid piece of concrete for a shield, that leaves us with 18" of cover for everything else except roads/highways, etc.

You mentioned your conductors are THHN, which is not rated for wet locations - which underground is a wet location. But chances are your conductors are also rated THWN which is rated for wet locations - just a technicality that can be overlooked yet dual ratings do save you in the end.

 

[profiler]

I don't think pavers would qualify as covered in concrete. IMO if there are pavers then you need to be down 18" with pvc

Thanks Dennis.

 

[profiler]

Lets examine 300.5 since you are confused.

In general column 3 applies unless conditions in one of the other columns is met. Column 4 is the only other one that may apply, you did not mention if this is residential, but you did mention 230 volts, so that would disqualify column 4 anyway.

Looking at the rows in the table, you are not under a building so zero cover is out, you are not under a 4 inch thick slab so the 4" cover is out, pavers likely will not cut is as 2 inches of concrete cover, but this is possibly debatable, but I think most inspectors will want to see that 2 inches poured in place so you have one solid piece of concrete for a shield, that leaves us with 18" of cover for everything else except roads/highways, etc.

You mentioned your conductors are THHN, which is not rated for wet locations - which underground is a wet location. But chances are your conductors are also rated THWN which is rated for wet locations - just a technicality that can be overlooked yet dual ratings do save you in the end.

Thanks for the clear explanation kwired. This is not residential. THHN is not suitable for this kind of situation but the THHN is indicated in plan. I think I should follow the 18" of cover.

 

[profiler]

Lets examine 300.5 since you are confused.

In general column 3 applies unless conditions in one of the other columns is met. Column 4 is the only other one that may apply, you did not mention if this is residential, but you did mention 230 volts, so that would disqualify column 4 anyway.

Looking at the rows in the table, you are not under a building so zero cover is out, you are not under a 4 inch thick slab so the 4" cover is out, pavers likely will not cut is as 2 inches of concrete cover, but this is possibly debatable, but I think most inspectors will want to see that 2 inches poured in place so you have one solid piece of concrete for a shield, that leaves us with 18" of cover for everything else except roads/highways, etc.

You mentioned your conductors are THHN, which is not rated for wet locations - which underground is a wet location. But chances are your conductors are also rated THWN which is rated for wet locations - just a technicality that can be overlooked yet dual ratings do save you in the end.

Thanks for the clear explanation kwired.

This is not residential. THHN is not suitable for this kind of situation but THHN is indicated in plan. I think I should follow the 18" of cover.

 

[profiler]

Lets examine 300.5 since you are confused.

In general column 3 applies unless conditions in one of the other columns is met. Column 4 is the only other one that may apply, you did not mention if this is residential, but you did mention 230 volts, so that would disqualify column 4 anyway.

Looking at the rows in the table, you are not under a building so zero cover is out, you are not under a 4 inch thick slab so the 4" cover is out, pavers likely will not cut is as 2 inches of concrete cover, but this is possibly debatable, but I think most inspectors will want to see that 2 inches poured in place so you have one solid piece of concrete for a shield, that leaves us with 18" of cover for everything else except roads/highways, etc.

You mentioned your conductors are THHN, which is not rated for wet locations - which underground is a wet location. But chances are your conductors are also rated THWN which is rated for wet locations - just a technicality that can be overlooked yet dual ratings do save you in the end.

Thanks for the clear explanation kwired.

This is not residential. THHN is not suitable for this kind of situation but THHN is indicated in plan. I think I should follow the 18" of cover.

 

[kwired]

Thanks for the clear explanation kwired. This is not residential. THHN is not suitable for this kind of situation but the THHN is indicated in plan. I think I should follow the 18" of cover.

You're welcome

Thanks for the clear explanation kwired.

This is not residential. THHN is not suitable for this kind of situation but THHN is indicated in plan. I think I should follow the 18" of cover.

You're welcome

Thanks for the clear explanation kwired.

This is not residential. THHN is not suitable for this kind of situation but THHN is indicated in plan. I think I should follow the 18" of cover.

You're welcome:huh: