Hinged louvers for maintenance

With the following pictures of 2 ft x 2 ft recessed fluorescent corridor lighting, I meant to show how the louvers of fluorescent light fixtures are provided with hinge for ease of maintenance.

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Lighting installation design

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Picture 1: 2 ft x 2 ft fluorescent corridor lighting

All parts of an electrical installation must be designed with enough provisions for access to do repair and maintenance works.

Even for the not so complicated things like fluorescent light fixtures like the ones in the above picture.

Note that the ceiling corridor here used the plaster ceiling type. Unlike ceiling panels that are removable in 2 ft by 2 ft or 2 ft by 4 ft sizes as they are installed onto ceiling tees, the plaster ceiling type needs to be broken if the maintenance need to access to the mechanical and electrical services installed above the ceiling.

After the maintenance work is done, the opening need to be sealed back to the original condition.

It is a messy work.

So here is a classic example of the need to have electrical fixtures purposely designed for access without breaking things.

Picture 2: Closer view of aluminium louvers with hinge

The above picture shows a closer view of light fixture, with the louvers swinged down and pivoted at the hinge.

While the picture below shows a few of the same type of the fluorescent lights during normal operation.

Picture 3: Lighted fluorescent lights

The provision of louvers is not only good for lighting at plaster ceiling areas; it is just at convenient where 2 x 2 ft or 2 x 4 ft ceiling is used.

Picture 4 below shows a 2 ft x 4 ft fixture installed at a 2 ft x 2 ft ceiling area.

Picture 4: 2 x 4 ft Fluorescent Light

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Mill lighting installation

The following lays lout some requirements for a palm oil mill lighting installation.


LIGHTING FITTINGS – include office, canteen, workshop and guardhouse

High-pressure sodium vapour lamps, high-pressure mercury vapour lamps, fluorescent lamps and incandescent bulkhead fittings shall be used for the general lighting within and outside the mill building. The Contractor shall submit copies of the brochures of the type and make of fittings to be supplied together with the tender documents.

For the main mill building 250W sodium vapour lamps and mercury vapour lamps are to be used for the general lighting. The 250W high pressure sodium vapour lamps shall be installed in the critical areas like the sterilizers, over the threshers, press platform and clarification station where there is a large amount of steam. These sodium vapour fittings shall be of the totally enclosed angle type fitting suitable for installation on the columns or walls of the building similar to Phillips type SNF 003 or equivalent. Where the fittings are to be installed on the outside wall of the building, these shall be of the weatherproof type suitable for tropical conditions.

In the other areas of the mill, 250W high pressure mercury vapour lamps similar to Phillip type HNT 003 or equivalent shall be installed on the columns or walls to provide the general lighting. These fittings shall be totally enclosed angle type suitable for tropical conditions c/w ballast and capacitor.

Some of the sodium vapour & mercury vapour lights within the mill and all the lights outside the mill shall be controlled by photocells and 10A switch at the individual subboards. These lights will automatically light up when it is dark.

Fluorescent fittings (2 x 36W) shall be installed under the platforms and over certain machinery to improve the general lighting in these areas.

Along the inclined empty bunch conveyor, the general lighting is to be provided by 60W incandescent bulkhead fittings installed on angle iron supports along the catwalk. The Contractor shall include the cost of the angle iron supports in the cost of the fittings.

Lighting for the Raw water treatment plant, effluent pump house and palm oil storage tank station shall be provided by 1 x 36W fluorescent lamp.

All fluorescent lamps supplied shall have a choke, starter and a capacitor housed within the fittings.

The light fittings for the compound lights shall be 250W high pressure Sodium vapour lamps similar to Phillips type SRC 511/250 installed on steel poles of not less than 8 meters in length. The steel poles shall have a diameter of not less than 150 mm at the base and shall taper to the top where the diameter of the top section shall not be less than 100 mm. The control gear of the light fitting shall be housed within a weatherproof compartment at the base of the pole. This compartment shall not be less than 500 mm from the ground. The choke, ignitor, capacitor and control fuse for each light fitting shall be installed within this compartment. Each pole shall be planted at a depth of not less than 1,500 mm deep.

