Great care needs to be taken
when choosing bathroom lighting as the regulations are strict concerning the
type of light you can use.

The bathroom mirror deserves some special attention and a diffused glass light
either side will give good general illuminations where it is needed. The
alternative is a halogen downlight from the ceiling or fluorescent strip light
over the mirror.
For general illumination in the rest of the bathroom either use downlights for
their refreshing halogen colour or a high output flush ceiling fitting to suit
the décor.
Portable lights are not permitted in a bathroom so for mood lighting use ceiling
mounted directional spotlights aimed away from the bath and at interesting
features.
Lights designed specifically for showers are available and must be carefully
fitted according to their instructions.
The following information
is a guide to help you understand what fittings can be placed where. This is not
an installation guide and reference should be made to the IEE Wirings
Regulations (16th Edition) or a qualified electrician.
Firstly it is important to understand the rating by which bathroom and some
outdoor lights are classified. IP rating stands for ‘Ingress Protection’ and is
always followed by two characters. The first character specifies the degree of
protection against particles or solid objects. Starting with 0 for no protection
it runs up to a maximum or 6 which is total protection against ingress of dust.
Of more interest here is the second digit that states the degree of protection
from ingress of moisture. This ranges from 0 for no protection to 8 for a light
which may be totally submerged in water up to a specified depth.
The ratings that interest us are IPx4 (x is used in this case because there is
no requirement in the regulations for a level of dust protection). Lights sold
as IPx4 will have been tested for protection against water splashing from any
direction.
The diagrams below show a bathroom split into four clear zones. In zones 1, 2
and 3, if there is likelihood of a water jet being used for cleaning purposes a
minimum of IPx5 is required.

Zone 0 is inside
the bath or shower itself and any fittings used here must be low voltage (max
12v) and be rated IPx7 which is total protection when immersed in water.
Zone 1 is above the bath to a height of 2.25m. A minimum rating of IPx4 is
required here.
Zone 2 is an area stretching to 0.6m outside the bath and above the bath if
over 2.25m. An IP rating of at least IPx4 is required here.
Zone 3 is anywhere outside zones 0, 1 and 2 (subject to specific limits) and
where no water jet is likely to be used there is no IP rating required.
The IEE Regulations do not make specific reference to wash basins but in the
opinion of The Lighting Association they should be treated as Zone 2 (i.e. IPx4)
The
information here is intended as a guide and contains several generalisations for
illustrative purposes. For more technical information refer to an electrician
and specific product data.