LED lamps - choice of circuit breaker

Choice of circuit-breaker for discharge and fluorescent lamps

Protection of lamp circuits: Maximum number of lamps and MCB rating versus lamp type, unit power and MCB tripping curve

During start up of discharge lamps (with their ballast), the inrush current drawn by each lamp may be in the order of:

• 25 x circuit start current for the first 3 ms
• 7 x circuit start current for the following 2 s

For fluorescent lamps with High Frequency Electronic control ballast, the protective device ratings must cope with 25 x inrush for 250 to 350 µs.

However due to the circuit resistance the total inrush current seen by the MCB is lower than the summation of all individual lamp inrush current if directly connected to the MCB.

The tables below (see Fig. N53 to N58) take into account:

• Circuits cables have a length of 20 meters from distribution board to the first lamp and 7 meters between each additional fittings.
• MCB rating is given to protect the lamp circuit in accordance with the cable cross section, and without unwanted tripping upon lamp starting.
• MCB tripping curve (C = instantaneous trip setting 5 to 10 In, D = instantaneous trip setting 10 to 14 In).

Lamp power (W)	Number of lamps per circuit
	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20
MCB rating C & D tripping curve
14/18	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6
14x2	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6
14x3	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	10	10	10
14x4	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	10	10	10	10
18x2	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6
18x4	6	6	6	6	6	6	6	6	6	6	6	6	6	10	10	10	10	10	10	10
21/24	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6
21/24 x 2	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6
28	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6
28x2	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	10	10	10
35/36/39	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6
35/36 x 2	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	10	10	10	10	10
38/39 x 2	6	6	6	6	6	6	6	6	6	6	6	6	10	10	10	10	10	10	10	10
40/42	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6
40/42 x2	6	6	6	6	6	6	6	6	6	6	6	10	10	10	10	10	10	10	10	16
49/50	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6
49/50 x2	6	6	6	6	6	6	6	6	6	6	10	10	10	10	10	10	16	16	16	16
54/55	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	10	10
54/55 x2	6	6	6	6	6	6	6	6	10	10	10	10	10	10	16	16	16	16	16	16
60	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	10	10	10	10

Fig. N53: Fluorescent tubes with electronic ballast - Vac = 230 V

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Lamp power (W)	Number of lamps per circuit
	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20
MCB rating C & D tripping curve
6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6
9	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6
11	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6
13	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6
14	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6
15	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6
16	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6
17	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6
18	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6
20	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6
21	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6
23	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6
25	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	10

Fig. N54: Compact fluorescent lamps - Vac = 230 V

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Lamp power (W)	Number of lamps per circuit
	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20
MCB rating C tripping curve
Ferromagnetic ballast
18	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6
26	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6
35/36	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6
55	6	6	6	6	6	6	6	6	6	6	6	6	6	10	10	10	10	10	10	10
91	6	6	6	6	6	6	6	6	6	10	10	10	10	10	10	10	16	16	16	16
131	6	6	6	10	10	10	10	10	10	10	10	10	16	16	16	16	16	16	16	20
135	6	6	6	10	10	10	10	10	10	10	10	16	16	16	16	16	16	20	20	20
180	6	6	10	10	10	10	10	10	16	16	16	16	20	20	20	20	25	25	25	25
Electronic ballast
36	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6
55	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6
66	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	10	10	10
91	6	6	6	6	6	6	10	10	10	10	10	10	10	10	10	10	16	16	16	16
MCB rating D tripping curve
Ferromagnetic ballast
18	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6
26	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6
35/36	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6
55	6	6	6	6	6	6	6	6	6	6	6	6	6	6	10	10	10	10	10	10
91	6	6	6	6	6	6	6	6	6	6	10	10	10	10	10	10	16	16	16	16
131	6	6	6	6	6	6	10	10	10	10	10	10	16	16	16	16	16	16	16	20
135	6	6	6	6	6	6	10	10	10	10	10	16	16	16	16	16	16	20	20	20
180	6	6	6	6	10	10	10	10	16	16	16	16	20	20	20	20	25	25	25	25
Electronic ballast
36	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6
55	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6
66	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	10	10	10
91	6	6	6	6	6	6	6	6	6	6	10	10	10	10	10	10	10	16	16	16

Fig. N55: Low pressure sodium (with PF correction) - Vac = 230 V

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Lamp power (W)	Number of lamps per circuit
	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20
MCB rating C tripping curve
Ferromagnetic ballast
50	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	10	10	10	10
70	6	6	6	6	6	6	6	6	6	6	10	10	10	10	10	10	10	16	16	16
100	6	6	6	6	6	6	6	6	10	10	10	10	10	16	16	16	16	16	16	16
150	6	6	10	10	10	10	10	10	6	16	16	16	16	16	16	20	20	20	25	25
250	6	10	16	16	16	20	20	20	20	20	20	25	25	25	32	32	32	32	40	40
400	10	16	20	25	32	32	32	32	32	32	32	40	40	40	50	50	50	50	63	63
1000	16	32	40	50	50	50	50	63	63	-	-	-	-	-	-	-	-	-	-	-
Electronic ballast
35	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6
50	6	6	6	6	6	6	6	6	6	6	6	6	6	10	10	10	10	10	10	10
100	6	6	6	6	6	6	6	6	10	10	10	10	10	10	16	16	16	16	16	16
MCB rating D tripping curve
Ferromagnetic ballast
50	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	10	10	10	10
70	6	6	6	6	6	6	6	6	6	6	10	10	10	10	10	10	10	16	16	16
100	6	6	6	6	6	6	6	6	10	10	10	10	10	16	16	16	16	16	16	16
150	6	6	6	6	6	10	10	10	10	16	16	16	16	16	16	20	20	20	25	25
250	6	6	10	10	16	16	16	16	16	20	20	25	25	25	32	32	32	32	40	40
400	6	10	16	16	20	20	25	25	25	32	32	40	40	40	50	50	50	50	63	63
1000	10	20	32	32	40	40	50	63	63	-	-	-	-	-	-	-	-	-	-	-
Electronic ballast
35	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6
50	6	6	6	6	6	6	6	6	6	6	6	6	6	10	10	10	10	10	10	10
100	6	6	6	6	6	6	6	6	10	10	10	10	10	10	16	16	16	16	16	16

