Lighting installation

The most common mistake is treating a ceiling as a grid and spacing lights evenly across it. You end up with a bright ceiling and shadows exactly where you need light.

• Light the work, not the room: over the front edge of a worktop, not over the middle of the floor.
• Layer it. General light, task light and something low and warm for the evening, on separate switching.
• Warmer colour temperatures (2700–3000K) for living spaces; cooler only where you genuinely need contrast.
• Fewer, better fittings beat more cheap ones, and mean fewer holes in the ceiling.
• Think about where the switches go before first fix. Coming into a room and reaching for a switch that isn't there is a twenty-year irritation.

Downlights cut holes in a ceiling, and in a house that ceiling is often doing a fire-separation job and holding loft insulation above it. Fittings need to be chosen for that, not just for looks.

• Fire-rated fittings where the ceiling separates storeys, so the hole doesn't defeat the ceiling's fire resistance.
• Fittings rated to be covered by insulation, or proper stand-offs, so loft insulation doesn't have to be pulled away from them.
• Enough clearance above the ceiling for the fitting and its driver, worth checking before the holes are cut.

If you're replacing old mains-voltage halogen downlights, that's a straightforward and worthwhile swap: far less heat in the ceiling void, and a fraction of the running cost.

Most LED dimming complaints (buzzing, flicker, lamps that won't go low, one lamp glowing when it's off) come from a mismatch between the dimmer and the lamps rather than a fault.

LED loads are small and behave differently to old filament lamps, so the dimmer needs to be an LED-rated one with a suitable minimum load, and the lamps need to actually be dimmable. Getting the pairing right is the whole job.

Bathrooms are divided into zones by distance from the bath or shower, and each zone sets a minimum IP rating for anything installed in it. It isn't a formality. It's the difference between a fitting that survives and one that fills with water.

Illuminated mirrors, shaver sockets and extractor fans all need siting with the zones in mind, and the extractor needs to actually vent somewhere rather than into the loft.