excavating under existing building for new service to building

[mshields]

I'm looking at a 5 story building, maybe 50k square feet per floor and looking at how best to bring a new 480V service to the building (it presently only has 208V). We want to put the new switchboard on the ground level which is on grade. Because of ceiling height limits, front and rear access gear is likely going to be necessary.

A colleague has suggested excavating under the building the 5 or 6 feet necessary to bring conduits up through the slab. So, compared to the footprint of the building, what we're excavating is pretty small. Still, I wonder if I should check with the structural engineer on the job. Do you think I'm being paranoid.

Or should I take my own advice and trust the paranoia. Always trust the paranoia.

Thanks,

Mike

 

[tw1156]

Is there any opportunity to locate the switchboard outside (Nema 3R) and extend 480V via conduit into building from there to each floor with transformers there? I'm unsure of your layout and every site is different. You don't have to worry about service entrance conduits entering the building at that point if you're worried about structure.

 

[petersonra]

I'm looking at a 5 story building, maybe 50k square feet per floor and looking at how best to bring a new 480V service to the building (it presently only has 208V). We want to put the new switchboard on the ground level which is on grade. Because of ceiling height limits, front and rear access gear is likely going to be necessary.

A colleague has suggested excavating under the building the 5 or 6 feet necessary to bring conduits up through the slab. So, compared to the footprint of the building, what we're excavating is pretty small. Still, I wonder if I should check with the structural engineer on the job. Do you think I'm being paranoid.

Or should I take my own advice and trust the paranoia. Always trust the paranoia.

Thanks,

Mike

I think you should check with him to make sure there is not something there already that should not be disturbed among other reasons. I think your little voice should be listened to. It won't take a lot to call the guy and ask.

 

[mshields]

your input

your input

sound advice indeed - thanks

 

[Kg808]

Hey, I have no comment on your question, but i was curious for my own understanding. I come here to learn..

How does the ceiling height effect the need for a different type of access to the switch gear? Is that a NEC code issue or building code.. etc..?

Thanks

 

[zbang]

I think your little voice should be listened to.

Sometimes, the little voices have important things to say :happyyes:. Definitely check with an architect or civil/structural engineer if you're going to go digging there.