The lighting around the fruit-loading ramp shall be provided by 400W high pressure sodium vapour lamps installed on 8 meter galvanized mild steel poles. These poles shall be suitably positioned to provide the best lighting and shall be positioned such that it is least liable to be damaged by the trucks. The lights shall be controlled from the lighting board (LDB-1) at the Sterilizer station by switches installed near the ramp.

The position of all light fittings shall be determined on site by the Engineer.



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School lighting installations

The design of electrical installation, including lighting, for schools always have the following few factors as the fundamental design criteria:

1) Simple design

2) Low construction cost

3) Simple operation

4) Low maintenance cost

5) Easily obtainable spare parts

In lighting design for buildings, school lighting designs takes this factors to full use.

Most school buildings are used only during the day and throughout the year we have very bright days in this country. Apart from that, the architectural layout of most school building usually end up being provided with wide area of windows and long narrow corridors.

Due to these factors, the contribution of daylight has a considerable effect in the lighting design for school buildings. In fact the above factors should be utilized fully to obtain a maximum reduction in the number of light fittings that are needed to provide the necessary level of brightness at all time.

An optimized design can have a considerable impact in terms construction cost saving and will result in an installation that is simple to operate and with a reasonable degree safety, considering that the majority of occupants in the school are young children.

The most widely used types of light fittings in school buildings are the fluorescent types, and the most popular of them is the bare channel fluorescent type. This type has always been found to be the most suitable and economical choice for interior lighting.

Fluorescent lights have a good color rendering characteristics. They have longer life and are less susceptible to voltage fluctuations. They also has higher luminous efficacy (higher light output per watt of electricity consumed) than tungsten filament lamp, the nearest contender in terms of simple design and low construction cost.

Lighting installation for student hostel buildings more often utilize compact fluorescent fittings in combination with the conventional fluorescent tubes. This is because the compact fluorescent lamps can be blended easily with decorative luminaries while retaining most of the other advantages: energy saving, high light output per watt consumed, generate low heat and longer life.

In study bedrooms, maximum amount of light is needed over the study table while the room needs to have a feeling of warmth and comfort. Therefore this type of rooms have the compact fluorescent as the general lighting, and an adjustable desk lamp as the task lighting for the study tables.

Spaces with high ceiling like the multipurpose halls and gymnasiums need the type of lighting that require minimum maintenance. Therefore the popular practice is to use high performance lighting types of high pressure discharge lamp. The high performance criteria is very important here because the lamps not only need to be of high light output and less maintenance, but also need to have a good color rendering index because of the type of activities that are carried out in these building spaces.

The stages in multipurpose halls are provided with stage lighting which comprise of the fresnel spotlights, profile spotlights and cyclorama floodlights. The stage lighting luminaries are suspended from specially designed lighting barrels with a complete rigging system.

The stage lighting and the hall general purpose lighting are provided with separate controls. The stage lighting itself is provided with dimmer and programmable controls.

School complexes with student hostels and staff quarters are provided with road lighting along the access roads to the hostel and quarters buildings. The residential compound and carpark areas are also provide with suitable compound lighting and carpark lighting.



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Light switches installation

The installation of light switches and other electrical parts 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.

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

2) Where group switching are 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.

3) 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 (eg. daylight sensor) is also commonly utilized.

4) The grouping of the lights should be so arranged that they can 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.

5) Further control in the levels of lighting should 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 a 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.


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Emergency lights installation

The installation of self contained emergency lights is a statutory requirement in most countries. They need to be provided at strategic places throughout the building in order to aid the evacuation of the building occupants out of the building in the event of failure o the mains supply.

The need for these emergency lighting is real even during daytime because some internal corridors inside the building are actually too dark without some form of lighting. The emergency lights are meant to provide the minimum illuminance needed for a safe and orderly movement of the people.

The self contained emergency light fittings are usually installed at all exit routes and at all places where uninterrupted lighting is required. In the second situation this lights serve the dual functions of a fire related equipment and a normal lighting (with much reduced lighting level).

