LIGHTING SYSTEM
CONTENT
• Introduction
• Determining Lighting Requirements
• Selecting Lighting Fixtures
• Calculating Number of Lighting Fixtures required.
• Determining Lighting fixture location
• Creating the lighting plan
• Including keynotes sections
• Complying with energy code requirements
INTRODUCTION
The goal of lighting design is to develop a high quality lighting system that meets a facility’s
lighting needs while adhering to strict mandated energy codes that limit the amount of power a
facility can use for the lighting system.
 Determine the facility’s lighting requirements.
 Select appropriate lighting fixtures.
 Calculate the necessary number of lighting fixtures to meet lighting requirements.
 Determine the spacing of lighting fixtures throughout the facility.
 create lighting design.
 Noting all the branch circuits, raceways, switches & sensors to meet lighting & energy code
requirements.
Determining Lighting
Requirements
As per IEC NA Foot
candles(illumination level) required
by each area varies based their
nature of usage of area.
Here are some areas with required
foot candles as per IEC NA.
SELECTING LIGHTING FIXTURES
 Based on Area of classification.
(i) Some environments can pose difficult conditions for operating lighting
systems, including damp and wet areas, corrosiveenvironments,
hazardous locations, areas that experience abnormal temperatures,
areas that experience momentary power failures, and clean rooms.
That means that either the light source must be able to operate
properly under these conditions or the fixture must protect the light
source from these conditions.
(a) Damp And Wet Areas:
If the environment exposes the lighting system to moisture
condensation, then the location is a damp location
If the lighting system is exposed to direct impact by water,
which will make the fixture wet, then the location is a wet location.
(b) Corrosive Environments:
Some environments contain fumes and vapours that corrode
fixtures and supplementary components such as mounting hardware.
(c) Hazardous Locations:
In hazardous environments, the air contains flammable dust,
gas or vapours that can combust if it comes into contact with electrical
equipment, including lighting systems.
HAZARDOUS ENVIRONMENTS
Section 500 classifies hazardous locations as Class I, II and III; each class represents
two divisions, 1 and 2. Approval is gained by the local authority who has jurisdiction
in interpreting the NEC.
Below is a general information guide concerning fixtures in fixed locations only; when
designing a lighting system for hazardous locations, consult the NEC and all local
authorities with jurisdiction over building construction.
(i) Class I, Division 1 locations (NEC Section 500-5(a)) are environments
where flammable vapours or gases (or a combustible mixture of them) result from
normal operating conditions, repair or equipment breakdown. Fixtures designed for
approved use in these locations are explosion-proof, completely enclosed to 1) prevent
the escape or arcs or sparks that could ignite the flammable environment and 2)
contain an explosion of a gas or vapor inside them.
(ii) Class I, Division 2 locations (NEC Section 500-5(b)) are environments where
flammable gases or liquids are stored in tanks or other enclosed containers, and would
be released only if the containers were damaged. Fixtures designed for approved use in
these locations are enclosed and gasketed.
(iii)Class II, Division 1 locations (NEC Section 500-6(a)) are environments where
combustible dust is present or where dust may produce a combustible mixture
under normal operating conditions, or where equipment breakdown may produce
such a mixture. The NEC establishes a maximum limit on volt-amperage and size
of lamp for these locations. The fixture must be dust-ignition-proof and approved
for use.
(iv) Class II, Division 2 locations (NEC Section 500-6(b)) are environments
where combustible dust is not produced during normal operation but may result
from breakdown or other possible abnormal conditions. Fixtures designed for
approved use in Class II, Division 2 locations are tightly enclosed and gasketed to
prevent escape of arcs or sparks.
(v) Class III, Division 1 locations (NEC Section 500-7(a)) are environments
where combustible fibers are produced by normal operating conditions. Fixtures
designed for approved use in Class III, Division 1 locations are tightly enclosed
and gasketed to prevent escape of arcs or sparks
(vi) Class III, Division 2 locations (NEC Section 500-7(b)) are environments
where combustible fibers are handled or stored. Fixtures designed for approved use
in Class III, Division 2 locations are tightly enclosed and gasketed to prevent
escape of arcs or sparks.
