There are two basic types of socket-outlet intended to supply an electric shaver:
- The type with a transformer, and
- The type without.
With certain exceptions only the type with a transformer may be installed in a location containing a bath or shower. Information on both types is given in this article.
Considerations applying to both types
Whether with a transformer or without, shaver socket-outlets complying with the relevant British Standards accept only 2-pin reversible plugs of the kind normally fitted to an electric shaver, and are shuttered.
Both types of shaver socket-outlet may be either Class I construction (having metal parts required to be earthed) or Class II construction (having no exposed metal parts required to be earthed). However, in all cases, a circuit protective conductor has to be run to and terminated at the shaver socket-outlet, just as is required for any other point or accessory (Regulation 411.3.1.1 refers).
The type with a transformer
A shaver socket-outlet with a transformer is called a shaver supply unit. The term ‘shaver supply unit’ means: an accessory embodying a shaver transformer and one or more socket-outlets.
A shaver supply unit complying with BS EN 61558-2-5 may be installed in zone 2 of a location containing a bath or shower (Regulation 701.512.3 refers).
Neither the rated supply voltage nor rated output voltage of a shaver supply may exceed 250 V a.c. The no-load output voltage is not to exceed 275 V and the difference between the no-load output voltage and the output voltage under load shall not exceed 20 % of the load output voltage. For example, a no-load voltage of 275 V and an output load voltage of 230 V would lead to percentage variance approaching 20 %. The output voltamperes must be not less than 20 VA and not more than 50 VA.
Where more than one rated output voltage is provided, the different voltages may be available from separate socket-outlets of the shaver supply unit. Alternatively, a changeover switch may be provided to switch between the voltages. The selected output voltage setting has to be clearly discernible.
The transformer of a shaver supply unit is an isolating transformer, intended to provide protection against electric shock by ‘electrical separation’. The transformer is of the short-circuit proof type (either inherently or noninherently).
A thermal cut-out is provided in a shaver supply unit to limit the temperature of the transformer under conditions of short-circuit or overload. The cut-out may be of either the self-resetting type or the manually resetting type.
The front of a shaver supply unit is marked with the rated voltage(s) and with the symbol shown left. A degree of protection of at least IPX1 is provided by a shaver supply unit.
The type without a transformer
A shaver socket-outlet without a transformer should conform to BS 4573 (Regulation 553.1.5(ii) refers).
A shaver socket-outlet conforming to BS 4573 has a restricted continuous current rating of 200 mA for use on voltages of 200 V to 250 V a.c. only. The shaver socket-outlet incorporates a current limiting device, other than a fuse, which may be of either the manually-resetting or the self-resetting type. The current limiting device operates within one hour at a current of 300 mA, and within one minute at a current of 500 mA. The socket-outlet may also incorporate a fuse complying with BS 646 and having a current rating not exceeding 1 A, to protect the current-limiting device against fault current.
The front of a shaver socket-outlet conforming to BS 4573 is marked ‘Shavers only 200-250 V a.c.’ and the back is marked `NOT for use in a bathroom’. This is reinforced by Regulation 553.1.5(ii), which does not allow a shaver socket-outlet conforming to BS 4573 to be installed in a bathroom.
A socket-outlet without a transformer is prohibited within 3 m horizontally from the boundary of zone 1 of a location containing a bath or shower (Regulation 701.512.3 refers).
For more information please visit www.elecsa.co.uk
