Discharge lamps

See also "Lighting circuits" for more details

The power in watts indicated on the tube of a discharge lamp does not include the power dissipated in the ballast.

Figure A8 gives the current taken by a complete unit, including all associated ancillary equipment.

These lamps depend on the luminous electrical discharge through a gas or vapour of a metallic compound, which is contained in a hermetically-sealed transparent envelope at a pre-determined pressure. These lamps have a long start-up time, during which the current Ia is greater than the nominal current In. Power and current demands are given for different types of lamp (typical average values which may differ slightly from one manufacturer to another).

Fig. A8 – Current demands of discharge lamps

Type of lamp (W)	Power demand (W) at		Current In (A)				Starting		Luminous efficiency (lumens per watt)	Average timelife of lamp (h)	Utilization
			PF not corrected		PF corrected		x In	Period (mins)
	230 V	400 V	230 V	400 V	230 V	400 V
High-pressure sodium vapour lamps
50	60		0.76		0.3		1.4 to 1.6	4 to 6	80 to 120	9000	Lighting of large halls Outdoor spaces Public lighting
70	80		1		0.45
100	115		1.2		0.65
150	168		1.8		0.85
250	274		3		1.4
400	431		4.4		2.2
1000	1055		10.45		4.9
Low-pressure sodium vapour lamps
26	34.5		0.45		0.17		1.1 to 1.3	7 to 15	100 to 200	8000 to 12000	Lighting of motorways Security lighting, railway stations platforms Platform, storage areas
36	46.5				0.22
66	80.5				0.39
91	105.5				0.49
131	154				0.69
Mercury vapour + metal halide (also called metal-iodide)
70	80.5		1		0.40		1.7	3 to 5	70 to 90	6000	Lighting of very large areas by projectors (for example: sports, stadiums, etc.)
150	172		1.80		0.88
250	276		2.10		1.35
400	425		3.40		2.15
1000	1046		8.25		5.30
2000	2092	2052	16.50	8.60	10.50	6				2000
Mercury vapour + fluorescent substance (fluorescent bulb)
50	57		0.6		0.30		1.7 to 2	3 to 6	40 to 60	8000 to 12000	Workshops with very high ceilings (halls, hangars) Outdoor lighting Low light output
80	90		0.8		0.45
125	141		1.15		0.70
250	268		2.15		1.35
400	421		3.25		2.15
700	731		5.4		3.85
1000	1046		8.25		5.30
2000	2140	2080	15		11	6.1

• Note : these lamps are sensitive to voltage dips. They extinguish if the voltage falls to less than 50% of their nominal voltage, and will not re-ignite before cooling for approximately 4 minutes.
• Note: Sodium vapour low-pressure lamps have a light-output efficiency which is superior to that of all other sources. However, use of these lamps is restricted by the fact that the yellow-orange colour emitted makes colour recognition practically impossible.