The emergency light fittings are connected to the essential supply of the building electrical system. This way the rechargeable storage battery is charged even during normal power failure (i.e. when the standby electrical generator is running).

The exact quantity and the exact locations of these emergency light fittings are usually recommended by the Fire Department. In practice, a licensed architect is required by law to submit the building design plans to the Fire Department for approval before the building construction commences.

The architect would need to incorporate these lighting into their fire protection design schemes in order to obtain the Fire Department’s approval.

This layout is part of what is normally called the “static fire protection”. Those services like the wet risers, etc are called active fire protection and they will need to be submitted by licensed professional mechanical engineers to the Fire Department after the passive fire protection schemes (submitted by the architects) have been approved.

Prior to the submission by the architect, the electrical engineer’s input may be requested by the architect with respect to the quantities and locations of the emergency lights. However this task has become so routine that the engineer’s advice on this aspect is rarely necessary.

After the approval has been obtained, the approved layout of the emergency lighting is binding and it has become an input and a minimum design requirement for the electrical engineer. She can add more of the emergency light fittings into the design, but she cannot omit or change what has been approved in the submitted drawings.

That is basically the principle.

In addition to the self contained emergency lights that are required by the fire department, some of the general lighting luminaries are also connected to the essential supply that has been backed by the standby generator. This is sometimes done to supplement the lighting provided by the self contained emergency lights.

More often, however, this is done to provide some level of general lighting that can allow normal work to continue even in the event of normal power failure. Of course power failures caused by fire conditions demand a different course of actions immediately from all the building occupants.

There is one more lighting component that is closely related to the self contained emergency lights, that is the “EXIT” sign.

The Exit signs are also required by law similar to the emergency lights. They must be provided at all exit doors of all buildings and all floors, and at each location where the fire emergency exit routes change direction.

Similar to the emergency lights, these components are included in the proposed static fire protection submitted by the architects to the Fire Department.

An approved layout of this fire component will become a minimum design requirement to the electrical engineer. She can add more of the lighted Exit signs, but she cannot reduce them or change them.

Like the emergency lights also, the Exit signs are self-contained, battery operated. The difference between the two is that the Exit signs are always on.

See pictures of electrical installations by visiting this post, Free electric installation pictures.

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Temporary lighting installation

A construction site’s temporary electrical installation must also provide adequate lighting for the activities that are carried out at a particular workspace whether indoor or outdoor. Arguably more important than the light levels, the temporary lighting installation should be sufficiently safe for use and provided with adequate protection to prevent electrical shocks.

xxxxxxx RELATED PICTURES: High mast flood lighting | Temporary site floodlights  xxxxxx

1) Wire cages to prevent against mechanical damage should protect temporary light fittings at the construction sites. Damaged light fittings not only result in the repair cost, but they also present risks of electrical shocks to workers using them or those who are nearby. Precautions must be taken against the danger of electrical fires that because of damaged light fittings or the temporary supply wiring.

2) The temporary wiring supplying the lighting circuits should be connected to the special lighting section on the temporary switchboard. These circuits should be protected by 100 mA RCD (residual current circuit breakers).

3) Festoon lighting should only be used strictly in underground shafts, wells and tunnels. When this type of lights are used, the lamp holders should only be the moulded-on, non-removable type (the lamp holders are bonded or moulded to the wiring cables) and the lighting supply voltage is 32 Volts or below.

4) Either the temporary wiring or the newly installed permanent wiring may supply lift shaft temporary lighting. However, the light fittings used should be properly guarded against accidental mechanical damage and they should only be connected to the wiring using a lighting plug and socket. These lights should be installed at intervals of less than nine meters along the vertical length of the lift shaft. The control of the lift shaft lighting should be by means of two-way switches located near the shaft access points.

5) Normal duty lighting circuits are installed to provide general illumination for work and allow safe movement inside and around the construction site.

6) The installation of wiring for the temporary lighting should be carried out with proper supports and fittings to allow for wiring cables to be routed in ways that minimize obstructions, which can results in damage to the luminaries and wiring. These damages can present shock risks to the works and possibilities of electrical fires.

