Tuesday, April 13, 2010

Multi storey building electric closets

The electric closet in the following pictures has been done for a multi storey office building.

Picture 1 – Electric closet



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I wrote an article earlier on the protection of electrical panel at a multi storey office building. You can read the article here, Electric panel installation pictures.

In that article I gave a storey of how reluctant the main contractor was to provide an electrical room or cabinet in order to restrict access to the electrical panels and protect them from damages.

Access to the panel by unqualified people may lead to abuse, improper operation of the instruments inside the panels, or accidents by touching the LIVE parts inside the panels.

These panels were three-phase panels with 415V of voltage between the phases. Accidentally touching the live parts at this voltage would lead to very serious injuries. Electrocutions and immediate deaths are common results of electric shocks at this voltage.

You can see some pictures of electrical injuries and how the victim came to get them at this post, Electric shock injury pictures.

The second most important reason for having a box-up around the panels is to protect them from damages whether accidental or otherwise.

These electrical panels have not been designed for exposed installation to the general public.

The measuring instruments and indicating lamps accessible and visible at the front door of the panels are very fragile. Then can get easily damaged by accidental impact throughout the operation of the building.

When these measuring instruments and the indicating lamps are damaged, the live parts and wiring inside them would likely be exposed sooner or later.

Then you would have a very serious risk of electric shocks from the 415 volt supply.

You can see the picture of the earlier proposed mock-up below. It was the same photograph that I uploaded in the earlier article.

Picture 2 – The earlier box-up of the panels that I rejected




Even though the main contractor finally got their acts right by constructing a closet around the electrical panels as in Picture 1, it was not an easy task for me to force them to do so.

Even after I wrote my first article, there have been a few rounds of “fights”. Some main contractors are worse than car salesmen, I dare say, even though I have a lot of respect for both types of them.

I attach the following few more pictures to show you more details of the electric closet and how they are installed around the electrical panel.

Picture 3 - The lower groove for the closet sliding door



You can see here the 3 lines of groove to the sliding that would be installed later. Three groove means that the door would be split into 3 parts.

I assumed the sliding door was chosen to reduce the space taken along the corridor area.

With the width of access required to the two electrical panels and the telephone DP box, a normal swing door would need to open outside to reduce the space taken by the closet. This would block a large area of the office main corridor even when double leaf swing doors are used.

However, a contractor always thinks in terms of dollars and cents.

So I think I can pretty much make a good guess on the real reasons why they chose this type of construction for the electrical closet.

First of all, the closet walls were not actually a building construction; it was not even a dry wall type as were the rest of the internal walls of the multi storey office building.

The closet walls you see in Picture 1 were just built-in furniture constructed cheaply at site. The left and right walls were merely 1 layer of cheap plywood materials.

If normal swing doors are used, this type of construction of the wall would not be able to support the doors as they swing open.

So the contractor used sliding doors.

The closet walls are cheap and the sliding doors can be even cheaper.

Typical.

Picture 4 – Upper groove for the sliding door



Picture 5 – Access to the wiring trunking



Not only the electrical panels need to have proper access for operation and maintenance, the trunking into and out of the panels also need to have proper access.

With this arrangement, then all needed access are catered for.

Picture 6 – Ventilation through the ceiling opening



There is one last issue pending on this design: the matter of ventilation to the air surrounding the electrical panels.

During operation, the electrical panels generate heats which must be removed continuously to prevent overheating of the parts inside.

The panels themselves have been designed without ventilation opening. These are no air movement in and out of the panels.

Wouldn’t this cause the panels to overheat?

Nope.

The panel design is a fully field-tested design. The heat generated inside the panel are transferred to the air outside the panel because the panel cubicle is made of metal (i.e. sheets of mild steel materials). So the electrical panel is naturally cooled without the need for ventilation opening.

However, the electric closet in this case is not constructed of metals. So without sufficient ventilation opening, the air inside the closet would gradually get warmer.

Then slowly the dissipation of heat through steel material of the panel cubicle would gradually decrease until it finally stops when there is no more temperature gradient between the inside and outside of the electric panel.

Then you can imagine what will ultimately happen to the temperature inside the electrical panel and the electrical parts and components.

Overheat.

I raised this issue after seeing the work of the electric closet in progress.

The manager said that the sliding door would be provided with ventilation louvers below the door lockable key allowing for a path to the flow of cool air into the closet.

Then all the ceiling panels inside the closet (Picture 6) would be taken out. The hot air would be naturally routed into the ceiling space.

I would not think that the huge ceiling space would get overheated by the heat front a few electrical panels of this type.

Neat.

Now, I think I need to conclude the issue of protection and restricting access to the electric panels by saying this:

Cheap construction, but it will work. Even though I wonder how many years the wall of the closets would last, or the sliding doors.

Chiao…

P/S: See more pictures here, Electrical installation pictures.

Copyright http://electricalinstallationwiringpicture.blogspot.com Multi storey building electric closets

2 comments:

Ron Steve said...

Its a very systematic as well as made for to take the precautions from the fire.it's better for Real estate investment in Multistory apartment.I like your blog,its nice designed.Thanks for sharing with us.

Nobanno said...

I am impressed this. I am trying to know more about this.