Your opinion (conduit burial or no)

[oldsparky52]

If a conduit is installed under the decking of a wooden walkway (top of walkway is at grass level), is the conduit considered to be "buried" and therefore having to follow 300.5, or ... is it OK to lay the conduit on the dirt below the decking? When you look at the picture, remember that we are talking about (6) 3" conduits with (3) 500kcmil and (1) 3/0 in each conduit.

 

[Dennis Alwon]

How will you support the conduit? I believe it can be on the ground but support will be needed

 

[Dennis Alwon]

How much distance is there between the grass and the deck and the bottom side?

 

[Smart $]

How will you support the conduit? I believe it can be on the ground but support will be needed

:blink: The ground doesn't count as support?

 

[Dennis Alwon]

:blink: The ground doesn't count as support?

Okay how about secure and support. You are right the ground does support but does not secure....

 

[iwire]

Okay how about secure and support. You are right the ground does support but does not secure....

It's odd, we don't even think about this on flat roofs, we lay the pipe down on wood sleepers or equivalent and nothing really secures the conduit but gravity.

 

[petersonra]

IMO it is not buried.

I don't see any major issue with laying it on the ground under the walkway. As someone else mentioned, you will need to secure it in place, but it is not as if it is likely to be going anywhere.

 

[kwired]

I have no problem using the "under a building" burial depths, I'm sure not all will agree with that though. If it would actually say "under a building or structure" it would definitely be allowed.

 

[Smart $]

Okay how about secure and support. You are right the ground does support but does not secure....

The common outdoor types (RMC, IMC, PVC) only require securing within 3 ft. of termination. In between these securements, only support is required.

Now if the runs were in EMT, then he'd need to secure at intervals not exceeding 10'.

 

[Dennis Alwon]

The common outdoor types (RMC, IMC, PVC) only require securing within 3 ft. of termination. In between these securements, only support is required.

Now if the runs were in EMT, then he'd need to secure at intervals not exceeding 10'.

That is a new one on me.... I can't imagine an inspector allowing a run of 1/2" pvc laying on a roof without securing it.

In the op's case I can't imagine enforcing it to be secured but I thought it was an issue. I bet that was not the intent. They are probably thinking about below grade.

How do you secure pvc below grade where it enters a hand hole?

 

[kwired]

How do you secure pvc below grade where it enters a hand hole?

Below grade it is secured and supported by the soil around it. On grade it is supported by the soil if it is laying on it but is not secured unless additional fittings that provide securement are used.

 

[Smart $]

...I can't imagine an inspector allowing a run of 1/2" pvc laying on a roof without securing it. ...

Well, he'd be in error on that call. :happyyes:

I'm not condoning such an installation... I'm just pointing out that it would be compliant.

 

[mgookin]

Your conduit on a roof is supposed to comply with your design wind speed. Don't y'all get nor'easters up yonder?
Essential facilities especially. Fire stations, hospitals, jails & prisons, EOC's, police stations, everything that has to be operational during and after a weather event has a greater importance factor (1.15 IIRC).

If OP lays conduit on the ground under a dock, what's to prevent it from being buoyant during a rising tide or flood event? He is for sure in a flood zone (special flood hazard area as it's called).

Title of the thread is "Your opinion". My opinion is bury it.

 

[iwire]

Your conduit on a roof is supposed to comply with your design wind speed. Don't y'all get nor'easters up yonder?

Yes, but that storm covers the conduits with snow so they become very secure ...



Kidding aside I do not see either conduits or gas lines secured to the roofs here, they sit on rollers or sleepers that just rest on the roof.

 

[kwired]

Title of the thread is "Your opinion". My opinion is bury it.

Next question - how deep? If you can use the under a building row in the table depth is zero. I suppose that still means the top of the raceway is at zero and the bottom would be below the soil level.

 

[Dennis Alwon]

Kidding aside I do not see either conduits or gas lines secured to the roofs here, they sit on rollers or sleepers that just rest on the roof.

Same here-- sometimes I see them atop cinder blocks and fastened to that. Now suppose this run of pvc was going from my house to the garage on top of a brick walkway. Ugly yes but really no securing is necessary?

 

[iwire]

Same here-- sometimes I see them atop cinder blocks and fastened to that. Now suppose this run of pvc was going from my house to the garage on top of a brick walkway. Ugly yes but really no securing is necessary?

I am kind of with you here, it seems strange and yet we ignore it on a roof. :huh:

 

[mgookin]

Next question - how deep? If you can use the under a building row in the table depth is zero. I suppose that still means the top of the raceway is at zero and the bottom would be below the soil level.

How deep would you bury it in a crawl space in a flood zone?

 

[gadfly56]

How deep would you bury it in a crawl space in a flood zone?

Deep enough to keep the conduit from forcing its way to the surface due to buoyancy. Sure as shootin' that conduit will stay tight enough to act as a pontoon before it fills enough to sink back down onto the ground if left on the surface. Unless you can show that the weight with conductor fill is already more than any possible buoyant force.

 

[iwire]

Just fill it with water from the start ...