7) The use of lighting circuits supplied at safe extra low voltage levels (SELV - voltages less than 50 volts ac or 120 volts dc) is highly recommended for working in confined spaces where workers faces high possibilities of frequent contacts with temporary electrical equipment and wiring.

8) An illumination level of 10 lux is adequate for general movement within a building under construction. As an illustration, one length of 100 meter festoon light string fitted with 20 nos 100 watt lamps at 5 meter intervals will give a 10 lux over a rectangular area of 25 meter x 30 meter.

Read more on site electricity at this post, Temporary Electrical Installations.

You can also see a few pictures of site floodlight at this post,  Temporary site floodlights.



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Lighting installation design

This post used to contain a sample need statement for office building lighting design. It was the kind of need statements that are provided to design-and-build contractors or turnkey contractors during the initial stage, when the contractor was invited to submit a proposal.

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 Hinged louvers for maintenance

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Photo 1: Recessed lighting

Need statements like this provide a basis to indicate the approximate scope of works and also the standard of installation required by the building owner of the proposed new building.

However, after analyzing the traffic to this blog, I realized that only very few visitors were interested in the content of this post.

When I uploaded the original post, I had an intention to use it as a starter post from which I could link up to more posts and pictures about lighting design and installations.

The sample need statement would not be changed since someone might need it.

Since there seemed to be little interest in the materials, I have made a decision to just use the article of the need statement as an anchor post to link up to pictures and other articles on lighting.

Because of that, the format of the need statement will not be of a need statement any more.

It will be more convenient and faster for me, however, to link up to other posts on lighting in this way.

I have tons of posts to upload to this blogs, but I usually don’t have enough time to write something about it.

I need a method that does not require too much time writing.

So as you scan through this post downward, you will see the links to other posts that contain more photos, diagrams or articles. Follow the link and then come back here for more links.

What I mean is that I will be adding more links to this post in future, using it as an anchor post for lighting designs and installations.

Internal Lighting installation

The illumination levels shall generally be in accordance with the IES Codes, CIBSE Code for Interior Lighting and Lighting Guide 3 (LG3) and the current practices.

As reference, the general installed illumination levels at some of the areas/rooms shall be as follows:

a) Office, reception areas, waiting areas: 300 lux
b) Computer rooms: 500 lux
c) Lecture / Teaching places: 300 lux
d) Circulation areas: 100 lux
e) Electrical / telecommunication switch rooms: 300 lux
f) Areas for rough work: 200 lux
g) Areas for medium work: 400 lux
h) Areas for fine work: 600 lux
i) Internal corridors: 100 lux
j) External corridors: 30 lux
k) Street / compound lighting: 15 lux
l) Multi purpose hall: 500 lux

The lighting systems shall be designed by arrangement of alternating circuits, proper grouping of lighting switches, separate switching etc. so that unnecessary light fittings can be switched off as desired.

Thus the concept of energy saving shall be considered in the lighting system design.

The luminaries shall generally be of the following types:

1. Air-conditioned areas – Recessed fluorescent fittings with full aluminum parabolic reflectors and louvers complete with hinge for easy maintenance or whichever is appropriate.

2. Non air conditioned areas – Recessed fluorescent or surface mounted fluorescent fittings with full aluminium parabolic reflectors and louvers complete with hinge for easy maintenance.

3. Computer / data processing rooms – Recessed fluorescent fittings with full aluminium parabolic reflectors and louvers complying with CIBSE LG3 or Cat. 2 whichever is appropriate, complete with hinge for easy maintenance.

4. Corridors – Suitable types of recessed or surface mounted fluorescent fittings with full aluminium parabolic reflectors and louvers complete with hinge for easy maintenance, OR suitable type of recessed or surface mounted down lighter with energy saving discharge lamp, whichever is appropriate.

(Links: Hinged louvers for maintenance)

5. Store rooms / toilets – Suitable types of fluorescent fittings, OR suitable types of recessed down light with energy saving discharge lamp.

