Tuesday, March 15, 2011

Cable duct crossing roadside drain

Today I have uploaded a few photographs of underground cable ducts crossing a roadside drain at a project site a couple of months ago.

Photo 1 – Underground electrical ducts crossing a roadside drain

A good design of external electrical works would have considered the situations where all the different services would cross each other.

Even when they do not cross each other, the space where all the services need to be installed may become smaller or narrower.

Therefore a good design engineer need to foresee these potential problems that may be too difficult or too expensive to be solved by the trade contractors, engineers and managers during the construction stage.

In some construction environments, all designs from the respective design consultants and engineers would be passed through a coordination stage. There the detailed design drawings are superimposed over each other.

The mechanical and electrical services over each other and scrutinized for potential installation problems.

The mechanical and electrical construction drawings against the latest architectural drawings to spot any potential construction problems.

Outside of buildings, all external mechanical and electrical services drawings need to superimposed onto the civil infrastructure construction drawings to spot any potential clash between each one of them.

When potential construction or installation problems are spotted, adjustment can then be made. Part of the system may need to be re-designed. Some underground services may need to be re-routed.

We call this design coordination.

If this design coordination is not done enough, then construction people may have to make some adjustment at site as best as they can.

Sometimes problems can be solved easily.

At other times, the adjustment or modification that is needed is so expensive or time consuming that everybody including the owner has to accept some improvised solution that may be questionable from the point of view of quality, aesthetic aspect, or even integrity of the work.

In a situation when a second grade improvised solution is adopted by the one in power over the construction contract, the best a work superintendent can do is just to make sure the safety aspects are not compromised and the installation is “fit for porpose”..

I am saying this from the standpoint of an electrical works inspector.

Enough theories. Now let’s look at the pictures that I have uploaded.

By attaching these photographs together with this article, I am not saying that this is a design error or it is a bad work by the any contractor or the designers.

A construction problem can be caused by reasons as simple as a design error by the design consultant or the trade subcontractor under-pricing a certain part of work.

It can however be caused by a bad judgment of someone or some party involved in the project. That the decision or judgment was wrong might have not been noticeable during the initial stage of the contract.

Photo 2 – Closer view of the class “C” G.I. pipes

This photograph shows a closer view of the electrical ducting crossing the concrete drain.
When electrical underground ducts cross under a road, it is a usual practice to use class “C” GI pipes for the stretch crossing the road.

Similarly when the ducts need to be exposed such as when crossing the concrete drain here, the exposed stretch needs to be using GI pipes.

Because of that, two different type of duct materials need to be jointed. The following photograph show an example of the joints.

Photo 3 – uPVC ducts coupled to G.I. pipes

Photo 4 – uPVC ducts to uPVC ducts coupler

Photo 4 shows the couplers used to extend the length of the uPVC ducts. I guess there’s not much difference between the two except the color.

Photo 5 – Opening made to the drain to allow for the GI ducts installation

Photo 6 – A clearer sectional view of the drain

See you again...

Note: This anchor post, Free electric installation pictures , may contain a summary of the materials you are looking for. It can be faster than clicking through each post title at the Blog Archive. I started it long ago but never actually got around to finish it.

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john parelle said...

great camera work and very useful information about duct works thanks to share.
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