Resistive-type heating appliances and incandescent lamps (conventional or halogen)

See also "Lighting circuits" for more details

The current demand of a heating appliance or an incandescent lamp is easily obtained from the nominal power Pn quoted by the manufacturer (i.e. cos φ = 1) (see Fig. A5).

Fig. A5 – Current demands of resistive heating and incandescent lighting (conventional or halogen) appliances

Nominal power (kW)	Current demand (A)
	1-phase 127 V	1-phase 230 V	3-phase 230 V	3-phase 400 V
0.1	0.79	0.43	0.25	0.14
0.2	1.58	0.87	0.50	0.29
0.5	3.94	2.17	1.26	0.72
1	7.9	4.35	2.51	1.44
1.5	11.8	6.52	3.77	2.17
2	15.8	8.70	5.02	2.89
2.5	19.7	10.9	6.28	3.61
3	23.6	13	7.53	4.33
3.5	27.6	15.2	8.72	5.05
4	31.5	17.4	10	5.77
4.5	35.4	19.6	11.3	6.5
5	39.4	21.7	12.6	7.22
6	47.2	26.1	15.1	8.66
7	55.1	30.4	17.6	10.1
8	63	34.8	20.1	11.5
9	71	39.1	22.6	13
10	79	43.5	25.1	14.4

The currents are given by:

• 3-phase case: [math]\displaystyle{ \mbox{Ia}=\frac{\mbox{Pn} }{\sqrt3\mbox{U} } }[/math] 
• 1-phase case:[math]\displaystyle{ \mbox{Ia}=\frac{\mbox{Pn} }{\mbox{U} } }[/math] 

where U is the voltage between the terminals of the equipment.

For an incandescent lamp, the use of halogen gas allows a more concentrated light source. The light output is increased and the lifetime of the lamp is doubled.

Note: At the instant of switching on, the cold filament gives rise to a very brief but intense peak of current.