Lighting - Lamps
Electric Lamp Patent by Edison, 1880
Image Source: ourdocuments.gov Lamps are the essential part of any luminaire. These are the light generating components. Since the advent of electrical lighting in the middle of the 19th century, multiple types of lamps have been developed. Over the years lamp technology continues to evolve offering increases in performance and efficiencies.
Lamp Types
Filament Lamps
Electricity heats a filament until it is incandescent (around 2800 K).
- General Lighting Service Lamp, GLS - designed for general lighting service with tungsten filament surrounded by inert gas and enclosed in a glass bulb.
- Tungsten-halogen, TH - use of halogen vapour allows a higher operating temperature and increased efficacy
Discharge Lamps
Ionisation of a gas (or metallic vapour), initially by the application of an high voltage pulse followed by charged particles colliding with atoms. This causes radiation to be given off.
- Low pressure lamps - have relatively long distances between collisions allow charged particles to build up sufficient speed to cause excitation
- High pressure lamps - an increase in the number of collisions (due to a denser arrangement of atoms) causes sufficient heat to raise the temperature of the gas
- Fluorescence - low pressure mercury discharge produces ultra-violet radiation, converted to visible light by fluorescent or phosphor coating
Sarters (Ballasts)
Discharge lamps require starters to enable a high voltage to be applied to the lamp during starting , while limiting the current flowing once the gas has become ionised. Possible starters include:
- Resistance - can limit current flowing, not used due to large heat dissipation
- Reactance - can limit current flowing, commonly used
- Capacitance - can limit current flowing, only used on rare occasions
- Ignitor - generates series of high voltage pulses, staring of lamps at voltages higher than mains
- Reactance autotransformer - provides higher than mains stating voltage, limits operation current
- Glow starter - closes or opens the pre-heating circuit of a fluorescent tube
- Electronic starter - device for fluorescent tubes to provide necessary pre-heating of the electrodes
Modern Technology
Recent drives to create more efficient and environmentally friendly lamp technology has see much research and development in the fields of LED and Induction Lamps.
- LED (Light Emitting Diode) - electric current flowing through a semi-conductor junction cause light to be emitted.
- Induction Lamp a high frequency electromagnetic field is injected is used to excite mercury, producing UV radiation and phosphor coating converts to visible light
Summary of Lamp Characteristics
Lamp |
Description |
Watts
W |
Efficacy
lm W-1 |
Life (hours)
1000's |
Colour |
Typical
Application |
| CCT |
RG |
Class |
| Filament |
| GLS |
General lighting service
|
25 to 1000
|
8 to 18
|
1 to 2
|
2800
|
1A |
Warm |
Home |
|
TH
|
Tungsten halogen
|
25 to 1500
|
18 to 24 |
2 to 4
|
2900 |
1A |
Warm |
Display |
| Tubular Fluorescent |
|
T5
|
15 mm diameter |
4 to 80 |
37 to 94 |
1 to 4 |
2800 to 6500 |
1A,1B,2,3 |
All |
Factory, office & shops
|
| T8 |
26 mm diameter |
18 to 70 |
75 to 93 |
1 to 1.5 |
As above |
As above |
All |
|
| T12 |
38 mm diameter |
|
|
|
As above |
As above |
All |
|
| Sodium |
|
SOX
|
Low pressure
|
10 to 135
|
100 to 200
|
6 to 20
|
None |
|
|
Roads |
|
SON
|
High pressure |
50 to 1000
|
70 to 130
|
6 to 24
|
2000 to 2200 |
2,4 |
Warm |
Industry |
| Mercury |
| MBF |
High pressure |
50 to 1500
|
35 to 55
|
5 to 24
|
3800 |
3 |
Intermediate |
Industry |
| MBTF |
High pressure blended (MBF+filament) |
50 to 1500
|
|
|
|
|
|
|
| Metal halide |
| MBI |
High pressure discharge |
70 to 1000
|
65 to 85
|
5 to 12
|
5200 |
2 |
Intermediate |
Industry, commerce |
If your looking for a good (more detailed) comparison of technical parameters across all lamps, the Thorn Technical Handbook is a good resource (freely available online)
Typical Currents & Recommended Fuse/MCB Ratings
| |
Current (A) |
Fuse/MCB (A) for No.Lamps |
|
Watt |
μF |
Start |
Run |
1 |
2 |
3 |
4 |
5 |
6 |
|
SOX
|
18
|
|
|
|
4
|
4
|
4
|
4
|
4
|
4
|
|
SOX
|
35
|
|
|
|
4
|
4
|
4
|
4
|
4
|
4
|
|
SOX
|
55
|
|
|
|
4
|
4
|
4
|
4
|
4
|
4
|
|
SOX
|
90
|
|
|
|
4
|
4
|
4
|
4
|
6
|
6
|
|
SOX
|
135
|
|
|
|
4
|
10
|
10
|
16
|
20
|
25
|
|
SON
|
50
|
|
0.35
|
0.3
|
4
|
4
|
4
|
4
|
4
|
4
|
|
SON
|
70
|
|
0.55
|
0.4
|
4
|
4
|
4
|
6
|
6
|
10
|
|
SON
|
100
|
|
0.7
|
0.52
|
4
|
4
|
4
|
6
|
10
|
10
|
|
SON
|
150
|
|
0.7
|
0.8
|
4
|
6
|
10
|
10
|
16
|
16
|
|
SON
|
250
|
|
1.5
|
1.3
|
10
|
16
|
16
|
20
|
20
|
20
|
|
SON
|
400
|
|
3.0
|
2.15
|
16
|
20
|
20
|
25
|
25
|
32
|
|
SON
|
1000
|
|
6.0
|
5.4
|
20
|
25
|
32
|
40
|
50
|
63
|
|
MBF
|
50
|
6
|
0.32
|
0.3
|
4
|
4
|
4
|
4
|
4
|
4
|
|
MBF
|
80
|
8
|
0.5
|
0.4
|
4
|
4
|
4
|
4
|
6
|
6
|
|
MBF
|
125
|
8
|
1.1
|
0.7
|
4
|
4
|
6
|
10
|
10
|
10
|
|
MBF
|
250
|
13
|
2.2
|
1.33
|
10
|
16
|
16
|
20
|
20
|
20
|
|
MBF
|
400
|
20
|
4.0
|
2.2
|
16
|
20
|
20
|
25
|
25
|
25
|
|
MBF
|
700
|
20
|
6.5
|
3.5
|
16
|
20
|
25
|
32
|
32
|
40
|
|
MBF
|
1000
|
50
|
9.0
|
5.5
|
20
|
25
|
32
|
40
|
50
|
63
|
|
MBI
|
150
|
20
|
0.76
|
0.76
|
4
|
6
|
10
|
10
|
16
|
16
|
|
MBI
|
250
|
30
|
1.5
|
1.3
|
10
|
16
|
16
|
20
|
20
|
20
|
|
MBI
|
400
|
25
|
3.5
|
2.0
|
16
|
20
|
20
|
25
|
25
|
25
|