# Question About Planning Conduit in Slab



## Mastertorturer (Jan 28, 2009)

I've never run conduit in slab and was wondering how it's lined up. If you need to place your stubs exactly in the right place how do you go about that?

In a situation where cinder blocks will form walls inside a building how do you know where they end up before the floor is poured? Any tips or experiences would help too. 

Thanks for the info in advance if you got it.


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## Chris Kennedy (Nov 19, 2007)

Mastertorturer said:


> I've never run conduit in slab and was wondering how it's lined up. If you need to place your stubs exactly in the right place how do you go about that?
> 
> In a situation where cinder blocks will form walls inside a building how do you know where they end up before the floor is poured? Any tips or experiences would help too.
> 
> Thanks for the info in advance if you got it.


Take a good look at the A plans and the S plans. Look for discrepancies. DON'T FOLLOW THE PLUMBER! Get a metal 100' tape.


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## 480sparky (Sep 20, 2007)

One trick to use, especially if the slab will be covered with carpet/tile/etc., is to sub your pipes up and then wrap them with an 8" sonotube and fill with sand. Once the slab is poured, you can move your pipes up to 4" in any direction if you missed the spot. Once you've zeroed them in, you can easily remove some of the sand and pour a little bit of concrete to finish it off.

Another trick is to get all the trades to agree with two walls, or sides of the building, you're going to measure from. If everyone measure from the same two sides, then you should all be working in sync. If some trades measure from the north side, and others from the south side, and the slab is 2" off, then half the trades will be 2" off.

But otherwise, measure everything three times.


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## Mastertorturer (Jan 28, 2009)

Ok so my next question would be at what point do you get a reference to measure off of? Like some sort of landmark on the structural/architectural plans to base your run on. 

What would be a major or common mistake when doing this kind of work? Always better to hear from people who've made the mistake for ya.


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## 480sparky (Sep 20, 2007)

Mastertorturer said:


> Ok so my next question would be at what point do you get a reference to measure off of? Like some sort of landmark on the structural/architectural plans to base your run on.
> 
> What would be a major or common mistake when doing this kind of work? Always better to hear from people who've made the mistake for ya.


Ask the GC. Sometimes, it's a survey mark, a fire plug, survey stakes, just about anything can be used as a reference. If nothing else, have the GC spot you a reference, or put up a couple string lines. That way, the onus is on him.


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## waco (Dec 10, 2007)

480sparky said:


> Ask the GC. Sometimes, it's a survey mark, a fire plug, survey stakes, just about anything can be used as a reference. If nothing else, have the GC spot you a reference, or put up a couple string lines. That way, the onus is on him.


I agree, but good luck with it. I did one where every trade used its own reference and I hated every minute knowing there was no way to determine if our layout was going to work. 

Bad GC? Bad Job Boss? I don't know, but the layout drawings I had didn't specify a common reference point.

What a nightmare that one was! I don't know how it turned out since that experience prompted me to move on.


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## drsparky (Nov 13, 2008)

Read The prints. Use a lasers to keep lines strait.


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## Bob Badger (Apr 19, 2009)

Many 'A' prints clearly indicate where the measurements are coming from, either a column line or a 'control' line.

In any case DO NOT SCALE and do not go by the 'E' print.


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## wildleg (Apr 12, 2009)

lay the walls out just like you were going to build them (even though you are in the dirt or gravel), put stakes up with stringlines if you need to, and put your pipes where they need to go. Its helpful if they have some ring block up to make permanent spray paint marks so when you come back to check prior to pour you don't have to re measure everything. Putting your stubs in the wrong place will ruin your day after the concrete is in, so its good to get em right. pvc is cheap, too, so its not a bad idea to put a couple extra pipes in sometimees if it might help you later

(mark prints or your permanent notebook with dimensions you layed out so yo don't have to figure them all out again either. also, that will help in case you made a mistake or someone moved walls later but forgot to tell you about it (chaching))


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## wildleg (Apr 12, 2009)

Bob Badger said:


> Many 'A' prints clearly indicate where the measurements are coming from, either a column line or a 'control' line.


 
a rare beast. few are ever seen in the wild.


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## Bob Badger (Apr 19, 2009)

wildleg said:


> a rare beast. few are ever seen in the wild.


Odd, I see them all the time.

You don't see A prints with hard measurements given for walls?


