The following table (compliments of
Schneider Electric) gives recommended
circuit breaker ratings for use in circuits
with discharge lamps. Ratings are based
on the time current characteristics of type
C and D circuit breakers.
PROTECTION OF LAMP CIRCUITS
During start up of discharge lamps, surge
current maybe in the order of:
- 25 x circuit start current for the first 3
milliseconds. 7 x circuit start current for
the following 2 seconds. Circuits with
long cable runs may reduce the actual
inrush current due to the voltage drop to
a level which is lower than the maximum
of 25 x start up current. This could effect
the choice of circuit breaker rating used
in circuits where the number of lamps
exceed 3, a reduced surge current factor
is therefore applied. Consideration must
be given to the number of lamp fittings
used in each circuit as this may entail the
use of unusually large cable.
High Pressure Sodium (HPS), Metal Halide - Type D Circuit Breaker Rating
Lamp Wattage (W)
Max number
of luminaires
per phase
Circuit Current (A)
Start
Run
70w
150w
250w
400w
1000w
6
9
18
25
6
9
18
25
2
4
8
12
2
3
6
9
1
2
4
6
0.55
0.40
1.00
0.80
1.50
1.30
3.00
2.15
6.00
5.40
MCB
Contactor
Rating (A)
Rating (A)
16
25
40
63
25
40
40
63
Fluorescent lamp with conventional ballast - Type C
Lamp Wattage (W)
Max number
of luminaires
per phase
2x18w
2x36w
22
30
46
61
78
97
122
153
180
12
15
23
30
39
49
61
77
100
4x36w
6
7
11
14
19
24
30
38
50
1x58w
13
16
20
35
42
56
65
84
110
MCB
Contactor
2x58w
Rating (A)
Rating (A)
7
11
16
19
25
31
39
49
63
10
16
20
25
32
40
50
63
100
16
25
25
40
40
63
63
100
100
MCB
Contactor
2x58w
Rating (A)
Rating (A)
7
10
16
19
24
31
38
46
75
10
16
20
25
32
40
50
63
100
16
16
25
25
40
40
63
63
100
Fluorescent lamp with Electronic Ballast, 230v Halogen or
Tungsten Filament - Type C
Lamp Wattage (W)
Max number
of luminaires
per phase
2x18w
2x36w
22
30
46
55
78
97
122
150
225
12
19
23
30
39
49
60
77
120
4x36w
6
7
11
14
19
24
30
38
60
1x58w
13
16
33
35
49
62
77
90
150
Further info on request · email: info@veelite.com · www.veelite.com
Circuits with large numbers of lamp
fittings may cause some inconvenience
in the event of a fault, as due regard for
safety in the working enviroment must
be considered in the event of the lighting
being extinguished.