Cable Current Ratings

Current carrying capacity (Iz) for common cable types by installation method

BS 7671:2018+A2:2022 Tables 4D1A-4J1

Twin Singles SWA SWA Mineral Flexible H07RN-F

Important: These are tabulated values (It)

Apply correction factors for ambient temperature (Ca), grouping (Cg), and thermal insulation (Ci) as required. The installed current rating is: Iz = It × Ca × Cg × Ci

Twin & Earth (6242Y)

Flat twin and earth cable with PVC insulation

Reference: Table 4D5 | Max temp: 70°C

Size (mm²)	Clipped Direct	Conduit in Wall	Conduit in Ceiling	In Trunking	On Cable Tray
1	15.5	13.5	13	13.5	15.5
1.5	20	17.5	16.5	17.5	20
2.5	27	24	23	24	27
4	37	32	30	32	37
6	47	41	38	41	47
10	64	57	52	57	64
16	85	76	69	76	85

Singles in Conduit/Trunking

Single core PVC cables (6491X) in conduit or trunking

Reference: Table 4D1A | Max temp: 70°C

Size (mm²)	Clipped Direct	Conduit in Wall	Conduit in Ceiling	In Trunking	On Cable Tray	Free Air
1	15.5	13.5	13	13.5	16.5	19
1.5	20	17.5	16.5	17.5	22	24
2.5	27	24	23	24	30	33
4	37	32	30	32	40	45
6	47	41	38	41	51	58
10	65	57	52	57	70	80
16	87	76	69	76	94	107
25	114	101	90	101	119	138
35	141	125	111	125	148	171
50	182	151	133	151	180	209
70	234	192	168	192	232	269
95	284	232	201	232	282	328
120	330	269	232	269	328	382

SWA PVC (BS 5467)

Steel wire armoured cable with PVC insulation

Reference: Table 4D4A | Max temp: 70°C

Size (mm²)	Clipped Direct	Buried Direct	On Cable Tray	Free Air
1.5	21	27	21	26
2.5	28	36	28	35
4	37	46	37	45
6	47	57	47	57
10	64	76	64	78
16	84	98	84	102
25	110	125	110	133
35	134	151	134	163
50	161	179	161	196
70	200	219	200	243
95	241	262	241	293
120	278	299	278	338
150	313	335	313	380
185	354	377	354	430
240	410	434	410	498
300	463	488	463	563

SWA XLPE (BS 5467)

Steel wire armoured cable with XLPE insulation

Reference: Table 4E4A | Max temp: 90°C

Size (mm²)	Clipped Direct	Buried Direct	On Cable Tray	Free Air
1.5	25	32	25	31
2.5	34	42	34	42
4	44	53	44	55
6	57	67	57	70
10	77	89	77	95
16	102	116	102	125
25	133	148	133	163
35	163	178	163	200
50	196	211	196	240
70	244	258	244	299
95	296	307	296	363
120	343	351	343	420
150	387	393	387	474
185	440	442	440	540
240	514	509	514	631
300	583	572	583	716

Mineral Insulated (MICC)

Mineral insulated copper clad cable

Reference: Table 4J1 | Max temp: 105°C

Size (mm²)	Clipped Direct	Conduit in Wall	Free Air
1	23	18	27
1.5	28	23	33
2.5	38	31	44
4	50	40	57
6	62	51	71
10	82	68	94
16	106	89	121
25	135	115	155

Flexible Cable (H05VV-F)

PVC flexible cord for appliance connections

Reference: Table 4D3A | Max temp: 70°C

Size (mm²)	Clipped Direct	Free Air
0.5	3	3
0.75	6	6
1	10	10
1.5	13	16
2.5	18	25
4	23	32

H07RN-F (Heavy Rubber Flex)

Heavy duty rubber flexible cable

Reference: Table 4D3A | Max temp: 60°C

Size (mm²)	Clipped Direct	Free Air
1	14	17
1.5	18	22
2.5	25	30
4	33	40
6	43	52
10	60	72
16	80	96
25	106	127
35	131	157
50	159	190
70	202	242
95	245	294
120	284	340

Notes

• Values are for copper conductors. Aluminium has lower ratings.
• Reference ambient temperature is 30°C (25°C for buried cables).
• Single-phase values shown. Three-phase may differ slightly.
• Always verify against the full BS 7671 tables for critical applications.

