Building Settlement-Service Conduit Damage

[scrino]

I am currently in the electrical design process of a 40 story structure in AC New Jersey and I was informed by the structural engineer that throughout the 2 year construction process the building is expected to settle approximately 4 to 5 inches.

The 25kv RGS service conduits will be installed within the slab foundation shortly. Is anyone familiar with any installation practices or products which can be used between the conduits entering the building and the manhole to account for vertical settlement?

 

[petersonra]

use the corrugated blue plastic stuff. that way it can adjust if the buildings grows 5 inches taller too.

 

[iwire]

Perhaps bring the conduits into the building inside a heavily reinforced concrete encased duct bank that is interlocked with the foundation.

If you did this for say 50' out from the building 5" of settlement would result in just a shallow pitch of .20" per foot.

Of course maybe this would slow the settlement on one side and you end up with a leaning tower.

 

[Pierre C Belarge]

WoW!!! That is good info to have before the mess occurs.

Is it possible to install the raceways, leave the trench open and temporarily cover the top of the trench for the construction process, allowing for the movement of the building?

 

[Rockyd]

Possible to install cable in cable tray and take full advantage of the 6 ft between tie down points?

In Alaska, with oil production facilities built on basically floating islands of gravel pads, it's common to have a nice drop from facility down into tray. Gives equipment and hardware "give points" so nothing gets overly stressed. Biggest I've ran is 15 KV cable, but would think that the concept should remain the same, even with HV(35KV) cable.

B-Line Cable tray might be worth a look.

Thinking your job may have cable tray wrote all over it. At least, in the service to the building.

 

[LarryFine]

use the corrugated blue plastic stuff. that way it can adjust if the buildings grows 5 inches taller too.

Now, that was funny!

 

[macmikeman]

How about forming a rectangular "window" in the footing concrete pour and gravel backfill around the service lateral. Place the conduit at the bottom of the opening thru the footer, and let the concrete and building settle around the entry conduit.

 

[LarryFine]

How about forming a rectangular "window" in the footing concrete pour and gravel backfill around the service lateral. Place the conduit at the bottom of the opening thru the footer, and let the concrete and building settle around the entry conduit.

That would result in the conduits rising by settling amount. As long as that can be accomodated, I think it's a reasonable solution.

 

[macmikeman]

I was thinking about that, and the best I could come up with would be a sleeve at the slab around the risers. If this was my project I would send an RFI to the engineer and let him figure out the solution so that any mistake is his mistake, and if there is $kaching to be made in a change order, then Kaching.