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Fire Resisting Cables

Current Rating and Voltage Drop

Multi-Core Cables having XLPE Insulation, Armoured (Copper Conductor) 600/1000V

 

 

Current-Carrying Capacities (Amp) XLPE /SWA/PVC Cables:

Size of Conductor	Reference Method 1 (Clipped direct)		Reference Method 11 (on perforated cable tray) or Reference Method 13 (free air)		In Single Way Ducts		Laid Direct in Ground
	1 2-core cable 1-phase ac or dc	1 3- or 4-core cable 3-phase ac	1 2-core cable 1-phase ac or dc	1 3- or 4-core cable 3-phase ac	1 2-core cable 1-phase ac or dc	1 3- or 4-core cable 3-phase ac	1 2-core cable 1-phase ac or dc	1 3- or 4-core cable 3-phase ac
1 mm²	2 A	3 A	4 A	5 A	6 A	7 A	8 A	9 A
1.5	27	23	29	25	-	23	-	28
2.5	36	31	39	33	-	30	-	36
4	49	42	52	44	-	40	-	48
6	62	53	66	56	-	50	-	60
10	85	73	90	78	-	65	-	80
16	110	94	115	99	115	94	140	115
25	146	124	152	131	145	125	180	150
35	180	154	188	162	175	150	215	180
50	219	187	228	197	210	175	255	215
70	279	238	291	251	260	215	315	265
95	338	289	354	304	310	260	380	315
120	392	335	410	353	355	300	430	360
150	451	386	472	406	400	335	480	405
185	515	441	539	463	455	380	540	460
240	607	520	636	546	520	440	630	530
300	698	599	732	628	590	495	700	590
400	787	673	847	728	660	560	790	670

Note: Rating factors for ambient temperature other than 30℃ please refer Table C

Rating factors for ground temperature other than 15℃ please refer Table D

Group Rating Factor please refer to Table F & Table G

Voltage Drop (Per Amp Per Meter) XLPE/SWA/PVC Cables :

Size of Conductor	2-core cable dc	2-core cables 1-phase ac			3- & 4-core cables 3-phase ac			2-core cables 1-phase ac		3- or 4-core cables 3-phase ac
								In ducts	In ground	In ducts	In ground
1 mm²	2 mV/A/m	3 mV/A/m			4 mV/A/m			5 mV/A/m	6 mV/A/m	7 mV/A/m	8 mV/A/m
1.5	31	31			27			31	31	25	25
2.5	19	19			16			19	19	15	15
4	12	12			10			12	12	9.7	9.7
6	7.9	7.9			6.8			7.9	7.9	6.5	6.5
10	4.7	4.7			4.0			4.7	4.7	3.9	3.9
16	2.9	2.9			2.5			2.9	2.9	2.6	2.6
		r	x	z	r	x	z
25	1.85	1.85	0.16	1.9	1.6	0.14	1.65	1.9	1.9	1.6	1.6
35	1.35	1.35	0.155	1.35	1.15	0.135	1.15	1.35	1.35	1.2	1.2
50	0.98	0.99	0.155	1.00	0.86	0.135	0.87	1.00	1.00	0.87	0.87
70	0.67	0.67	0.150	0.69	0.59	0.130	0.60	0.69	0.69	0.61	0.61
95	0.49	0.50	0.150	0.52	0.43	0.130	0.45	0.52	0.52	0.45	0.45
120	0.39	0.40	0.145	0.42	0.34	0.130	0.37	0.42	0.42	0.36	0.36
150	0.31	0.32	0.145	0.35	0.28	0.125	0.30	0.35	0.35	0.30	0.30
185	0.25	0.26	0.145	0.29	0.22	0.125	0.26	0.29	0.29	0.25	0.25
240	0.195	0.20	0.140	0.24	0.175	0.125	0.21	0.24	0.24	0.21	0.21
300	0.155	0.16	0.140	0.21	0.140	0.120	0.185	0.21	0.21	0.19	0.19
400	0.120	0.13	0.140	0.19	0.115	0.120	0.165	0.19	0.19	0.18	0.18

Note: r=conductor resistance at operating temperature

Z=impedance, x=reactance

Table C: Rating Factors for Other Ambient Air Temperatures (XLPE Insulated)