Areas That Experience Abnormal Temperatures
The starting and operation of fluorescent and high-intensity discharge (HID) lighting
systems can be affected by abnormal temperatures.
In low-temperature environments such as refrigerated areas, fluorescent lamps can
experience adverse performance such as "fluttering," reduced light output and
difficulty starting by the ballast. In such applications, enclosed fixtures, special "cold
weather" fluorescent lamps and/or jacketed lamps can help ensure reliable performance;
in addition, fixtures can be located a suitable distance from cold-air source units. Cold
weather ballasts that can start the lamps at temperatures below 0°F should be specified
for applications where the ambient temperature is expected to be below 50°F. Cold
weather electronic and magnetic ballasts can be specified for HO and VHO lamps that
can start them at temperatures as low as -20°F. See the Table below for minimum
starting temperatures for a variety of fluorescent ballasts. HID lamps can start in a
wide range of ambient temperatures.
Table. Minimum Starting Temperatures for Typical Fluorescent Ballasts
Ballast
Typical Minimum Starting
Temperature
Magnetic w/T8 lamps
+50°F
Magnetic w/standard T12 lamps
+50°F, 0°F
Magnetic w/energy-saving T12 lamps
+60°F
Magnetic w/HO or VHO T12 lamps
+50°F, 0°F, -20°F
Hybrid* w/standard T12 or T8 lamps
+50°F
Hybrid w/energy-saving T12 lamps
+60°F
Electronic w/2, 3 & 4 ft. T8 lamps
+50°F, 0°F
Electronic w/standard T12 lamps
+50°F, 0°F
Electronic w/energy-saving lamps
+60°F
Electronic w/8 ft. "Slimline" T8 lamps
+50°F
Electronic w/HO T12 lamps
+50°F, 0°F, -20°F
*Also called a cathode cut-out ballast
• High Temperature Areas: In areas experiencing high ambient temperatures, the
ballast can overheat. Class P ballasts contain a thermal protection device that
disconnects the ballast from the power source if it begins to overheat. The ballast
then cools until an automatic resetter reconnects it to the power supply. If the
overheating is not corrected, the process, called "cycling," will repeat itself. In
addition, if the temperatures are high enough, ballast life could be shortened and
light output reduced.
• High Ambient Temperature Areas: Fixtures in areas experiencing high ambient
temperatures should be well-ventilated. In such fixtures, the heat produced by the
lamps generates convection currents that remove the heat. Special HID ballasts can
be specified that are designed to operate under high ambient temperatures, or the
ballast can be located at a remote location (the distance subject to limitations).
Medium bay metal
halide lamp
Fluorescent lamp
High bay metal
halide lamp
Calculation for required no. of fixtures
To calculate the number of fixtures required for an office with the following specifications:
• Dimensions of 25.5 ft x 16.5 ft
• Desired illuminance level of 30fc.
• Fluorescent lighting fixtures with three fluorescent lamps, each with an output of 2850 lm.
1.
Calculate the total area of the space to be illuminated (A):
25.5 ft x 16.5 ft = 420.75sq.ft
2.
Determine the total lumen output of the lamp(s) (FL):
No. of lamps within the lighting fixture x lumen output per each lamp.
3 lamps x 2850lm each = 8550 lm
3.
Determine the light loss factor (LLF):
LLF = 0.79 (standard value for typical Commercial office space.)
4.
Determine the co-efficient of utilisation(Cu):
Cu = 0.67 (typical value-consult manuf. Catalog for more exact numbers)
5.
Substituting the above in the below equation:
No. of lighting fixtures required = FC x A .
FL x LLF x Cu
= 30 x 420.75 = 2.79
8550 x 0.79 x 0.67
6. Round up to the next whole no. to determine the total no. of fixtures required.
Ans: With the provided specifications and fixtures, this room requires three lighting fixtures.
Illumination (E): It is defined as the ratio of Flux to the area
Lumen: Lumen is defined as the amount of luminous flux radiated from the lamp.
The measurement of the total amount of light output from a lamp is called lumen.
It is also defined as the flux /unit angle from a source of 1 candle power.
