Guide to the Wiring Regulations
Table C 9.3 (Continued.) Type C circuit breaker and RCBO (to BS EN 60898 or 61009) Type of circuit
Cable csa pvc/pvc (mm2)
Circuit breaker rating (A)
Maximum length for TN-C-S PME (m)
Maximum length for TN-S (m)
MCB
RCD or RCBO
MCB
RCD or RCBO
Oven (no hob)
2.5/1.5
16
46
55
27
35
-
Immersion heater
2.5/1.5
16
46
55
27
35
Shower to 30 A (7.2 kW)
6/2.5
32
49
NP
NP
A, C, 100, 102; see note 1
51
NP
NP
All
note 2 Shower to 40 A (9.6 kW)
10/4
40
Installation method
note 2 Storage radiator
2.5/1.5
16
46
51
21
35
Fixed lighting (excl. switch drops)
1.5/1.0
6
53
53
53
53
Note 1: If the cable is installed as per installation methods 101 or 103 a larger csa cable is required or thermosetting cable per 4E3A. Note 2: RCD (or RCBO) required. Note 3: NP means not permitted.
Table C 9.4 Standard domestic final circuit lengths cartridge fuses BS 1361. Cartridge fuses BS 1361 Type of circuit
Cable csa pvc/pvc (mm2)
Fuse rating (A)
Maximum length for TN-C-S PME (m)
Maximum length for TN-S (m)
MCB
RCD or RCBO
MCB
RCD or RCBO
Ring 13 A socket outlet
2.5/1.5
30
note 2
111
note 2
111
Radial 13 A socket outlets
2.5/1.5
20
40
40
40
40
Cooker (oven and hob)
6/2.5
30
53
53
28
53
Oven (no hob)
2.5/1.5
15
32
32
32
32
Immersion heater
2.5/1.5
15
32
32
32
32
Shower to 30 A (7.2 kW)
6/2.5
30
note 2
53
note 2
53
Shower to 40 A (9.6 kW)
10/4
45
note 2
66
note 2
66
Storage radiator
2.5/1.5
15
30
30
30
30
Fixed lighting (excl. switch drops)
1.5/1.0
5
53
53
53
53
Installation method
A, C, 100, 102, see note 1
All
Note 1: If the cable is installed as per installation methods 101 or 103 a larger csa cable is required or thermosetting cable per 4E3A. Note 2: RCD (or RCBO) required. Note 3: NP means not permitted.
C
78