I have a project where the floor is a concrete slab however it is floating, supported by building columns, because of heaving the structural engineer has designed a 18? void space between the bottom of slab and the top of grade (soil) where conduits are routed under the slab how would you support them?
Conduit supports under bldg??
- Thread starter Mike01
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masterinbama
Senior Member
- Location
- Huntsville Alabama
you are not in my area are you? The army recently sold some old BOQ'S that look like regular duplexes but are 12" slabs on grade. Local house mover bought them all and are setting them up in a subdivision.I found it hard to believe that they could move them slab and all but they did. They set them up on piles got the plumbing done then pumped grout underneath them similar to slab jacking. They ended up being very solid houses. Of course they were built to Corps of Engineer specs to begin with.As for your case an 18" crawl space would be hard to work in I would go overhead unless you absolutely have to then I would use strut and wedge anchors
This doesn't help you, sorry for that, but thought I would share.
When I was a pup I was part of a crew that installed LOTS of feeders in PVC running across a 200,000+ SF building. Barely buried them and didn't tie them down as the slab was gonna cover them up eventually. Slabs didn't get poured for weeks and we pulled in the cable. Talking lots of everything from #2 to parallel 500's.
Building wasn't enclosed yet and it rained. And rained. And rained. And flooded.
Several conduits floated up on top of the dirt (mud) with wacky bends in them. What a disaster it was.
When I was a pup I was part of a crew that installed LOTS of feeders in PVC running across a 200,000+ SF building. Barely buried them and didn't tie them down as the slab was gonna cover them up eventually. Slabs didn't get poured for weeks and we pulled in the cable. Talking lots of everything from #2 to parallel 500's.
Building wasn't enclosed yet and it rained. And rained. And rained. And flooded.
Several conduits floated up on top of the dirt (mud) with wacky bends in them. What a disaster it was.
ultramegabob
Senior Member
- Location
- Indiana
what are these conduits for? why cant you just run your circuits through the attic?
I dont know if this would pass an inspection, but its an idea. Maybe you could use some of these caddy products by fastening them to sections of pipe and assemble them as you push them under the building, you may have to bolt these to a larger base made of some kind of material that wont break down sitting on top of the ground.
http://www.erico.com/productPrint.asp?productid=1768
I dont know if this would pass an inspection, but its an idea. Maybe you could use some of these caddy products by fastening them to sections of pipe and assemble them as you push them under the building, you may have to bolt these to a larger base made of some kind of material that wont break down sitting on top of the ground.
http://www.erico.com/productPrint.asp?productid=1768
commerical installation
commerical installation
this is for a commerical facility, mostly the underground site lighting conduits 1-1/4" conduits, and conduit 1" for some floor boxes we have been informed that conduit in the slab is prohibited so if we route condiut in the void space under the slab can it just be laid in prior to the concrete being poured? or do we need to secure it to something? however the slab will not be poured yet is there a way to support conduit from the slab provisions prior to the pour of the concrete? I feel if we place it on the grade under the slab and the ground heaves that cannot be good but how can we suspended it from concrete that does not exist when the conduits are being installed?
commerical installation
this is for a commerical facility, mostly the underground site lighting conduits 1-1/4" conduits, and conduit 1" for some floor boxes we have been informed that conduit in the slab is prohibited so if we route condiut in the void space under the slab can it just be laid in prior to the concrete being poured? or do we need to secure it to something? however the slab will not be poured yet is there a way to support conduit from the slab provisions prior to the pour of the concrete? I feel if we place it on the grade under the slab and the ground heaves that cannot be good but how can we suspended it from concrete that does not exist when the conduits are being installed?
masterinbama
Senior Member
- Location
- Huntsville Alabama
Sorry I misunderstood you. I thought you meant an elevated slab not a slab on grade. For conduits up to 1" I put them down at the bottom of the gravel bed and stake them down with short pieces of re-bar and tie wire. All other sizes I bury deep enough so the sweep of my stub ups doesn't show above the finished floor.
ultramegabob
Senior Member
- Location
- Indiana
okay, if I understand, you can install the conduit before the building is there? if so, then either trench the conduit underground, or take some unistrut and dig some post holes and set the unistrut in concrete and make a conduit rack to mount your conduits to...
ultramegabob
Senior Member
- Location
- Indiana
Im not sure what your doing, is there an open space or is this just a concrete slab sitting on the ground???
- Location
- Massachusetts
Mike01 said:
I would support them from the deck, it sounds like you or you apprentice is going to have some tight working space for a while.
Depending on the conduit size I would either shoot the slab with a ramset or drill it and use steel anchors.
Not knowing what size or how many conduits you have I might even make uni strut trapezes and run the conduit on those.
me
me
I would hate to burst your bubble but I am working on the design side of things, working with an engineer on the project I do have some field installed experience that is why I am posing the question before I indicate something I want to make sure it is a resonable installatin, I find most people applying a CYA note just saying how to it but do not know how it will be installed, or if it can be installed in that fashion I am just trying to find the simplest approach to this without overcomplacting the probelm, as I said I do have some field experience (installation) and understand it's not always as easy as it seems the last time I checked murphy's law has not been repeled. Thanks for all your advice.:grin:
me
I would hate to burst your bubble but I am working on the design side of things, working with an engineer on the project I do have some field installed experience that is why I am posing the question before I indicate something I want to make sure it is a resonable installatin, I find most people applying a CYA note just saying how to it but do not know how it will be installed, or if it can be installed in that fashion I am just trying to find the simplest approach to this without overcomplacting the probelm, as I said I do have some field experience (installation) and understand it's not always as easy as it seems the last time I checked murphy's law has not been repeled. Thanks for all your advice.:grin:
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Mike, this can't be the first time this has been done. See if you can find previous elevated-slab construction jobs, and what they ended up doing.
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