Installation Method Key

Clipped Direct - Clipped direct to surface or on tray (Reference Method C)

Conduit in Wall - Enclosed in conduit on a wall (Reference Method B)

Conduit in Ceiling - Enclosed in conduit in thermally insulated ceiling

In Trunking - Enclosed in trunking

On Cable Tray - On perforated cable tray (Reference Method E/F)

Buried Direct - Buried direct in ground

Free Air - In free air with spacing

Size (mm²)	Clipped Direct	Buried Direct	On Cable Tray	Free Air
1.5	21	27	21	26
2.5	28	36	28	35
4	37	46	37	45
6	47	57	47	57
10	64	76	64	78
16	84	98	84	102
25	110	125	110	133
35	134	151	134	163
50	161	179	161	196
70	200	219	200	243
95	241	262	241	293
120	278	299	278	338
150	313	335	313	380
185	354	377	354	430
240	410	434	410	498
300	463	488	463	563

Size (mm²)	Clipped Direct	Buried Direct	On Cable Tray	Free Air
1.5	25	32	25	31
2.5	34	42	34	42
4	44	53	44	55
6	57	67	57	70
10	77	89	77	95
16	102	116	102	125
25	133	148	133	163
35	163	178	163	200
50	196	211	196	240
70	244	258	244	299
95	296	307	296	363
120	343	351	343	420
150	387	393	387	474
185	440	442	440	540
240	514	509	514	631
300	583	572	583	716

Size (mm²)	Clipped Direct	Conduit in Wall	Free Air
1	23	18	27
1.5	28	23	33
2.5	38	31	44
4	50	40	57
6	62	51	71
10	82	68	94
16	106	89	121
25	135	115	155

Size (mm²)	Clipped Direct	Free Air
1	14	17
1.5	18	22
2.5	25	30
4	33	40
6	43	52
10	60	72
16	80	96
25	106	127
35	131	157
50	159	190
70	202	242
95	245	294
120	284	340

Size (mm²)	Clipped Direct	Buried Direct	On Cable Tray	Free Air
1.5	21	27	21	26
2.5	28	36	28	35
4	37	46	37	45
6	47	57	47	57
10	64	76	64	78
16	84	98	84	102
25	110	125	110	133
35	134	151	134	163
50	161	179	161	196
70	200	219	200	243
95	241	262	241	293
120	278	299	278	338
150	313	335	313	380
185	354	377	354	430
240	410	434	410	498
300	463	488	463	563

Size (mm²)	Clipped Direct	Buried Direct	On Cable Tray	Free Air
1.5	25	32	25	31
2.5	34	42	34	42
4	44	53	44	55
6	57	67	57	70
10	77	89	77	95
16	102	116	102	125
25	133	148	133	163
35	163	178	163	200
50	196	211	196	240
70	244	258	244	299
95	296	307	296	363
120	343	351	343	420
150	387	393	387	474
185	440	442	440	540
240	514	509	514	631
300	583	572	583	716

Size (mm²)	Clipped Direct	Conduit in Wall	Free Air
1	23	18	27
1.5	28	23	33
2.5	38	31	44
4	50	40	57
6	62	51	71
10	82	68	94
16	106	89	121
25	135	115	155

Size (mm²)	Clipped Direct	Free Air
1	14	17
1.5	18	22
2.5	25	30
4	33	40
6	43	52
10	60	72
16	80	96
25	106	127
35	131	157
50	159	190
70	202	242
95	245	294
120	284	340

Size (mm²)	Clipped Direct	Buried Direct	On Cable Tray	Free Air
1.5	21	27	21	26
2.5	28	36	28	35
4	37	46	37	45
6	47	57	47	57
10	64	76	64	78
16	84	98	84	102
25	110	125	110	133
35	134	151	134	163
50	161	179	161	196
70	200	219	200	243
95	241	262	241	293
120	278	299	278	338
150	313	335	313	380
185	354	377	354	430
240	410	434	410	498
300	463	488	463	563

Size (mm²)	Clipped Direct	Buried Direct	On Cable Tray	Free Air
1.5	25	32	25	31
2.5	34	42	34	42
4	44	53	44	55
6	57	67	57	70
10	77	89	77	95
16	102	116	102	125
25	133	148	133	163
35	163	178	163	200
50	196	211	196	240
70	244	258	244	299
95	296	307	296	363
120	343	351	343	420
150	387	393	387	474
185	440	442	440	540
240	514	509	514	631
300	583	572	583	716

Size (mm²)	Clipped Direct	Conduit in Wall	Free Air
1	23	18	27
1.5	28	23	33
2.5	38	31	44
4	50	40	57
6	62	51	71
10	82	68	94
16	106	89	121
25	135	115	155

Size (mm²)	Clipped Direct	Free Air
1	14	17
1.5	18	22
2.5	25	30
4	33	40
6	43	52
10	60	72
16	80	96
25	106	127
35	131	157
50	159	190
70	202	242
95	245	294
120	284	340