Forming and pouring your own concrete pull box for underground?

[JohnWalker]

I am working on a high rise building that has a complex structural slab. We have some long electrical runs below that slab that are going to require some pull boxes. Are you allowed to form and pour your own concrete pull box provided that it meets the NEC sizing requirements for a pull box? Or would it need to be a UL listed precast box?

 

[infinity]

Would these fall under 314.30 for Handhole Enclosures?

 

[GoldDigger]

Would any of that affect the structural strength of the slab? It might depend on exactly where you put them.

 

[Cow]

We've had concrete subs form housekeeping pads with recessed troughs under MCC's without any issues. I'd see this as being pretty similar.

 

[GoldDigger]

We've had concrete subs form housekeeping pads with recessed troughs under MCC's without any issues. I'd see this as being pretty similar.

Having the trough in the housekeeping pad, not the slab may be different from a handhole coming up through the slab. Worth asking the engineer anyway.

 

[mgookin]

The structural engineer should do the design while meeting the requirements of the electrical engineer, assuming code allows a non-listed box.

 

[JohnWalker]

The structural engineer should do the design while meeting the requirements of the electrical engineer, assuming code allows a non-listed box.

This is exactly what we are proposing. The structural engineer does not just want to make holes in the slab around precast pull boxes that we have installed in grade. So, he is proposing that he design the pull box and integrate it into his structural slab design. The size of the pull box will be as dictated by the NEC at a minimum. Then we would probably purchase a precast traffic rated lid to cover the pullbox and allow future access. The only thing that we were not sure about is, does a concrete pull box or pulling gallery need to be UL listed for that purpose?

 

[mgookin]

This is exactly what we are proposing. The structural engineer does not just want to make holes in the slab around precast pull boxes that we have installed in grade. So, he is proposing that he design the pull box and integrate it into his structural slab design. The size of the pull box will be as dictated by the NEC at a minimum. Then we would probably purchase a precast traffic rated lid to cover the pullbox and allow future access. The only thing that we were not sure about is, does a concrete pull box or pulling gallery need to be UL listed for that purpose?

Thank you for the clarification.

I'm going to suggest you contact the electrical plans examiner for the jurisdiction the project is in. In writing would be best (e-mail?) so you have something for your file. That's assuming these are house-owned conductors and not POCO conductors, in which case it's the local electric utility you'd be dealing with.

 

[petersonra]

Or would it need to be a UL listed precast box?

Does UL even list concrete boxes?

 

[luckylerado]

When I have pulled submittals together for the Corps of Engineers on precast or cast in place underground concrete pull boxes / handholes, the requirement has always been to provide calculations from a structural engineer. Never has UL listing been a requirement for something like this.

 

[don_resqcapt19]

Does UL even list concrete boxes?

Yes....at least some of the Quazite brand of precast underground boxes are listed.

That being said there in no general requirement that an electrical box or enclosure of any type be listed.

 

[mgookin]

Yes....at least some of the Quazite brand of precast underground boxes are listed.

That being said there in no general requirement that an electrical box or enclosure of any type be listed.

When it gets into damp & wet locations Article 314 is full of listing requirements.

 

[don_resqcapt19]

When it gets into damp & wet locations Article 314 is full of listing requirements.

There is no general requirement or a specific requirement that a handhole enclosure be a listed product.

 

[jumper]

There is no general requirement or a specific requirement that a handhole enclosure be a listed product.

The only thing I see is "identified" in 314.30 that Rob mentioned above.

 

[mgookin]

There is no general requirement or a specific requirement that a handhole enclosure be a listed product.

314.15

Am I reading that wrong?

Edit: I was reading it wrong.
Wet = listed.
Damp= no listing req'd.

 

[jumper]

314.15

Am I reading that wrong?

That section does not include handhole enclosures. 314.30 does


314.30 Handhole Enclosures.
Handhole enclosures shall be designed and installed to withstand all loads likely to be
imposed on them. They shall be identified for use in underground systems

 

[GoldDigger]

That section does not include handhole enclosures. 314.30 does


314.30 Handhole Enclosures.
Handhole enclosures shall be designed and installed to withstand all loads likely to be
imposed on them. They shall be identified for use in underground systems

And it seems very likely that the CE is capable of so identifying them.

 

[jumper]

And it seems very likely that the CE is capable of so identifying them.

:thumbsup:

 

[mgookin]

That section does not include handhole enclosures. 314.30 does


314.30 Handhole Enclosures.
Handhole enclosures shall be designed and installed to withstand all loads likely to be
imposed on them. They shall be identified for use in underground systems

I was going on the premise we were dealing with pull boxes which are described in the scope of 314 (314.1) to include boxes used as .... pull boxes .... because OP asked about a pull box

If you say it's not a pull box and it's a handhole, then that's what it is.

 

[jumper]

I was going on the premise we were dealing with pull boxes which are described in the scope of 314 (314.1) to include boxes used as .... pull boxes .... because OP asked about a pull box

If you say it's not a pull box and it's a handhole, then that's what it is.

A handhole enclosure is really just a pull box in the ground. The sizing dimensions are the same for both.