Friday, February 5, 2010

Light switch installation pictures

I have some pictures of light switches installation and wiring work in progress. I thought that maybe some readers would be interested in them.

Picture 1 – Light switch picture

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Picture 2 – Close up view of the light switches

As with the installation of all electrical components, the installation of light switches need to take into consideration a number of factors.

For light switches, the following requirements must be incorporated into the design drawings and the specifications.

a) The grouping of light fittings

The grouping of lighting luminaries into single control should be done in small groups or on individual luminaries.

The grouping should be arranged in such a way that unnecessary lights can be switched off while allowing sufficient luminaries to be operating efficiently to give the required level of light over the working space where the activities is ongoing.

This is part of the overall effort to lower the operating cost and conserve energy.

Diagram 3 below shows a lighting design layout of an office room. Diagram 4 is the layout of the lighting for the reception area, while Diagram 5 shows the layout for the waiting lounge, the computer room and the interview room.

All these rooms were actually part of a very large government office building.

For readers who are not too familiar with electrical drawings, I have included a list of some of the symbols used in the diagrams at the end of this post.

If you feel uncomfortable jumping up and down between the diagrams and the symbols, you can just open this page in two windows.

Resize each of the windows so that each window will fit about half of your computer screen and then locate them side-by-side.

Then position the second window at the legend area, while you use the first window for reading.

Diagram 3 – Officer Room lighting layout

Diagram 4 – Reception Area Lighting Layout

Diagram 5 – Interview Area Lighting Layout

Diagram 5a – AHU Room Lighting Layout

In Diagram 3, you can see the designed layout of one of the officer rooms in the office.

Two types of light fittings are used there: the halogen down lights and the PLC down lights.

The PLC down lights are those with the attached letter “E”. the E actually means that the lights are connected to the “Essential” electric supply of the building. The essential electric supply is backed up by the standby electric generator. If the public utility supply fails, the standby electric generator will automatically kick in and provide supply to some of the electrical loads in the building especially those that operate Fire Protection equipment and security services.

If the PLC down lights are not connected to the essential supply, then the same symbol is used but without the letter E. Refer to the list of symbols again to gain better understanding.

As you can see in the diagram, there are four PLC down lights used and they are located at the center area of the room. While the halogen down lights are installed towards the perimeter walls.

The dotted lines connecting all four PLC lights means that all the light fittings are controlled by the same switch. The direction of the black arrow at one of the lights indicates where the switch controlling the lights is located. In this case, it is at the wall near the entrance door. Observe the switch symbols on the wall.

Yes. There are two switch symbols there. This means that there are two light switches controlling the lighting in the room.

The second switch controls all the second type of light fittings, the halogen down lights. There are eight halogen down lights and all of them are controlled by one switch.

If you have checked the description of symbols, then you know that these halogen lights are provided with dimmer. You can increase or decrease the brightness of the halogen lights in the room.

Therefore the grouping of the lighting in this office room is done with just two groups, and therefore two switches of single pole type are used.

The two pictures the I show at the beginning of this post is the actual pictures of these switches. This building is still under construction. That is why you see it is still dark outside the entrance door on the left.

You may wonder why there are so many switches in the picture. Allow me to explain a little bit here.

The two rectangular plates on the right are the light switches. If you click on the picture, you may see the picture better. The bigger-sized component at the far left, nearer to the door, is the temperature control of the air-conditioner for the room.

The rectangular plate next the aircond temperature control is the PA (public address system) volume control. For the un-initiated, a building PA system is the equipment that is used to make a public announcement to the whole building from the building Fire Control Center. His is also the system that the firemen use to make emergency announce to the building occupants in case of fire.

Back to the light switches. Some of you may wonder why there are a total of six light switches on the switch plates. So below is why.

This building is still under construction. The lighting layout diagram that I showed you is the design drawing. This is a fast track project and the design process is still in progress while the construction work is already in progress.

The designer proposed that the lighting in the room should be controlled in a minimum of two groups: the center lighting and the dimmable room perimeter lighting.

I agree that it is not a very efficient control of the room lighting.

However, this is a fast track Design-and-Build contract. In this type of construction contract, the design consultants are under the Design-and-Build contractor.

The design consultants need to make their designs as optimized and lowest cost possible. Otherwise, their client (i.e. the Design-and-Build main contractor) may not be happy and their employment in the project may not last very long.

Naturally, the lowest cost lighting control would be their first choice proposal in their design. The result is what you can see in the above design of the lighting layout.

However, as the design was also still in progress, the input from the owner of the building was still flowing in. By the time the wiring work commenced, the building owner has indicated that they wanted a more efficient use of energy for the building.

As a result, the final agreed decision was that each two down lights should be controlled by one switch.

That is why you see two yellow light switches, and four white switches. The yellow switch as a color-coding indicating that the lights controlled by the switch are supplied from the building’s “Essential Supply”. While the white switches control the lights under normal mains supply.

The halogen type of light fittings was also changed to PLC downlights so that only one type of light fittings were used for this office room.

With this change, the dimmer function of the halogen down lights was also omitted from the final design. That is why you do not see any light dimming switch in the switch pictures.

That is the first basic of light fittings grouping. There are two more diagrams above that I have not yet explained. But I think you may be able to make some sense of the grouping. I will come back to this post later and give explanations on the other two diagrams.

Now let go to the second point: the light switch labeling.

b) Lighting switch labels

Where group switching is implemented, clear identification should be provided near the switch to indicate the lighting area controlled by a particular switch.

For example, if a switch controls a number of light fittings over the main entrance of a lobby, then a label indicating “MAIN ENTRANCE” should be provided at the switch.

The above diagram on Office Room lighting does not need labels at the switches. This is only an issue of practicality. However, if you really think the labels will do you good, then by all means do put those labels at the light switches in your office and at your house.

