I haven't run conduit in concrete before and I was wondering if anyone out there knew of any good sites to get info? Looking to run it in the slab and walls in new construction.
Any resources would be appreciated.
Thanks Guys!

Not much to it, make sure that you fasten the conduit down, or it will "float" during a pour. Also, cement workers can be brutal on anything you put in.

What kind of conduit are you running? PVC or smurf tube seem to be the norm. If using smurf, it's handy to use PVC 90's on your stub ups.

I'm sure others have some other tips to share

In my experience, cement workers are nowhere near as brutal to the UG work as landscapers Smurf can be a pain to fish due to its tendency to run in almost any direction but "straight". For short runs smurf tube is ok, but use sched 40 pvc for the long stuff and try to make gentle bends and turns in straight lengths of pipe rather than 90 and 45 things to death. In an ideal world, you could have just two 90's.. at each end of the run. You will notice a big difference at pull time. This counts double for long runs, where a fish tape tends to want to bunch up in the straight mid section of the run rather than navigate bend after bend. If you are doing a really really long run and anticipate needing some strong pulling force, you might want to use metal 90's, as these are not suceptable to "burn through" from the heat caused by the friction of pullstrings or wires. I have seen this only in extremely long pulls (~100 feet and over), but it is something to consider... Hope that helps.

I am kind of "anal" about my work, and I will share one more thing, optional for all but the kooky neatnicks like me- you can use rebar "stakes" driven into the ground and tie wire to keep your conduits straight and level where they come up out of the slab. I have also seen 1/2" emt used to do the same.. In this case I have observed that concrete workers don't care (and really why should they?) where YOUR pipes come up.. if they come up inside the wall or, 3" outside it. It's just one way to ensure that your pipes stay where the plan intends them to be. I have never had a concrete guy not respect my intentions as far as UG pipe goes when I went to the trouble of bracing it so it stands up the right way and in the place it was intended to go.

Ditto on the ridgid 90's
buy 12" ridgid stubs
for your uprights
they hold up better to the abuse
and dont break off in the cold

Run schedule 40 pvc , use rigid 90 to turn up out of the pour, (I even go as far as putting 6" rigid nipples on the 90 to make sure they end up above the pour) I tried using pvc 90 but they break when some one trips on them or hits them , stake the pipe down - it will float if not plus concrete men will trip on it kick it etc etc
use as few factory 90 in the pour as possible - just " bow " the pipe it will pull easier later on, tie the pipe down, make sure all stub ups are straight by staking the 90 with long peices of 1/2 emt the emt can be cut off /broken off later, oh yeah make sure you tie down the pipe. securing the conduit is importent -one thing I always do is to put my big yellow boots on and be right there when the concrete is poured. Have a box with fittings, glue , tie wire , tools etc etc with you , this way you will be ready if a pipe gets broken. But do not be afraid to
" keep " the concrete men in line ! I have run thousands of feet of pvc in the slab. One more very important item - MAKE SURE NO STONES/ DEBRIS GET INTO THE PIPE.

Thanks for the great info!

Lucky,

By "rigid", are you referring to RMC, or to some variation of PVC (sched 80?)? If RMC, do you just change from plastic to metal with no bonding to ground the RMC?

Robbie you should always use PVC for underground work. The acid in the soil will not eat away at it as it would the metal conduits. I also use rebar to support my ppie coming up out of the slab. And I will ALWAYS let at least 2 1/2 - 3 foot of pipe stick above the slab. This will lessen your chances of getting cement into you pipe and the other contractors will see it and not have it as a tripping hazard. When the time comes to trim your pipe just cut the pipe and the rebar flush. I also use a vacuum to suck my pull string through rather then fight pushing a fish tape around the corners.

Good luck, hope these few tips will work for you.

Bert

I always used a full 10 foot stick of rigid metal conduit where I came out of the slab. Reason one: at least five feet of metal gives a lot of strength to the sweep. Reason 2: 3-5 feet of riser is noticed, and gives me a chance to straighten the pipe easily if it needs tweaking when it comes time to finish the run.
As far as bonding the conduit, I would depend on the locknuts in the box for the bond.

Solar -
Yes I mean rigid metal conduit ( rmc )
we screw a pvc female adaptor to the rmc 90.
As far as bonding the rigid metal conduit...
the bond is created when we install locknuts at the box then we pull a grounding conductor through the conduit then bond the box with a approved green ground screw. We pull grounding conductors in every conduit. Oh by the way I use schedule 40 pvc in slabs

Be Smart and Do It Right

[This message has been edited by luckyshadow (edited 02-04-2005).]

Lucky,

Thanks for your reply.

When Im running underground conduit, I like to use pvc, and then for the stub ups, cut a 10' stick of RMC in half, and bend stub 90's on the threaded ends. then you can change over with an F/A underground, and have a full 4 feet of RMC comming out of the slab, which I like to paint orange for safety (if its not going to be exposed). There is nothing worse that a guy drive over a 90'that has a short nipple with a lift and snapping the threads off. And with the extra length, if your going into an outlet inside a wall, you have no problem hickeying it over to exactly where you need it and cutting it to length. If you have many stubs that are gonna be going into a panel, then go ahead and strap them to strut, with the back of the strut where the face of the wall will eventualy be (if the panel will be mounted strait to the wall), and support the strut by using 1/2" or 3/4" emt on each side of the rack. With the 4' or so of RMC coming out of the slab, you dont have to waist time and money with changing over to emt or cutting custume RMC nipples, you just have to sawsall all the pipes down to the correct length, and use ridgid set screw connectors. and you can just break the emt stakes off at the level of the slab, once it it cured.

When running conduit and boxes in concrete walls, I like to really support the conduit to the rebar with tie wire every 5 feet or even closer, and make sure the boxes are REALLY WELL supported, because when it comes time for the pour, that concrete is gonna be dropping onto your work from up to 10 feet above, and you dont want anything dislodged. One more thing I learned when installing boxes in concrete walls, if the boxes your installing are on the open form side, that is, the side that the form is not in place yet, so workers have room to work. Try to make sure there arent 20 iron workers climbing around on the rebar, because they may be pulling the entire mat out, while they are on it, and your measurment for the face of your box will be off. You may end up with the face of the box up to even an inch deep inside the concrete (have fun finding it with a hammer). Which brings me to this point. Make exact as-builts for all your boxes, so you know where to look if this does happen. (nobody's perfect, and you might end up needing to search for a box or two.)

Now a question for the guys that are familiare with work in slab walls. I've never had a problem with using regulare metel 4sq boxes with mud rings, and just taping them up really good with duct tape, the inspectors never had a problem with it either. But are there specialty boxes for this purpose? And do you use them, or do you just go with the regular boxes? I'm guessing 300.6 b permits it.

davey

I use either a standard 4" square with mud ring or a standard masonary box - either way Duct Tape becomes your best friend ! You can't use too much in this application. Another trick I have been using and teaching my apprentices is ... when roughing in boxes in concrete forms I have them "pack " the boxes with as much paper , plastic as will fit. this way should concrete find a way in - the box is already filled up. I do this also when installing floor boxes in slabs. ( which I forgot to mention to RobbieD - sorry ) Makes for a surprise if the person opening up the box later on doesn't know about it, you should hear some of the comments.

We use 4^2s with mud rings duct taped here on the few times we have done it inside the walls. We usually don't bother trying to run inside walls, seems like half our boxes end up unusable after the concrete workers get through with it (And yes we oversecure everything).

Make sure to put a pull string in your underground before they pull. Its alot easy to fix an issue now than later. And later you know who to blaim if your pull string doesnt work after they pour.