Fig. N56: High pressure sodium (with PF correction) - Vac = 230 V

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Lamp power (W)	Number of lamps per circuit
	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20
MCB rating C tripping curve
Ferromagnetic ballast
35	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6
70	6	6	6	6	6	6	6	6	6	6	10	10	10	10	10	10	10	16	16	16
150	6	6	10	10	10	10	10	10	10	16	16	16	16	16	16	20	20	20	25	25
250	6	10	16	16	16	20	20	20	20	20	20	25	25	25	32	32	32	32	40	40
400	6	16	20	25	25	32	32	32	32	32	32	40	40	40	50	50	50	50	63	63
1000	16	32	40	50	50	50	50	63	63	63	63	63	63	63	63	63	63	63	63	63
1800/2000	25	50	63	63	63	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-
Electronic ballast
35	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6
70	6	6	6	6	6	6	6	6	6	6	6	6	10	10	10	10	10	10	10	10
150	6	6	6	10	10	10	10	10	10	10	16	16	16	16	16	16	16	20	20	20
MCB rating D tripping curve
Electronic ballast
35	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6
70	6	6	6	6	6	6	6	6	6	6	6	10	10	10	10	10	10	16	16	16
150	6	6	6	6	6	10	10	10	10	16	16	16	16	16	16	20	20	20	25	25
250	6	6	10	10	16	16	16	16	16	20	20	25	25	25	32	32	32	32	40	40
400	6	10	16	16	20	20	25	25	25	32	32	40	40	40	50	50	50	50	63	63
1000	16	20	32	32	40	50	50	63	63	-	-	-	-	-	-	-	-	-	-	-
1800	16	32	40	50	63	63	-	-	-	-	-	-	-	-	-	-	-	-	-	-
2000	20	32	40	50	63	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-
Electronic ballast
35	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6
70	6	6	6	6	6	6	6	6	6	6	6	6	10	10	10	10	10	10	10	10
150	6	6	6	6	6	6	6	10	10	10	16	16	16	16	16	16	16	20	20	20

Fig. N57: Metal halide (with PF correction) - Vac = 230 V

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Lamp power (W)	Number of lamps per circuit
	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20
MCB rating C tripping curve
1800	16	32	40	50	50	50	50	63	63	-	-	-	-	-	-	-	-	-	-	-
2000	16	32	40	50	50	50	50	63	63	-	-	-	-	-	-	-	-	-	-	-
MCB rating D tripping curve
1800	16	20	32	32	32	32	50	63	63	-	-	-	-	-	-	-	-	-	-	-
2000	16	25	32	32	32	32	50	63	-	-	-	-	-	-	-	-	-	-	-	-

Fig. N58: Metal halide (with ferromagnetic ballast and PF correction) - Vac = 400 V

Choice of circuit-breaker for LED lamps and fixtures

Use of circuit breakers

The new lighting technologies with electronic interfaces (ballasts, drivers) cause a high transient inrush current at power up that can trip the circuit breaker.

These phenomena are particularly increased with LED lighting.

Coordination curves between the number of LED luminaires and the circuit breaker rating:

Maximum number of luminaires depending on the circuit breaker rating and curve

	Circuit breaker rating	10 A				16 A				20 A
Unit power of the luminaire (W)	Curve	B	C	D	B, C, D with iCT+ or iTL+	B	C	D	B, C, D with iCT+ or iTL+	B	C	D	B, C, D with iCT+
10		15	30	48	-	22	44	69	-	32	63	98	-
30		11	24	38	57	17	34	54	90	25	49	77	110
50		8	17	27	41	12	25	39	66	18	35	56	83
75		4	11	17	28	7	15	25	44	11	21	36	55
150		-	5	9	13	2	7	12	22	4	9	18	28

Fig. N60 – Coordination between circuit breaker and luminaires LED

According to the control device used, the transient current surge may:

• require the circuit breaker to be derated according to the number of luminaires /circuit breaker rating coordination curves, when using standard control devices: CT, TL (electromechanical control device),
• be reduced by the use of the following technologies:
  • softStart: using a command integrated in the driver or a dimmer switch,
  • controlled contactor (iTL+, iCT+) (closes when the voltage passes through "0", derating is related to the Cos φ of the lighting circuit).

These technologies allow circuit breakers without derating related to the technology of the lamps to be used.

Example:

Circuit rated power = 230 V AC x Circuit breaker rating x Cos φ.