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## user5941 (Mar 16, 2009)

The GC will show you were his stakes are located for the slab layout.You will need stakes string and a lazer level to shoot grade. A unistrut rack will help keep your stub ups staight for your panels. I usually cut short pieces of 1/2 emt to secure individual stubs.The GC will be laying out for the pour so working with him will help you locate the outside walls then stakes and string layout enterior walls. The A prints will guide you.When the GC begins setting forums for the outside walls this is when you double check your work.Be there for the pour.


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## william1978 (Sep 21, 2008)

wildleg said:


> a rare beast. few are ever seen in the wild.


 How do you even try to put in a job without the A drawings. Most of the time the GC's will give out a cd with all the drawings on them or the changes that have taken place. We just print them off at the office if needed.


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## william1978 (Sep 21, 2008)

Bob Badger said:


> In any case DO NOT SCALE and do not go by the 'E' print.


 Amen!!


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## wildleg (Apr 12, 2009)

Bob Badger said:


> Odd, I see them all the time.
> 
> You don't see A prints with hard measurements given for walls?


we get a lot of crappy prints with a lot of wrong measurements. yeah, we get A (Architectural) prints, but we don't get a lot of "grade A" prints with the measurements you need, and accurate ones at that. just did a job where the jerkitect didn't even overlay the reflected plans with the building, what a mess. I hate doing stuff twice.


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## william1978 (Sep 21, 2008)

wildleg said:


> we get a lot of crappy prints with a lot of wrong measurements. yeah, we get A (Architectural) prints, but we don't get a lot of "grade A" prints with the measurements you need, and accurate ones at that. just did a job where the jerkitect didn't even overlay the reflected plans with the building, what a mess. I hate doing stuff twice.


 Sounds like someone needs to sending out some RFI's.


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## pjmurph2002 (Sep 18, 2009)

Sounds like someone needs to send out some RFI's.

Exactly!!

The Architect is your friend when they need ideas or budget #'s. The minute there is an issue, the majority of them will go into defense mode, and blame the trades. Discrepancies need to be revealed, in writing (RFI) immediately. This gives you an opportunity to get paid for your time discovering the error, down time while waiting for a resolution and any associated costs that may occur based upon the RFI answer. Architects seem to think they can redesign the project after acceptance of the bids, without any additional costs being incurred.


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## william1978 (Sep 21, 2008)

pjmurph2002 said:


> The Architect is your friend when they need ideas or budget #'s. The minute there is an issue, the majority of them will go into defense mode, and blame the trades. Discrepancies need to be revealed, in writing (RFI) immediately. This gives you an opportunity to get paid for your time discovering the error, down time while waiting for a resolution and any associated costs that may occur based upon the RFI answer. Architects seem to think they can redesign the project after acceptance of the bids, without any additional costs being incurred.


 Well said.:thumbsup:


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## william1978 (Sep 21, 2008)

All of these stub up were laid out off using the A drawings and gear summitals. And if you look at the bottom of the picture you will see a string pulled off of the center of the column.


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## 220/221 (Sep 25, 2007)

Get *accurate* interior wall measurements from the outside forms and use string lines to locate the walls. 

Use duct taped female adapters at finished floor height and adapt to EMT above grade. Use PVC couplings if you are going to use PVC above grade. As long as the adapters/couplings are less than 1/4" below grade you will be able to see them after the floor is finished.


For block walls, find the first cell and keep everything on 16" increments. Doing under slab conduit is where I learned that there are arrows every 16" on tape measurers.




> Many 'A' prints clearly indicate where the measurements are coming from, either a column line or a 'control' line


I've only done a handfull of jobs that required a lot of slab work but I've never seen an A print. They actually give you the measurements you need? How cool is that :thumbup:. Every time I am trying to scale off a print I am wondering "Why don't they do this in the planning/drawing stage?"


PS Make sure you are on the proper side of the string. I missed a panel wall by 6" in a restaurant. 2.5" feed and about 10 3/4" branches. It wasn't the end of the world but I caught it before the framing and the concrete was still fresh. It still ruined half of my Saturday.


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## John Valdes (May 17, 2007)

I never layed out a slab before, but I have worked on many of them. I was just a pipe bending JW back then. The Electrical superintendent and the slab foreman did the layout. Carpenters used red chalk line, plumbers green and electricians blue. All the trades were on the same page, coordinated. The first floor was the most difficult. All PVC for the first floor, then EMT for all the remaining floors. I know the drawing they used was generated at the office from the main/originals provided to them by the GC. They would take the GC's drawings and draw one just for us. So we did not have to navigate around all the other trades. All we had to do was follow the marking left for us. It was easy. 
Those sure were some fun times.

