Lighting, inside and out

Good lighting starts with what the room is for. A kitchen needs light on the worktops, not just in the middle of the ceiling. A living room usually wants something softer, and a way to turn it down. A landing needs switching from both ends.

We look at where the light needs to fall, where you come into the room and where the switches make sense. Two-way switching on stairs and in long rooms means nobody walks the length of a dark room to find the switch.

Older lighting circuits sometimes have no earth conductor, which rules out metal fittings. If yours is one of them, you will know before anything is bought.

Downlights give even, general light from a flush ceiling, and LED versions run cool. Three things matter when they go in:

• Fire rating. Cutting holes in a ceiling weakens it as a fire barrier. Fire-rated downlights restore it, which matters in ceilings between floors.
• Insulation. Under a loft, the fitting has to be rated to have insulation laid over it, or be kept clear of it.
• Layout. Spacing is worked out from the ceiling height and the beam angle, so the light is even rather than patchy.

Pendants hang from a ceiling rose or fitting plate. Heavy ones are fixed to a joist rather than the plasterboard, and the flex has to be rated for the weight.

Under-cabinet lights are usually LED strips or slim fittings run from a driver, a small power supply that turns mains voltage into the low voltage the LEDs use. The driver has to be sized for what it feeds and fitted where it can be reached and replaced, usually inside a cabinet.

A driver that is too small, runs too hot or is the wrong type is a common reason for LED strips flickering or failing early.

Older dimmers were made for filament bulbs. Most LED lamps need a dimmer designed for LEDs, often a trailing-edge type, with a minimum load low enough for the few watts they draw. A mismatch shows up as flicker, buzzing, lights that will not dim down, or lights that glow faintly when switched off.

Smart switches often need a neutral conductor at the switch, and many older houses do not have one there. It can be solved, but it is worth checking before you buy.

A bathroom is divided into zones around the bath or shower, and every fitting in a zone needs the right IP rating, the code for how well it keeps out dust and water.

• Zone 0 is inside the bath or shower tray. Only extra-low-voltage equipment made for it, rated IPX7, goes here.
• Zone 1 is the space directly above the bath or shower, up to 2.25 m from the floor. Fittings need at least IPX4.
• Zone 2 reaches 0.6 m beyond zone 1. Fittings need at least IPX4 here too.

Every circuit in a bathroom needs 30 mA RCD protection, and work in the zones is notifiable under Part P. Steam travels, so a rated fitting is often the sensible choice outside the zones as well.

Outside, lighting does two jobs: making the garden usable after dark, and showing you who is at the door or on the drive.

• Garden lighting: post lights along paths, uplighters in borders and under trees, wall lights over the patio, and a light in the shed or summerhouse. Low lights pointed down or into planting usually look better than flooding the whole garden.
• Security lighting with a PIR detector comes on when it senses movement and goes off after a set time, and a dusk sensor stops it working in daylight. The detector and the fitting are aimed to cover your path and drive, not the road or the neighbours’ windows.

LED floodlights are bright. A lower-output fitting aimed down often does the job better and does not dazzle anyone.

Everything outside is wet some of the time. Fittings need an IP rating for the weather, outdoor sockets go in weatherproof enclosures, and every socket outdoors needs 30 mA RCD protection.

Cable buried in the garden is steel wire armoured (SWA) or otherwise protected, laid deep enough to stay clear of a spade, with warning tape above it so the next person digging finds the tape before the cable. Cable on walls and fences is protected or fixed where it will not be damaged.

The best time to run cable to the bottom of the garden is before the patio, the paths or the new lawn go down.

Lighting work is tested and certified. Adding lights to an existing circuit gets a Minor Electrical Installation Works Certificate. A new circuit, indoors or out, gets an Electrical Installation Certificate.

New circuits and work in a bathroom’s zones are notifiable under Part P. A registered installer self-certifies the work and notifies building control, and you receive a Building Regulations compliance certificate. Changing a light fitting outside the zones is not notifiable, but it is still tested.