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.

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Electrical panel under water pipes

The following three pictures shows example of an electrical panel installed under a water pipe.

Picture 1 – Hose reel pump starter panel



================= RELATED ARTICLES: Underfloor trunking below structural rebars | MATV trunking riser |  Cable ladder pictures | Electrical conduits and trunking pictures   | Electrical busduct installation pictures | Electric conduit installation pictures  | Electric trunking installation pictures  | Electric Panel Installation Pictures  | FR electric cable installation pictures  | Multi storey building electric closets  | Underfloor trunking pictures  | Site-fabricated electrical trunking  | Electrical Services Color Codes  | Light switch installation pictures | Electrical installation pictures

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This picture shows the hose reel pump starter panel, which is an electrical panel inside a Fire Pump Room of a multi-storey building under construction.

This building construction is almost completed and the electrical and mechanical services are undergoing testing and commissioning process.

The hose reel pump starter panel was not in my scope of responsibility. It is a part of the mechanical installation works and therefore it was under the supervision of the resident mechanical engineer.

Usually electrical panels are not installed under water pipes and this practices should never be allowed.

However, sometimes compromises had to be accepted under certain installation conditions.

This case here is inside a fire pump room at the roof an annex building. Outside the pump room was already outdoor and exposed.

As it turned out, there was a weakness in the design of the pump room layout that resulted in a very congested mechanical room.

The pump starter panel in had to be located as shown in the picture.

However, the contractor underestimated the risk of installing an electrical panel under a water piping.

Even when compromises are made, they should be made sparingly and with maximum caution.

Here two water pipes are above the pump panel as shown in Picture 2 below.

Picture 2 – Water pipes above hose reel starter pump panel



The bigger pipe present very little risk of water problem to the panel. There was no mechanical joint or connection near or around the panel that might lead to leaked water traveling to drop onto the electrical panel.

There were welded joints not far from the panel, but I did not think those kind of welded joints present too much risk. When these welded joints really fail, it would not matter much the exact location of the electrical panel because the water would get to it.

However, the smaller pipe presents a real problem. It was also directly above the starter panel and there were two mechanical joints about three meters away from the panel.

As it turned out, when I inspected the panel one of the mechanical connections was already giving away occasional drips of water. See Picture 3 below.

Picture 3 – Mechanical connections, one already started leaking



Luckily, the leaked one was on the opposite side of the hose reel starter panel. So the there was no damage to the panel yet.

However, who can guarantee the other mechanical joint would not leak?

Nobody.

Therefore, the starter panel location should be adjusted.

Instruction has actually been given and I will check again on the adjusted position of the hose reel pump starter panel.

Visit this post, Electrical installation pictures, to see more pictures of electrical installations.

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Pictures of electrical wiring

I have uploaded many pictures of electrical wiring to this blog. Now it has started to become difficult to find the pictures related to specific titles such as the wiring, etc. It will become worse as I send more post and pictures.

Picture 1 – Electrical DB wiring



Because of that, I will periodically send a post that will become an “anchor” for a specific title.

This title on wiring is one such example. Instead of being a normal post, it will generally function as the index page for posts and pictures of electrical wiring that I have sent to this blog.

So when you are looking for pictures of electrical wiring works, you can either look at the post list (i.e. BLOG ARCHIVE) at the right column of this blog page, or you can come to this post directly and scroll down to see if there is anything that interest you.

Of course, there is another way, which is by clicking the relevant “label” titles at the bottom of each page.

However, using the “label” will open all posts that have been tagged with that label in a single page. Readers with slow connections may not like the waiting when the pages are heavily loaded with graphics such is this blog.

Moreover, if multiple “labels” are opened simultaneously, readers with small RAMs may cause their computers to crawl, or even hang.

The best way is to come to an anchor post like this, which provides a short summary to posts related to a specific broad title. The graphic loading is also much less heavy because only one or two pics are added for each related post.

I have already send anchor post for other titles:

Temporary electrical installation pictures
Temporary electrical earthing pictures
Temporary lighting installation pictures
Electrical installation pictures


I will add more if there are more that three or four posts related to a specific title.

Now let’s get back to the DB wiring pictures.

Picture 1 show a house electrical DB with the cover removed.

Taken from this slightly lower angle, you can see the LIVE busbar of the DB.

Picture 2 below shows the wiring from the higher position. Here the outgoing wiring of the MCB’s (miniature circuit breakers) can be seen more clearly.

Picture 2 – Distribution Board Picture



I will not talk in detail about this wiring here. You can read a more detail description of the wiring at another post, 1-Phase ELCB Connection Pictures.

There are more pictures of this electrical DB there also.

Diagram 3 – Lighting layout and wiring details



Prior to installation of the electrical wiring conduit and trunking, the position of all fittings including the light switches, the socket outlets and lighting points must be determined.

