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CRACKS DUE TO ELECTRICAL CONDUITS

 
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MANOJ MITTAL
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Joined: 18 Jun 2008
Posts: 75

PostPosted: Thu Oct 16, 2008 5:50 am    Post subject: CRACKS DUE TO ELECTRICAL CONDUITS Reply with quote

dear Rabinder,
you are right, sometime such cracks occur at the location of electrical conduits(MS/PVC).Generally conduits are laid over bottom reinforcement of slab.Such cracks can be avoided if you provide and ensure proper concrete  cover to reinforcement.Further location, dia and numbers of such conduits should not obstruct in placing of concrete. Such cracks are not very common in engineered buildings. However cracks due to conduits are quite coomon in masonry walls.
regards,

MANOJ MITTAL  


--- On Wed, 10/15/08, rabinder <forum@sefindia.org> wrote:

Quote:
From: rabinder <forum@sefindia.org>
Subject: [SEFI] Location of concealed electric conduits in RCC slabs
To: general@sefindia.org
Date: Wednesday, October 15, 2008, 2:22 AM
Dear All
we embed electric conduits for electrification in RCC slabs
in all residential and commercial structures. With passage
of time the slab shows the fine crack marks but probably if
the location of conduits is at N.Axix, the possibility of
crakes may be less(not exactly know) but practically, to
find the N.A. and lay the conduits may be difficult. Plz
guide where exactly the conduits should be layed so that the
problem is sloved.
With Regards
Rabinder Shekher



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Rabinder Shekher
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PostPosted: Thu Oct 16, 2008 3:11 pm    Post subject: CRACKS DUE TO ELECTRICAL CONDUITS Reply with quote

Dear Manoj
It could have been encouraging if the reply should be post reply. This has created another topic on the sefi posts. U r right but the conduits are layed over the bottom reinforcement and even if sufficient cover to refinforcement is there, the crakes have been seen although they are less seen in engineered construction. There is one more problem in residential buildingd. After the structure is complete and before plaster work, the GI/Wter supply lines, electric conduits and CI/PVC pipes are to be layed and the plumbers/electricians cut chase in the masonary walls which after laying are made good. This also develops surface crakes on the walls and I think the structural stability of structure may also be effected. can we develop some good alternative methods for the same.
With Regards
Rabinder Shekher
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suraj
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PostPosted: Thu Oct 16, 2008 5:47 pm    Post subject: CRACKS DUE TO ELECTRICAL CONDUITS Reply with quote

Dear All,
General practice to prevent the formation of cracks over the chased conduits in the walls is to cover the portion by the expamet or the expanded metal chequers mesh. Also, wherever the different material surfaces joint occurs, the same mesh must be used.
The question of the embed conduits in the slab should be placed in the middle of the thickness as far as possible. there is no possibility of formation of cracks due to the embedment of conduits. The concrete must be vibrated properly & the flash setting should be avoided. the cracks form due to the flash setting only or due to the shrinkage. Also sometimes, cold joints are formed due to lack of supervision which requires due care. The temperature of the concrete must be controlled while the dust penetration should be avoided by all means.


P Eng Suraj Singh
Certification # PE 28
Civil & Structural Engineering
Registering Authority
Institution of Engineers (India)




--- On Thu, 16/10/08, rabinder <forum@sefindia.org> wrote:
Quote:
From: rabinder <forum@sefindia.org>
Subject: [SEFI] Re: CRACKS DUE TO ELECTRICAL CONDUITS
To: general@sefindia.org
Date: Thursday, 16 October, 2008, 8:41 PM

Dear Manoj
It could have been encouraging if the reply should be post reply. This has created another topic on the sefi posts. U r right but the conduits are layed over the bottom reinforcement and even if sufficient cover to refinforcement is there, the crakes have been seen although they are less seen in engineered construction. There is one more problem in residential buildingd. After the structure is complete and before plaster work, the GI/Wter supply lines, electric conduits and CI/PVC pipes are to be layed and the plumbers/electricians cut chase in the masonary walls which after laying are made good. This also develops surface crakes on the walls and I think the structural stability of structure may also be effected. can we develop some good alternative methods for the same.
With Regards
Rabinder Shekher







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ibarua
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PostPosted: Fri Oct 17, 2008 2:55 am    Post subject: CRACKS DUE TO ELECTRICAL CONDUITS Reply with quote

17th Oct 2008

Conduits of larger diameters displace a good deal of concrete. The present practice is to use PVC conduits. This goes to weaken the slab, particularly where large sagging moments are present. Therefore, conduits in slabs should be of MS, not of PVC. This may prevent cracks as the displaced concrete is getting replaced by steel.

Indrajit Barua.

