Security Power Supplies - KT Assemblies Ltd - Technical and useful information

Conductor cross sectional area	Installation methods A to C† of table 9A ('enclosed')				Installation methods E to H of table 9A ('Clipped direct')				Installation method K of table 9A ('Defined conditions')
Conductor cross sectional area	One twin cable. With or without protective conductor single phase a/c. Or d/c.		One three-core cable, with or without protective conductor, or one four core cable phase one		One twin cable. With or without protective conductor single phase a.c. Or d.c.		One three-core cable, with or without protective conductor, or one four core cable phase one		One twin cable. With or without protective conductor single phase a.c. or d.c.		One three-core cable, with or without protective conductor, or one four core cable phase one
	Current carrying capacity	Volt drop per amp per metre	Current carrying capacity	Volt drop per amp per metre	Current carrying capacity	Volt drop per amp per metre	Current carrying capacity	Volt drop per amp per metre	Current carrying capacity	Volt drop per amp per metre	Current carrying capacity	Volt drop per amp per metre
1	2	3	4	5	6	7	8	9	10	11	12	13
mm²	A	mV	A	mV	A	mV	A	mV	A	mV	A	mV
1.0	14	42	12	37	16	42	13	37
1.5	18	28	16	24	20	28	17	24
2.5	24	17	21	15	28	17	24	15

4	32	11	29	9.2	36	11	32	9.2
6	40	7.1	36	6.2	46	7.1	40	6.2
10	53	4.2	49	3.7	64	4.2	53	3.7
16	70	2.7	62	2.3	85	2.7	70	2.3

25	79	1.8	70	1.6	108	1.8	90	1.6	114	1.8	95	1.6
35	98	1.3	86	1.1	132	1.3	115	1.1	139	1.3	122	1.1
50					163	0.92	140	0.81	172	0.92	148	0.81
						Ac / Dc				Ac / Dc
70					207	0.65/0.64	176	0.57	218	0.65/0.64	186	0.57
95					251	0.48/0.46	215	0.42	265	0.48/0.46	227	0.42

120					290	0.40/0.36	251	0.34	306	0.40/0.36	265	0.34
150					330	0.32/0.25	287	0.29	348	0.32/0.25	302	0.29
185					380	0.29/0.23	330	0.24	400	0.29/0.23	348	0.24
240					450	0.25/0.18	392	0.20	474	0.25/0.18	413	0.20
300					520	0.23/0.14	450	0.18	548	0.23/0.14	474	0.18
400					600	0.22/0.11	520	0.17	632	0.22/0.11	548	0.17

† For installation Method C, the tabulated values are applicable only to the range up to and including 35mm². For larger sizes in this installation method, see ERA report 69-30. For cables in ducts in the floor of a building, the ERA ratings must be adjusted by the appropriate factor for the ambient temperature.

The current carrying capacities in columns 6 and 8 are applicable to flexible cables to BS 6004 Table 1(b) where the cables are used in fixed installations.

Correction Factors

For Ambient Temperature

Ambient temperature	25°C	35°C	40°C	45°C	50°C	55°C	60°C	65°C
Correction factor	1.06	0.94	0.87	0.79	0.71	0.61	0.50	0.35

Sample Formulas for the Volt Drop Table

FORMULA = LENGTH X VOLT DROP X AMPS = VOLT DROP OVER LENGTH
1.0 mm TWIN CABLE FORMULA = 42 MV PER AMP PER METER
10 metres at 5 amp with 1.0mm twin =	10 x 5 x 42 =	2100 mv 1000	2.1 volts
20 metres at 5 amp with 1.0mm twin =	20 x 5 x 42 =	4200 MV 1000	4.2 volts
30 metres at 5 amp with 1.0mm twin =	30 x 5 x 42 =	6300 MV 1000	6.3 volts
50 metres at 5 amp with 1.0mm twin =	50 x 5 x 42 =	10500 MV 1000	10.5 volts
75 metres at 5 amp with 1.0mm twin =	75 x 5 x 42 =	15750 MV 1000	15.7 volts
100 metres at 5 amp with 1.0mm twin =	100 x 5 x 42 =	21000 MV 1000	21 volts

1.5 mm TWIN CABLE FORMULA = 28 MV PER AMP PER METER
10 metres at 5 amp with 1.5mm twin =	10 x 5 x 28 =	1400 MV 1000	1.4 volts
20 metres at 5 amp with 1.5mm twin =	20 x 5 x 28 =	2800 MV 1000	2.8 volts
30 metres at 5 amp with 1.5mm twin =	30 x 5 x 28 =	4200 MV 1000	4.2 volts
50 metres at 5 amp with 1.5mm twin =	50 x 5 x 28 =	7000 MV 1000	7.0 volts
75 metres at 5 amp with 1.5mm twin =	75 x 5 x 28 =	10500 MV 1000	10.5 volts
100 metres at 5 amp with 1.5mm twin =	100 x 5 x 28 =	14000 MV 1000	14.0 volts

2.5 mm TWIN CABLE FORMULA + 18mv PER AMP PER METER
10 metres at 5 amp with 2.5mm twin =	10 x 5 x 17 =	850 MV 1000	0.85 volts
20 metres at 5 amp with 2.5mm twin =	20 x 5 x 17 =	1700 MV 1000	1.7 volts
30 metres at 5 amp with 2.5mm twin =	30 x 5 x 17 =	2500 MV 1000	2.5 volts
50 metres at 5 amp with 2.5mm twin =	50 x 5 x 17 =	4250 MV 1000	4.2 volts
75 metres at 5 amp with 2.5mm twin =	75 x 5 x 17 =	6375 MV 1000	6.3 volts
100 metres at 5 amp with 2.5mm twin =	100 x 5 x 17 =	8500 MV 1000	8.5 volts


Security Power Supplies	© KT Assemblies Ltd 2003 - 2008	Web Designers: Effective Webs

Terms & Conditions