With that said, there are many places that really need these labels but are not provided with any. They are usually public areas with large lighted spaces.

In this type of public areas, the lighting controlled at a switch center. Even though the operator of the facility is responsible to control the lighting, some places do not have this sort of operator, such as the universities and colleges.

At a large open air public food court ventilated by a ceiling fan, for example, a patron may have a real difficulty trying to find which switch controls the fan above the table he is sitting at.

Picture 6 below shows an example of such installations. Picture 7 show the close up view of the switch center.

Picture 6 – A switch center

Picture 7 – A close-up view if the switch center

Picture 8 – Food court lighting

Picture 9 – Food court high bay lighting and (high bay?) ceiling fans

The top three rows are the ceiling fan speed regulators. Below them are two rows of switches. At the bottom row are the lighting switches. The row above them is for the fan ON/OFF switches.

There are eighteen fans and 27 light switches. All the fans are for the eating table area. Most of the light switches are also for the same area.

The whole eating area is out of the line of sight from the switch center.

You can see from the close-up picture that there are a number of handwritten black labels near a few fan switches.

You can also see that a few of paper stickers have been used as labels at the light switches. Actually, the cleaners for the facility have to spend a bit of time now and then to clean the switch plates from stickers like these.

So the best course of action is to just provide the labels during the electrical installation stage. End of story.

c) Locate the switches at accessible locations and within line of sight

Switches should be provided at accessible locations that are within the line of sight from under the light fitting controlled.

Exceptions to this are usually enclosed staircases and corridors used by the general public.

For these areas, the location of the switches is selected to prevent abuse or unintentional operation by members of the public. Control of lighting for these types of spaces should be done by someone who is in authority over the area concerned.In many cases, these switches are located inside locked electrical rooms. In more advanced designs, these lights are controlled by a timer or the building control system so the lights are automatically switched on and off without human intervention.

A manual bypass switch is usually provided where automatic controls are implemented.In those parts of the world where the climates are seasonal, some form of sensors (e.g. daylight sensor) is also commonly utilized.

d) Grouping of the lights should be coordinated with day lighting

The grouping of the lights should be so arranged that they could be switched off parallel to the windows.

This will allow the row of lights nearer to the window can be switched off when the effect of daylight from outside the building is already adequate for the activities in the room.

I have some diagrams that can be used to illustrate this point clearly. I will upload these diagrams into this post soon for the benefit of those who need them.

e) Alternate switching

Further control in the levels of lighting should be arranged by the use of alternate switching. For example, in a row switching arrangement, alternate luminaries in the same row should be grouped under the same switch.

In this way, it is possible to switch off half the lights (thereby reducing half of the energy consumption) while maintaining a reasonable uniformity at the same time.This method can be taken further by arranging the grouping to give three or four lighting levels. For example, the corridor lighting at hospitals can be arranged into three alternate switching groups.

After 7 pm, one of the three groups of lights will be switched off, reducing the energy consumption by all corridor lights throughout the hospital by one third.

That is a significant amount of kWh for large hospitals.After midnight, the second group of lights will be switched off, reducing the consumption by a further one-third. That means after midnight only 33 percent of the corridor lights will be “ON”, and these lights are one of three alternately throughout all the corridors.

List of electrical symbols

The following gives a brief description of some of the symbols used in the above diagrams. I did not put it up near the diagrams because they may interfere with the flow of this article.

Besides, I may add more pictures and other materials to this page in future, which also means more symbols. So locating the symbols at one place now may be a better idea.

Lighting symbols:

Symbol 1 – 9-inch diameter PLC downlight (Essential)

(Coming soon)

This is a variation of compact fluorescent type of downlights. The rating of the lamps actually used was 2 x 26W (two tubes of 26W each). You can see the light fittings in the following picture.

Picture 10 – Recessed-mounted 9-inch diameter 2 x 26W PLC downlight

Symbol 2 – Halogen downlight complete with dimmer switch

This construction of this type of light fitting is similar to the above PLC downlight. Only the bulb (and maybe the diameter) is different. However the owner later decided during the design development stage to use only the above PLC downlights for the office room.

Symbol 3 – Emergency light

As the name implies, this light fitting is not for the normal lighting of a space or room. It will only light up when there is no electricity supply to help with the evacuation of the building occupants.

Under normal conditions, these lights do not light up. They are also not provided to any switch that can be operated by normal user. Picture xx below show a picture of this light fitting in actual installation.

Picture 11 – Emergency light

The square red-color thing you see at the top left corner of the plate is the TEST push-button. Since this light is never on except when there is no electric supply, there has to be a way to check if the light fitting is healthy and can function properly when it needs to. So this TEST pushbutton is used to check it.

Since it is not meant for general lighting, the rating of the bulb is usually quite small. The standard rating nowadays is 1 x 8W (one lamp of 8 watt rating).

Symbol 4 – Exit light

This lighted exit sign is required by all building bylaws as far as I know. The same applies to the emergency lights above.

This fitting is actually not for lighting, but as a lighted sign.

However, its design and construction is more or less similar to the emergency light. The only difference is that this exit light is always ON. The emergency light is only lighted when there is no electric supply.

The power rating of the lamp is also usually the same as the emergency light: 1 x 8 watt.

Symbol 5 – Light switch

As described at length earlier, this is the symbol of the lighting switch. Usually when this symbol is used, it is a wall-mounted switch.

The rating of the switch for normal building uses is 5A or 10A.

Some other miscellaneous pics

Well, I need to rush off now. But I will come back and finish this post soon.

See you again.

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

Copyright Light switch installation pictures


Anonymous said...

how to draw a ceiling plan thats shows lighting fixture. light swtich control and ighting circuit ?

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