Diagram 3 above shows examples where the light switches should be located.

I have sent a post with some pictures on the installation of lighting switches for office buildings here, Light switch installation pictures.

If you are looking for house electrical pictures, I have a post here, Home wiring pictures.

This article is not very good. It was actually a draft that I did at the time I started this blog. Suddenly something else demanded my urgent attention. That was why I did not have now post sent to this blog for a few months.

I posted the draft article anyway. I will come back to it some time soon with the final version and some pictures that may be useful for the readers.

Picture 4 – Internal wiring of an office DB showing the installation and wiring work in progress



Picture 4 shows the internal wiring of a DB for lighting and small power.

This DB was installed at a multi-storey office building. The internal wiring that has been done as shown was actually done at the factory.

That is why you cannot see any outgoing wiring from the MCB’s at the upper part of the panel.

You can see more pictures of this DB and other switchboards at this post, Switchboard earthing pictures.

Copyright http://electricalinstallationwiringpicture.blogspot.com Pictures of electrical wiring

Switchboard earthing pictures

This post provides a few pictures of switchboard earthing. They are pictures of actual switchboards and electrical DB’s that were installed in one of the projects I was involved in.

Picture 1 – LV sub-switchboard



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Picture 2 – Three-pole 160 A Terasaki MCCB and the neutral link



Picture 1 above shows a sub-switchboard at one of the upper floor of the multi-storey building.

Picture 2 shows the main isolation switch at the switchboard. I show the enlarged version of this component because I want to show the readers the neutral link component on the right of the MCCB. The neutral link is a very important part of the safety aspects of an electrical installation. I may want to refer to component later in this post or maybe when I send an update.

In Picture 1, you can see at the bottom left corner of the sub-switchboard the earthing connection to earth the switchboard front door. Picture 3 below gives an enlarged view.

Picture 3 – Earthing conductor to earth the sub-switchboard front door




Observe that the conductor is made of braided aluminium conductor. The braided type of conductor is a very good material for earthing door switchboards because the door is a frequently moved part of the board.

If an unsuitable material is used, the frequent movement of the door will either weaken and damage the conductor, or loosen the contacts at the door and the main panel cubicle. A loosened contact would increase the contact electrical resistance and defeats the purpose of having a properly sized earth conductor in the first place.

A loosened earth conductor is usually seldom noticed during the operation of the equipment until something happens. The problem is that “something” may actually be a serious electrical shock.

It is for this reason the earthing of these grounding connections should be properly checked by visual inspection during the installation works.

Notice also the termination to the switchboard door. The braided aluminium conductor is terminated using a compression type cable termination lug. It is fixed to the door using appropriately sized earthing bolt and nut with spring washers.

Picture 4 – Lighting and small power distribution board (DB)




Picture 4 above shows a floor distribution board for the lighting final circuits and also for the small power needs at the floor level.

Both the sub-switchboard in Picture 1 and this DB were not actually installed yet at the time I took these pictures. They were still on the floor at the storage area of the construction site. That is why you see these pictures were taken at angles looking downward to the boards.

The earthing connection to the front door of the board was also using the braided aluminium similar to Picture 1, as shown in the enlarged view below.

Picture 5 – DB door earthing conductor



There also is another type of panel door earthing conductor in common practice, as you can see in Picture 6 and Picture 7 below.

Picture 6 – Another electrical DB




Picture 7 – DB door earthing using green insulated PVC cable



Here the conductor is just the normal PVC insulated wiring cable with green colored insulation. The PVC cable is not very flexible. It is therefore is installed in the inverted U-shape as in Picture 7.

Sometimes the PVC cable is formed into coils between the two mounting bolts to give similar flexibility. I do not have the picture of this method now, but I will send an update as soon as I can get one.

I personally prefer the braided aluminium conductor as in Picture 1. However, contractors would normally prefer the PVC cable type because it is simply cheaper.

Manufactures would always prefer the Picture 1 method because it make the their board looks more high-quality. However, they would have to follow contractor’s choice unless the design consultant specifically stated their requirements clearly in the contract specifications.

Main Earthing Cable

In all the above Pictures, I have only highlighted the internal branch earth connections. I wish to highlight the main earthing conductors of the switchboards.

Look at the bottom of the distribution board in Picture 6. You can see at the bottom of the DB cubicle a length of green PVC insulated wire just laid there and stops just below the three-pole MCB at the bottom right corner of the DB. You can see it better in the enlarged view (Picture 8) below.

Picture 8 – Distribution board main cables



Unlike the first two electrical panels, this distribution board has already been wall-mounted in its final position. However, it is not yet wired and the cables not terminated. The electrical contractor just wanted to get my approval of the DB mounting method before they proceed with the cable termination works.

You can see the sub-main supply cables coming down from the top trunking. The outer sheath and wire armor of the 4-core armored PVC cables have been terminated with a cable gland. That is why you can see the individual cable cores coming down along the right side of the cubicle wall.