On Thu, 16 Oct 2008 MANOJ MITTAL wrote :
Quote:
dear Rabinder,
you are right, sometime such cracks occur at the
location of electrical conduits(MS/PVC).Generally
conduits are laid over bottom reinforcement of
slab.Such cracks can be avoided if you provide and
ensure proper concrete  cover to reinforcement.Further
location, dia and numbers of such conduits should not
obstruct in placing of concrete. Such cracks are not
very common in engineered buildings. However cracks due
to conduits are quite coomon in masonry walls.
regards,

MANOJ MITTAL  


--- On Wed, 10/15/08, rabinder <forum@sefindia.org>
wrote:


Quote:
From: rabinder <forum@sefindia.org>
Subject: [SEFI] Location of concealed electric
conduits in RCC slabs
Quote:
To: general@sefindia.org
Date: Wednesday, October 15, 2008, 2:22 AM
Dear All
we embed electric conduits for electrification in RCC
slabs
Quote:
in all residential and commercial structures. With
passage
Quote:
of time the slab shows the fine crack marks but
probably if
Quote:
the location of conduits is at N.Axix, the
possibility of
Quote:
crakes may be less(not exactly know) but practically,
to
Quote:
find the N.A. and lay the conduits may be difficult.
Plz
Quote:
guide where exactly the conduits should be layed so
that the
Quote:
problem is sloved.
With Regards
Rabinder Shekher








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MANOJ MITTAL
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Joined: 18 Jun 2008
Posts: 75

PostPosted: Fri Oct 17, 2008 5:30 am    Post subject: CRACKS DUE TO ELECTRICAL CONDUITS Reply with quote

dear Rabinder,

As I mentioned earlier cracks due at the location of water supply pipes,or electrical conduits are quite common in walls even in engineered buildings.Engineered buildings are generally framed structures and hence such cracks in masonry walls are not a major threat to buildings but these must be avoided . Followings points may be important in this regards:

1. Toilet/kitchen walls which will carry such such pipes for water supply must at least be 230/200  thk.

2.Layout of conduits and pipes must be decided judiciously. It should not be left to plumber or electrician only. As far as possible layout should be straight (horizontal or vertical as the case may be).

3. Chase should be deep enough to accomodate such pipes and cement mortar/concrete. It must be finished flushed  with rest of masonry.
Curing of this surface is very important. Provide chicken mesh over this surface before finishing the wall with plaster.

4. Filling of chase after conduits are fixed must be done by skilled masons . It should not be left to plumber or electrician .

4. Provide clamps to hold GI water supply pipes. It will be better if you provide anti corrosive coatings before concealing them.

5.Chasing in RCC structural elements such as columns and beams must be avoided at any cost. It can be done by proper attention at the design stage in location and orientation of columns in cordination with services drgs.

There is nothing new in the points mentioned above but If we follow these practices such cracks can definetely be prevented.
regards,

MANOJ MITTAL

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PostPosted: Fri Oct 17, 2008 12:21 pm    Post subject: CRACKS DUE TO ELECTRICAL CONDUITS Reply with quote

Dear Mr Manoj
Thanks for providing good tips. U r right it is the acurate planning and good supervision which can control the crakes.As suggested by Dear Mr.Indrajit, it is not possible always to use MS pipes instead of PVC pipes, although can give good results. Also due to poor planning, sometimes the RCC beams are cut by the plumbers to lay the pipes, which can be avoided with planning. The method suggested by dear Mr. Suraj may be somebit difficult as to lay the pipes in the middle of slab and to keep them in position is not so easy practically. The wrapping the pipes with mesh is also a good practice.I think the chase should be grouted with concrete not to repair with cement mortor.
With Regards
Rabinder Shekher
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Vikran6721
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PostPosted: Mon Jun 24, 2019 10:52 am    Post subject: Reply with quote

Great Discussion.....

Best Ceiling Fan in India
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hemant324
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PostPosted: Tue Jun 25, 2019 5:57 am    Post subject: Reply with quote

Wonderful topic for discussion and thanks to all the members for sharing insights and mitigating measures to be adopted.

Here we need to understand the reason for cracks - the cracks generally appear wherever material of varying density and thermal properties are getting joined.

Few Common location for these cracks are -
1) At junction of brickwork and concrete beam/column.
2) At lintel level above doors and windows.  
3) At chases in walls for conduits/pipes

To mitigate the crack issue use of chicken mesh is a very effective way. It is also a very common practice in building construction.

Now how to repair cracks occurring post the construction phase. Many a times installing chicken mesh post completion of construction may be difficult and costly. In those cases you can use Epoxy injection grout for repair or use drywall tape.
Search these topics (epoxy injection grout or drywall tape for repair of cracks) on internet and you will get more than enough options than I can write here.

Hope it helps.

With Regards
H Thakur
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