6. Meeting rooms / conference rooms – Same as office areas but supplemented by PAR down lights c/w dimmer.

7. Plant rooms – Suitable types of fluorescent fittings.

8. Other areas – Suitable types of light fittings.

9. Multi purpose halls – Suitable types of light fittings supplemented by PAR down lights c/w dimmers.

10. Walk path, garden and parks – Suitable types of foot path lantern c/w miniature PL/SL lamp with suitable height, controlled by time switch and/or photo-sensitive sensors whichever is appropriate.

11. Street / compound – Suitable type post with top or side entry SON fitting mounted on/in galvanized/ aluminium/ fiberglass/ composite die cast/ concrete R.C. poles of suitable height controlled by time switch and/ of photo-sensitive switch whichever is appropriate.

Luminaires for special requirements and areas:

1. Gallery/ exhibition/ showcase areas – Suitable decorative fitting, track lighting c/w ultraviolet filters to protect the exhibition materials.


Exit lights and self contained emergency lights of fluorescent type with three hours battery reserve shall be provided for all areas in accordance with the requirements of the Fire Department.

Suitable self contained emergency lights with sufficient lighting level for normal operation and with minimum three hours battery reserve shall be installed in staircases, public areas, electrical/ telecommunication switch rooms, riser rooms/ areas and other rooms/ areas in accordance with the requirements of the Fire Department.

Fluorescent tubes installed shall be of deluxe type with color temperature of approximately 4000 degrees K similar to Philips code 84. External street lighting, compound lighting and flood light shall be of SON type.

Lighting for walk paths shall be of miniature fluorescent lamps such as PL lamps. Ballast loss for fluorescent fitting and compact fluorescent / down lights shall be 6W loss. Insect fittings shall be installed at kitchen, cafeteria and other area as specified by Project Director/ Project Director Representative.

The common corridor, public areas etc. shall have two levels of illuminance (evening/ night) such that after midnight the lighting cab be reduced to a lower level.

The switching of these lights shall be by automatic time switches complete with 24 hours battery reserve and manual override or by other appropriate methods.

Depending on the functions of the department/ areas, some of the light fittings shall be connected to the essential circuits.

Suitable and adequate number of outdoor lighting with SON/ Metal Halide shall be provided for games courts such as badminton courts, squash courts, volley ball courts, etc.

External Lighting Installation

All works shall comply with the requirements, rules and regulations. They shall also follow the relevant latest circular for external lighting.

External lighting installations shall consists of Street Lighting, Compound Lighting, Garden/ Landscape Lighting, Sport Lighting, Area Floodlighting, Security Lighting, Fence Lighting, Façade Lighting, etc.

Compound/ street lighting shall be provided for the compound and internal roads within the compound of the project. The compound/ street lighting shall be mounted on galvanized/ aluminium/ fiber glass/ composite die cast poles/ concrete R.C. poles not exceeding 3.0 meters in height for compound lighting and 8.0 meters for street lighting. Wall mounted light fittings shall be used where pole mounted light fittings are not suitable.

Generally, the spacing between the poles shall not exceed three times the mounting height of the pole. The lamps for the light fittings of SON type. The illumination level on the ground/ road surface shall not be less than 1.5 lumens.

Suitable path lighting with PL lamps shall be provided in the parks and gardens and at the walk paths.

Suitable lightings shall be provided for guardhouse, signage, front fencing, etc.

Area floodlight shall be provided where necessary.

Suitable lighting with SON/ Metal Halide lamps shall be provided for games courts such as tennis court, badminton courts, volley ball courts, etc. The light fittings shall be on hot dipped galvanized steel poles/ concrete R.C. poles with climbing rungs and easy maintenance, etc.

All external compound/ street/ flood/ path lightings shall be provided with time switches and manual bypass or by other appropriate methods for automatic and manual switching. The lighting systems shall be of such design so that after midnight the lighting levels can be reduced if required.

Façade lighting consisting of floodlights, directional lights, etc. shall be provided to enhance the façade of the buildings.

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Light fitting specification

The following provides an example specification that can be used in a contract for the installation of the light fittings in a multi-storey office building.

