Concrete Encased Conduits

[mstrlucky74]

Curious if anyone has ever installed conduits that had to be concrete encased. How do they encase the 5kv conduits? Build a form around them? How does that work with the trapeze? J

 

[infinity]

Build a form and pour in the concrete. We usually hang the conduit with standard rod and strut then the iron worker builds the steel support around it to support the weight of the concrete.

 

[mstrlucky74]

Build a form and pour in the concrete. We usually hang the conduit with standard rod and strut then the iron worker builds the steel support around it to support the weight of the concrete.

View attachment 20089

So those painted black racks are yours supporting the conduits or for the concrete? Doesnt the concrete need supporting?

 

[gadfly56]

So those painted black racks are yours supporting the conduits or for the concrete? Doesnt the concrete need supporting?

They appear to be for the concrete. Your drawing calls for supports every 4 feet. It also shows the "box" is re-barred to the hilt, really turning it into a beam. You didn't say if the conduits were plastic or steel, but if the latter that's just additional support for the concrete.

 

[macmikeman]

When I have to encase conduit runs underground in concrete, I put saddles not only holding the pipe up off the bottom of the trench, but also ones going to the left side, some going to the right side of the trench. I'll throw. those in between the ones every 4 foot that hold the conduit off of the bottom of the trench. Then if it is a wide trench, I'll usually build a form around the conduit as well so that if it ever has to be located and dug up there is not some 24" wide concrete mess to deal with when the thing has to get jackhammered. (if ever) This technique makes sure that the concrete will evenly flow under and around and then on top of the pipe, unlike just laying conduit in the trench and then pouring concrete on top of it. It all depends on whether there is going to be an inspector, and what type of job it is-non government but going under a driveway or under a street, or City, State, or Federal job. If nobody is looking, and its just a code requirement due to a driveway or something- just lay the conduit on the bottom and pour some concrete on top. A guy with a shovel comes along and he is gonna hit that concrete and slow himself down pretty quick. Same for a backhoe. Most guys won't just keep on digging it up, they find out what the hell it is and then deal with it somehow.

 

[infinity]

So those painted black racks are yours supporting the conduits or for the concrete? Doesnt the concrete need supporting?

Yes, the black racks are connected to the building steel and are there to support the weight of the concrete, they're installed by the iron workers. The conduit was installed first using standard threaded rod then the steel framework was built around it. Next the forms were added and the concrete poured.

Your installation had a similar detail with the exception of how the steel framework is supported with a poured concrete deck above.

 

[kingpb]

Build a form and pour in the concrete. We usually hang the conduit with standard rod and strut then the iron worker builds the steel support around it to support the weight of the concrete.

View attachment 20089

I can honestly say in all the years, I have never needed to do this. Thanks for the picture.

 

[infinity]

I can honestly say in all the years, I have never needed to do this. Thanks for the picture.

Glad to share.

I've been fortunate to work on some interesting things in the past 30+ years.

 

[steve66]

Glad to share.

I've been fortunate to work on some interesting things in the past 30+ years.

I'm sure the painter was thinking the same thing

They want black and yellow stripes like a bee? :?

 

[petersonra]

One would think that a sheet metal form could have been used that could have been left in place. sheet metal is cheap. labor to remove forms is not.

 

[Julius Right]

See for instance:
https://www.eversource.com/content/docs/default-source/ema---pdfs/c1100.pdf

 

[macmikeman]

Sorry, I skimmed and thought this was about running conduit in a trench , not suspended. Never had to do that one yet.

 

[Ingenieur]

Build a form and pour in the concrete. We usually hang the conduit with standard rod and strut then the iron worker builds the steel support around it to support the weight of the concrete.

View attachment 20089

your method makes sense
in the op detail they cast a w beam thru the duct bank
this leaves the bottom unsupported
also the side connections look insufficient imo, the 2 x 2 3/4" bolts support 4'
the 4' with concrete, cnd/cond, rebar and w beam might weigh 2800 lbs or 700/bolt in shear

also the hanger saddle is welded, no flex or give like a bolted or pinned connection
the whole 4' assy section is hanging by a 2 x 2 x 6" x 1/4" weld bead
all in shear or 24" x 1/4" x 1/4" x 1/2 = 3/4 cu in od steel
1/2 on the side, 1/2 on the bottom
each tranferring 100% or 2800 lb

 

[gadfly56]

One would think that a sheet metal form could have been used that could have been left in place. sheet metal is cheap. labor to remove forms is not.

If by "sheet metal" you mean 3 gauge steel, sure. If you mean HVAC-type sheet metal, not a chance.

 

[mstrlucky74]

Build a form and pour in the concrete. We usually hang the conduit with standard rod and strut then the iron worker builds the steel support around it to support the weight of the concrete.

View attachment 20089

Infinity, revisiting an old post. It's hard to see but are your racks the ones on top of the iron workers rack?

 

[infinity]

Infinity, revisiting an old post. It's hard to see but are your racks the ones on top of the iron workers rack?

Yes, you can see the 1/2" threaded rod in the upper left next to the word voltage.