"Hollow" concrete floor?

[480sparky]

OK, so I looked at a job the other day. Scope of the work is simply relocating phone, data & power for cashwraps that are currently in a concrete floor of a large retail space in a mall.

As I talked to the store's facility manager, he keeps telling me there is 'space' under the floor to run new lines. Not a basement or crawl space.... just, as he put it, 'hollow spaces underneath'. I'm thinking this is simply a poured slab on grade and he's talking through his hat.

This would be on the lowest level of a mall store, and I can only imagine an ordinary poured floor. But the manager seemed positive I can fish under it. Store was built in the 60s or 70s. I can't imagine pre-stressed being used as a floor on grade. So my question is, is there some sort of concrete floor that does have hollow spaces through it?

 

[satcom]

OK, so I looked at a job the other day. Scope of the work is simply relocating phone, data & power for cashwraps that are currently in a concrete floor of a large retail space in a mall.

As I talked to the store's facility manager, he keeps telling me there is 'space' under the floor to run new lines. Not a basement or crawl space.... just, as he put it, 'hollow spaces underneath'. I'm thinking this is simply a poured slab on grade and he's talking through his hat.

This would be on the lowest level of a mall store, and I can only imagine an ordinary poured floor. But the manager seemed positive I can fish under it. Store was built in the 60s or 70s. I can't imagine pre-stressed being used as a floor on grade. So my question is, is there some sort of concrete floor that does have hollow spaces through it?

In the 60's we used floor duct in many of the malls, so making changes was easy http://img.directindustry.com/images_di/photo-g/floor-duct-51559.jpg

 

[cowboyjwc]

That was my guess is that there is Walker duct in there and he just doesn't know what to call it.

 

[Cow]

So how would you run electrical in Walker duct? Do you just fish flex in? Or MC? Or just bare THHN?

 

[OTT2]

So how would you run electrical in Walker duct? Do you just fish flex in? Or MC? Or just bare THHN?

Walker makes boxes, fittings etc designed to attach, mount, to their duct. Use single conductors THHN/THWN etc. Can be a pain if the original installation was not done correctly.

Are you sure it's not a concrete cellular floor, article 372?

 

[Smart $]

... So my question is, is there some sort of concrete floor that does have hollow spaces through it?

Yes.

Here is one example, which falls under Article 374 I believe: http://www.hhrobertson.com/constructiontypes/concrete.aspx

I couldn't find an example of the other type I'm aware of. It is essentially pre-cast with round holes running the length of it. When I was on the First Energy Northeast Regional Headquarters job they used it on grade level with a embedded wireway roughly in the center of the building running perpendicular to the holes from front to back. This type falls under Article 372.

 

[76teach]

Sq D made a multiple cell under floor duct system but I do not see it in the current catalog. Look into Wiremold for thier under floor duct systems. This may be where the product is today and is simular atleast.

length of duct were coupled and connected to a juntion box with an access cover maybe 16" round flush with the floor. It may also go to the equipment room from a J box and rise up out of the floor to the associated equipment. It may also have a conduit underfloor home run from J box for each type of duct section. The duct may have inserts at two foot intervals which have 1-1/4" thread hub for dog house or flex take off.

In 1960 there may only be two ducts installed. One power, small width and the other wider of course for communication cables, such as 25 pair tele cable.

Have fun.