Bell wire, in general, is unsuitable for use in fixed installations or for connecting portable appliances.The term ‘bell wire’ is taken to mean two-core 0.5mm/1.036 unsheathed cable commonly-used for wiring the ELV door bell circuit of a house where an electric bell is employed. Bell wire, often used for bell circuits or for wiring loudspeakers, is in most cases, only suitable for extra-low voltage (50 V or less).
Snags commonly-encountered center on the use of bell wire for 230 V applications such as:
- Connecting items of current-using equipment (often those having only a low consumption such as clocks and clock points)
- Connecting between a ceiling rose and a lamp holder
- DIY-type work (for example, a luminaire installed in a loft)
- The wiring of 230 V appliances (for example, standard lamps, table lamps or electrical tools).
SOLUTION
The bell wire must be replaced. A suitable replacement cable would be a pvc insulated and sheathed non-armoured cable to BS 6004. The minimum cross-sectional area of the copper conductors in a.c. power and lighting circuits must be 1mm2 (Regulations 524-01-01 and 524-02-01).
Where an appliance wired in bell flex is encountered, the reasons for the risk of danger should be explained to the user who should be encouraged to have repairs made (the cable replaced) as soon as possible.
Regulation 524-01-01 (part of)
The nominal cross-sectional area of phase conductors in a.c. circuits and of live conductors in d.c. circuits shall not be less than the values specified in table 52C.
| Type of wiring system | Use of circuit | Conductor | |
|---|---|---|---|
| Material | Minimum permissible nominal cross-sectional area (mm2) | ||
| Cables and insulated conductors | Power and lighting circuits | Copper Aluminium |
1.0 |
| Signalling and control circuits | Copper | 0.5 (see Note 2) | |
| Flexible connections with insulated conductors and cables | For a specific appliance | Copper | As specified in the relevant British Standard |
| For any other application | 0.5 (see Note 2) | ||
| Extra-low Voltage circuits for special applications | 0.5 | ||
Notes
(1) Connectors used to terminate aluminium conductors shall be tested and approved for this specific use.
(2) For cables containing 7 or more cores in signalling and control circuits intended for electronic equipment, a minimum nominal cross-sectional area of 0.1mm2 is permitted.
Regulation 524-02-01
In a single-phase circuit the neutral conductor shall have a cross-sectional area not less than the phase conductor.