An extra slack has been provided during the sub-main cable installation to ensure there is enough length provided in case adjustment need to be made to the final position of the DB. The actual route inside the DB also may require some extra slack to the incoming cable cores.

Back to the earthing cable. The specifications for this project requires the use of 3 mm by 75 mm copper tapes as the earthing conductors for all submain circuit.

However due to installation difficulties I have allowed the use of PVC copper cables as an alternative to earth the sub-switchboards and distribution boards on case by case basis. This DB is one of the cases.

Therefore, here the main earth conductor is the PVC cable. This cable is connected to the main earthing conductor, which is the 3 mm x 75 mm copper tape, at the multi-storey building’s riser room.

You can see in Picture 8 that the earthing cable is not terminated yet. It is a common practice to provide a main earthing busbar in side an electrical board. The earthing busbar is usually pre-installed at the factory just like the rest of the components.

I do not see the earth busbar in the picture. When I went for the inspection and took these pictures, I was only paying attention to the mounting of the board. I only realized the missing earth busbar when I started to write this article. In any case, this matter would be picked up during the inspection of the internal wiring of the distribution board.

If the main earth busbar is actually missing, the electrical contractor will need to install the busbar himself at a suitable location inside the DB. The green PVC cable will then be terminated to the busbar using compression type cable lug.

The fixing to the busbar will also be similar to the door earthing method explained above: bolt and nut with spring washer.

Usually the busbar would be pre-drilled with sufficient number of termination points plus a few spare points. This will eliminate the need for disassembly of the busbar and all existing connections when additional earthing connections are needed during the life of the switchboard.

There is one more picture that I would like you to see on the earthing of LV electrical panels. See Picture 9 below.

Picture 9 – Switchboard earthing conductor



Where is the switchboard??

They have not been installed yet at the time I took this picture. These “dropper trunkings” have been installed but they stop just a few feet above the location of the distribution board and switchboard.

Observe the two lengths 3 x 75mm copper tape coming down from the electro-galvanized steel trunking. This is the standard earthing conductor used for this project. The PVC cables used in Picture xx was a replacement to this copper tape.

Earthing of 11 kV switchboards

The switchboards and the distribution boards shown in all the above pictures are low voltage boards. They are rated 240V/415V at 50 Hz supply.

Now I will show you a few pictures of high voltage (HV) switchboards. These boards are designed for 11 kV incoming supply.

Picture 10 – 11 kV switchboard rear view



Picture 11 – Closer view of the earthing copper conductor



Why do I show the rear view of these HV panels?

Because these panels are floor mounted with rear access. The LV panels above have been designed for mall-mounted installation. Therefore, they do not have rear access.

Observe the long strip in brown color at the lower edge of the switchboard. This is the earthing copper conductor for the high voltage switchgear panels.

Note: Some readers may notice that I use the terms “board” and “panel” interchangeably. For LV small electrical panels the two terms do not really have any significant difference.

However, for large LV switchboards and high voltage switchboards, the two terms cannot be interchangeable. Look at Picture 12 below.

Picture 12 – HV panel



This is one HV panel. The other big object at the left of the panels is actually another HV panel, which is still inside its waterproofed wrapping.

A high voltage switchboard consists of one or more of these panels. In other words, the panel is a section of the switchboard.

Notice the brown strip at the bottom edge of the panel in Picture 11. This is the earthing copper conductor that you see in Picture 10.

From this picture it is obvious that the long copper strip in Picture 10 is actually jointed lengths of short individual copper strip that are part of the individual HV panels.

This short copper strip at each panel has actually been installed at the manufacturer’s factory. Short lengths of the conductors are then provided complete with pre-made jointing holes and shipped together with the rest of the panels.

The electrical contractor then only needs to re-assemble all the pieces together into a complete HV switchboard.

Picture 13 – Another view of the earthing conductor




This photograph also shows the HV cables installed in the cable trench. The one going into the end panel is the feeder cable to one of the local transformers. While the other one is the incoming supply cable from the authority HV switchroom just adjacent to this HV switchroom.

Picture 14 – Substation earthing



Picture 14 shows the substation main earthing conductors. All substation should be installed with these copper tape conductor along the walls of the substation. It is usually called the substation main earthing conductors. These conductors are terminated to a main earthing busbar.

In this case, the earth busbar has not been installed yet. However the location is as indicated by my comment on the picture.

The main conductor running horizontally on the walls will be cut at the location shown. The busbar will be installed there. The cut horizontal conductors (now it has become 2 lengths after the cutting) plus the three vertically mounted conductors already there will be terminated to the earth busbar using properly sized bolts, nut and spring washers.

Note: You can also see more pictures of electrical wiring by visiting this post, Pictures of electrical wiring.


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