Ps......It was very rare to come across a stub outside of a wall. Very rare.


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## jdrichie (Oct 6, 2009)

have the general lay out the walls for you


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## william1978 (Sep 21, 2008)

jdrichie said:


> have the general lay out the walls for you


 Why?


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## Sparky480 (Aug 26, 2007)

william1978 said:


> All of these stub up were laid out off using the A drawings and gear summitals. And if you look at the bottom of the picture you will see a string pulled off of the center of the column.


Is that a lift in the background? If so man that had to make your stomach turn every time you walked away!


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## william1978 (Sep 21, 2008)

Sparky480 said:


> Is that a lift in the background? If so man that had to make your stomach turn every time you walked away!


Yea it is a lift, but it was my own lift running these conduits. Note that the conduits are not complete when the picture was taken.


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## Mastertorturer (Jan 28, 2009)

william1978 said:


> All of these stub up were laid out off using the A drawings and gear summitals. And if you look at the bottom of the picture you will see a string pulled off of the center of the column.


#1 What are "gear summitals"?



> For block walls, find the first cell and keep everything on 16" increments. Doing under slab conduit is where I learned that there are arrows every 16" on tape measurers.


#2 What do you mean by "cell"?
#3 Why keep things in 16" increments?



> Sounds like someone needs to send out some RFI's.


#4 What are "RFI's"



> Read The prints. Use a lasers to keep lines strait.


#5 Are you using the laser to keep your referance strings straight?

Thanks again for the info. This is all starting to form a clear picture in my mind.


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## nolabama (Oct 3, 2007)

Mastertorturer said:


> #1 What are "gear summitals"?
> 
> 
> 
> ...


RFI is a request for information - submit to GC or Engineer


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## william1978 (Sep 21, 2008)

Mastertorturer said:


> #1 What are "gear summitals"?
> 
> 
> 
> ...


 Gear summitals are just a diagram of the panels,switchboards, motor control centers etc. It shows all the measurements of where to stub up your conduits how deep and how wide they are.

RFI's was answered in another post.


No laser to keep string strait just keep it in the center of the column.


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## rdr (Oct 25, 2009)

Mastertorturer said:


> #1 What are "gear summitals"?
> 
> 
> 
> ...


A cell is a block in a course of a block wall
16" is typically the length of a cell
It's also a common measurement between studs in a studded wall. 

From his profile he's an apprentice so cut him some slack


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## william1978 (Sep 21, 2008)

rdr said:


> From his profile he's an apprentice so cut him some slack


 I don't think anyone is blasting him.


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## rdr (Oct 25, 2009)

william1978 said:


> I don't think anyone is blasting him.


Just sayin for whatever smart alecks may come next and decide to. I almost blasted him myself till I thought for a second. :thumbsup:


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## william1978 (Sep 21, 2008)

rdr said:


> Just sayin for whatever smart alecks may come next and decide to. I almost blasted him myself till I thought for a second. :thumbsup:


 Gotcha.:thumbsup:


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## Mastertorturer (Jan 28, 2009)

Yeah don't blast me!:laughing: 

The whole point of this is to be competent before I even begin the task for the first time. Hopefully scaring the crap out of Journeymen who can't firgure out how I know these things. 

The motto of Navy SEALS is "Do it right the first time; evey time." & "It pays to be a winner." I agree.


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## user5941 (Mar 16, 2009)

Mastertorturer said:


> Yeah don't blast me!:laughing:
> 
> The whole point of this is to be competent before I even begin the task for the first time. Hopefully scaring the crap out of Journeymen who can't firgure out how I know these things.
> 
> The motto of Navy SEALS is "Do it right the first time; evey time." & "It pays to be a winner." I agree.


 thats all good until the journeyman thinking you know more than you actually do gives you a task that you are not ready for and you screw the pooch.


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## dawgs (Dec 1, 2007)

Then he will research it again like he did for this job and do it right.:thumbsup:


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## Mastertorturer (Jan 28, 2009)

dawgs said:


> then he will research it again like he did for this job and do it right.:thumbsup:


"first time every time!"


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