It is important when installing lighting or any form of electrics in a bathroom that a certified and competent electrician carries out the work. The work that they carry out must conform to Part P of the Building Regulations along with the 17th edition of BS 7671:2008 Amn 3 Requirements for Electrical Installations (Wiring Regulations).
There is also a rule that must be followed such as what lights can be installed in the bathroom and where they can be installed. For example if you wanted a light above your shower the light has to conform with the International Protection BS EN 60529:1992 ratings. As this light comes into direct contact with a large percentage of humidity the IP rating is IP65.
There is different if lights are going to be installed within the bath or shower try as it must be protected by a SELV source not exceeding 12V a.c r m s and the appropriate IP rating for immersion in water.
Steam and water vapour is also something that should be considered when you choose your lighting. As lights are often left on without realising it they have a tendency to overheat when combined with vapour. So many electricians combat this risk by linking the lights to a PIR switch so that the lights would only come on when someone enters the bathroom and they would switch off themselves when they cannot detect movement.
Many home owners tend to opt for a simple but effective light known as the globe light. The globe light itself tends to be installed in the centre of the bathroom ceiling so it provides adequate lighting throughout the room. These lights are pretty flexible in terms of the lamps that can be used as bayonet bulbs, ES bulbs and low energy bulbs can be used. The globe is often made from either glass or Perspex and the body of the light is screwed to the ceiling. Globe lighting comes in many shapes, sizes and colours so you are sure to find something to suit your bathroom!