Ambient Temperature	25℃	30℃	35℃	40℃	45℃	50℃	55℃	60℃	65℃	70℃	75℃	80℃	85℃
Rating Factor	1.02	1.00	0.96	0.91	0.87	0.82	0.76	0.71	0.65	0.58	0.50	0.41	0.29

Table D: Rating Factors for Other Ground Temperatures (XLPE Insulated)

Ground Temperature	15℃	20℃	25℃	30℃	35℃	40℃	45℃	50℃
Rating Factor	1.00	0.97	0.93	0.89	0.86	0.82	0.77	0.73

Table F: Group Rating Factors for Cables Installation

Group Rating Factors			Number of Circuits
			2	3	4	5	6	7	8	9	10	11	12
1	For circuits of 2 Single core cables laid flat touching horizontal formation, laid direct in ground		0.79	0.68	0.62	0.57	0.54	0.52	0.50	0.48	0.47	0.46	0.45
2	For circuits of 3 Single core cables in trefoil touching, laid direct in ground		0.78	0.66	0.61	0.56	0.53	0.50	0.49	0.47	0.46	0.44	0.43
			Number of Cables in a Group
			2	3	4	5	6	7	8	9	10	11	12
3	For twin or multi-cores cables in horizontal formation, laid direct in ground	Spaced 0.15m	0.87	0.78	0.74	0.70	0.68	0.66	0.64	0.63	0.62	0.61	0.60
		Spaced 0.30m	0.91	0.84	0.81	0.78	0.77	0.75	0.75	0.74	0.73	0.73	0.72
			Number of Ducts in a Group
			2	3	4	5	6	7	8	9	10	11	12
4	For twin or multi-cores cables in single-way ducts horizontal formation spaced 0.30m apart		0.93	0.88	0.85	0.83	0.82	0.81	0.80	0.79	0.79	0.78	0.78

Table G Correction Factors for Groups of More than One Circuit of Single Core Cables, or More than One Multi-Cores Cable

Reference Methods of Installation		Correction Factor (Cg)
		Number of Circuits or Multi-cores Cables
		2	3	4	5	6	7	8	9	10	12	14	16	18	20
Enclosed (Method 3 or 4) or bunched and clipped direct to a non-metallic surface (Method 1)		0.80	0.70	0.65	0.60	0.57	0.54	0.52	0.50	0.48	0.45	0.43	0.41	0.39	0.38
Single layer clipped to a non-metallic surface (Method 1)	Touching	0.85	0.79	0.75	0.73	0.72	0.72	0.71	0.70	-	-	-	-	-	-
	Spaced*	0.94	0.90	0.90	0.90	0.90	0.90	0.90	0.90	0.90	0.90	0.90	0.90	0.90	0.90
Single layer multi-cores on a perforated metal cable tray, vertical or horizontal(Method 11)	Touching	0.86	0.81	0.77	0.75	0.74	0.73	0.73	0.72	0.71	0.70	-	-	-	-
	Spaced*	0.91	0.89	0.88	0.87	0.87	-	-	-	-	-	-	-	-	-
Single layer single core on a perforated metal cable tray, touching (Method 11)	Horizontal	0.90	0.85	-	-	-	-	-	-	-	-	-	-	-	-
	Vertical	0.85	-	-	-	-	-	-	-	-	-	-	-	-	-
Single layer multi-cores touching on ladder supports (Method 13)		0.86	0.82	0.80	0.79	0.78	0.78	0.78	0.77	-	-	-	-	-	-

*Space means a clearance between adjacent surfaces of at least one cable diameter (De). Where the horizontal clearance between adjacent cables exceeds 2 De, no correction factor need be applied.

Note:

The factors in the table are applicable to group of cables all of one size. The value of current derived from application of the appropriate factors is the maximum continuous current to be carried by any of the cables in the group.

If, due to known operating conditions, a cable is expected to carry not more than 30% of it’s grouped rating, it may be ignored for the purpose of obtaining the rating factor for the rest of the group.
For example, a group of N loaded cables would normally require a group reduction factor of Cg applied to the tabulated It. However, if M cables in the group carry loads which are not greater than 0.3CgIt amperes, the other cables can be sized by using the group rating factor corresponding to (N-M) cables.

Factors are given for single layer of cables do not apply when cables are installed in more than one layer touching each other.

For circuits having more than one cable in parallel per phase, each set of three conductors should be considered as a circuit for the purpose of this table.