General
All light fittings shall be designed to prevent ingress of vermin, accidental contact with any live part and to minimize the ingress of dust and dirt. Materials which may be liable to be attacked by termites or other insects shall be avoided.

All outdoor fittings shall be vandal, corrosion, rust-protected and fully weatherproof by means of carefully chosen materials, protective painting and sealing, gasketing and the application of protective compounds.

Each fitting shall be constructed and erected as to be easily accessible for inspection and maintenance.

Each fitting shall be complete with bulbs, tubes, control gears, suspension rods or chain, fixing brackets etc.

Terminals and contacts, as far as possible, shall be shielded as to afford protection from accidental contact. All terminals shall be suitable for connection with metal conduit, to meet with fire regulations.

Sample of each type of fittings must be submitted to the S.O. for approval prior to commencement of manufacture and/or installation.

Uniformity
All fittings, accessories and components in any items supplied shall be uniform of their type, similar parts being interchangeable.

Incandescent lamps
Tungsten filament lamps shall be of bayonet cap general service pattern, internally frosted and shall be suitable for operating on a 240/250 volts A.C. system. The ratings shall be as stated in the drawings.

Fluorescent lamps
All fluorescent tubes shall be of the standard 26mm diameter energy saving type having a color temperature of approximately 6200 degree K (daylight color) if not otherwise stated with, bi-pin lamp cap.

Unless otherwise specified, all fluorescent tubes shall be of switch-start type.

Compact fluorescent lamps
Where SL lamps are specified, they shall be the type of fluorescent lamp integrated with low pressure gas discharge ballast and starter and with Edison screw lamp cap (B22). The wattage of the lamps shall be 9, 13 or 18 as specified in the drawings.

Where PL lamps are specified, they shall be of the type with unique single-ended fluorescent lamps with two pin connection with instant start adapters. The lamp base shall be incorporated with capacitor. The lamp wattage shall be 7, 9, 11, or 13 as specified in the drawings.

Discharge lamps
Where gas discharge lamps are specified, they shall be the type with good color rendering and complete with necessary control gear such as ballasts, capacitors and igniters. The ratings of the lamps shall be as specified in the drawings.

Fluorescent lamp lighting fixtures
All fixtures must be fabricated by manufacturers registered with Director General of Electrical Department, and be approved with The National Testing Department.

The housing, base frame, cover plates and reflector of the fixtures shall be constructed of sheet steel of a thickness not less than 20 SWG.

The sheet steel body shall be designed such that it can be fixed to ceiling or the surface by suspension or on a separate detachable tray.

An adequate mains input terminal block marked “L” and “N” together with a substantial earthing terminal shall be riveted, welded or brazed to the base frame.

Retractable type spring load lamp holders fitted with lamps cap earthing contact housed in a white plastic moulding shall be suitable for direct attachment to the base frame.

All materials liable to corrosion shall be suitably protected and sheet steel surfaces shall be prepared, painted and finished white in stove or vitreous enamel.

Ballasts shall be of the switch start, vacuum/pressure impregnated in polyester resin type comply to B.S. 2818 Part1 or MS. 141: 1973. They shall be compact in design and silent in operation and of the “low loss” type with losses not exceeding 6.5 watts. One ballast shall be used to control one fluorescent tube only.

All capacitors for power factor correction shall be suitable for operating on 250 volts, single phase, 50 Hz at a temperature between -10 degree to 100 degree Centigrade and shall ensure a power factor of not less than 0.85 lagging.

Starter switch shall be of the two pin small metal canister glow type.

All internal wiring shall be heat resistant type and suitably identified by color coding and shall be neatly arranged and adequately supported.

All diffusers, unless otherwise stated, shall be made from tough translucent prismatic plastic of UV-stabilized polystyrene of not less than 2.5mm thick and free from blemishes.

All louvered diffusers, unless otherwise stated, shall be made from UV-stabilized polystyrene material with silver-metallized and parabolic 13mm x 13mm x 11mm cells.

All diffusers and louvered diffusers shall be mounted onto the steel frame which hinged onto the frame work of the fixtures and form a detachable dustproof cover.

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