Luminous intensity : The amount of light output (in lumens) falling on unit
square meter of surface (illuminance) is called as light intensity. The unit of light
intensity is Lux.
Lux or (Foot candles) = Lumens / Area in sq.m or (sq.inch)
Determining Lighting fixture location
Based on the location of fitting i.e., spacing of two fixtures / fixture & wall /
Fixture from the working plane (mounting height from the ceiling) average
illumination varies. Hence By placing the fixture at appropriate location the
average illumination level required is achieved with reduced/minimum number
of fixtures.
•To determine lighting fixture location for fixtures with the following specifications:
•Lighting fixtures to be mounted in a ceiling 9 ft above the floor
•Work surface to be illuminated located 2.5ft above the floor
•Lighting fixture with a row multiplier of 1.25 and a column multiplier of 1.37
1. Determine the distance from the mounting height to the work surface:
9ft – 2.5ft = 6.5ft
2. Multiply this distance by the row and column multipliers:
•Row : 6.5ft x 1.25 = 8.13ft
•Column : 6.5ft x 1.37 = 8.91 ft
Ans : The lighting fixtures should be mounted with an end to end dimension of approximately 8 ft
and a side to side dimension of approximately 9 ft.
Creating the Lighting Plan
To design a lighting plan, the designer requires floor plans or reflected ceiling plans
from the architect.
These plans illustrate the ceiling types such as acoustical title type ceiling or drywall
ceiling for the space to be designed.
This information is necessary for the designers to choose the proper types of lighting
fixtures and their mounting methods. Designing lighting and power plans on
different sheets allows for better clarity. The detailed elements that are typically
found on lighting plans are the following:
1. Lighting fixture schedule.
2. Branch circuit identification.
3. Control devices ( eg.., switch, sensor) type and location.
4. Raceway location.
5. Keynotes.
Lighting Fixture schedule:
Lighting Fixture schedule:
Designers create a lighting fixture schedule in the design plan to relay all the
relevant lighting fixture details. Lighting fixture schedules list the following
information for each fixture:
1. Identification (alphanumerical reference)
2. Power rating in volt amperes
3. Type of lighting fixture (e.g., flush mount, acoustical title grid mount, high bay).
4. Lamp type and quantity within the fixture.
5. Lighting fixture input watts
6. Mounting method (e.g., recess mounted, surface mounted, pendant mounted,
wall mounted).
7. Brief description of the type of lighting fixture and variations.
8. Lighting fixture manufacturer name.
9. Manufacturer catalog numbers for lighting fixture types.
Branch circuits identification
Branch circuits:
1. After the lighting fixtures for a particular project are designed, the designer must calculate
the required number of lighting branch circuits necessary to serve the lighting system.
Then, the designer can determine which branch circuit will serve each lighting fixture and
identify the lighting branch circuit at each lighting fixture location. This identification
provides a reference for the field installer, who needs to identify which lighting branch
circuit is to serve the fixture.
Maximum allowable volt-ampere rating for lighting Branch circuits:
1. The first step in determining the required number of lighting branch circuits is for the
designer to calculate the maximum allowable volt ampere rating for each of the lighting
branch circuits that will serve the lighting system.
2. Serving voltage of the lighting system.
Number of required lighting branch circuits:
Once the serving voltage for the lighting system and the maximum allowable volt ampere
rating are determined, the designer can calculate the minimum quantity of required
branch circuits for lighting loads.
Control devices:
All fixtures in a narea must have control devices to turn them on and off. To meet energy
saving requirements, lighting systems are now required to include specialized control
methods such as occupancy sensors that automatically turn off lighting fixtures after a
predetermined amount of time.
Control Devices
Occupancy sensors work by sensing motion in a room, and they turn off lights after a preset
amount of time when they detect no motion, thereby reducing energy consumption.
Designers calculate the number of sensors required for a space based on the dimensions of
the area and manufacturer specifications on the sensing range of the sensors.
For more advanced lighting design, programmable lighting controllers can be installed to
provide more sophisticated lighting control. these sensors allow the lighting system to be
reprogrammed as the area’s needs change.
In the areas where programmable controllers are used, designers must include additional
bypass switches so that personnel in the area can access lighting when the program has
shut down the system. With bypass switches, personnel can turn on lighting fixtures
individually in the spaces they need to occupy without illuminating the entire area, which
reduces lighting energy consumption.
Types of Occupant Sensors
Types of Occupant sensors are
1.
Passive Infrared (PIR) sensors
2.
Ultrasonic sensors
Occupancy sensors
Occupant sensors are switching devices that respond to the presence and absence of people in
the sensor’s field of view.
The system consists of a/an
1. Motion detector
2. Electronic control unit
3. Controllable switch (relay).
Low voltage
Line
voltage
Transformer
(power
supply)
Relay
Luminaire
Controller
Sensor
Day lighting and lumen maintenance
The term “day light control” reveals the relationship between electric light and the presence or
absence of daylight in area to be lighted.
Since the daylight is present in many spaces of the area for many hours of the day,
photoelectrically controlled lighting systems have considerable potential for reducing
lighting energy usage.
Lumen maintenance also relies on a photo- electrically linked lighting system. Lumen
maintenance saves energy by limiting input power when lamps are new and fixtures clean.
(when new and clean, lighting systems produce more lumens for less input watts than
when they are at the end of their maintenance cycle).
As the control photosensors detect the gradual drop in electric lighting efficiency, the control
system automatically provides just the right light level to meet design requirements.
Advantages on the usage of day lighting sensors:
1.
2.
3.
4.
Daylighting costs nothing, and can be used to supplement, or even, in some cases, replace
electric light.
Day light is the most complete and “natural” colour spectrum light source available.
Daylighting can allow occupants a greater connection to the outdoor environment.
Research on worker productivity has suggested a link between daylight in the work
environment and a general sense of psychological well being.
Daylight design increases interest in the visual environment.
Determining Maximum Volt-ampere
ratings for Lighting branch circuits:
To determine the maximum volt-amperage for a lighting branch circuit with the following
specifications:
•277V or 120V branch circuit
•20A branch circuit rating..
•Use the following formula::
•Supply voltage x size of the branch circuit over current protective device (typically 20A) x 80
percent
1.
For a 277 V lighting branch circuit:
277 V x 20 A x 0.8 = 4432VA
Ans: For the serving voltage , the maximum allowable volt amperes that could be served for
each 20 A lighting branch circuit is 4432VA.
2.
For a 120 V lighting branch circuit:
120 V x 20 A x 0.8 = 1920VA
Ans: For the serving voltage , the maximum allowable volt amperes that could be served for
each 20 A lighting branch circuit is 1920VA.
Determining the number of required
Lighting branch circuits:
To determine the minimum number of required lighting branch circuits for a design with the following
specification:
•Total combined lighting volt ampere rating of 12650VA ( based on lighting fixture quantities and
the sum their individual volt ampere ratings
•277V, 20A lighting branch circuit .
1.
Calculate the maximum ratings using the formula given previously:
277 V x 20 A x 0.8 = 4432VA
2.
Divide the volt ampere total for all lighting fixtures to be installed by the total allowable volt
ampere rating for the lighting branch circuit:
12650 VA / 4432 VA = 2.85 branch circuits
Ans: A minimum of 3 lighting branch circuits is required.
Lighting Branch Circuit Raceways
The lighting design plan must illustrate which switching devices control which
lighting fixtures and the location of the switching devices. Designers must illustrate
all the control devices to the lighting fixtures and their respective raceways on the
lighting plan. The lighting branch circuit raceway layout should illustrate the
following information:
1. Control device locations.
2. Which lighting fixtures controlled by which device.
3. Number of conductors within the raceway.
Key Notes
Interpreting Energy Code design methods:
Designers can employ various methods to meet energy code requirements, depending
on the details and needs of the project. The least complex method of lighting design is
the Complete building method.
This method uses an allowable power density value to compute the lighting energy
level evenly throughout the whole building.
For example, in a 5500sq.ft commercial building with an energy allowance of
1.1W/sq.ft, the lighting system cannot exceed 6050W (5500sq.ft x 1.1 W/ sq.ft).
Energy allowances vary based on location and jurisdiction
Q& A
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