Lighting FAQs
Expert answers to common questions about LED lighting, dimmers, light fittings, IP ratings for bathrooms, and lighting design for UK homes and commercial properties.
1
LED bulbs use up to 90% less energy than traditional incandescent bulbs and last 15,000–25,000 hours compared to 1,000 hours for incandescent. At the UK average electricity rate of ~24p/kWh, replacing 20 incandescent bulbs in a typical home with LEDs can save approximately £75–120 per year. LEDs also produce less heat, reducing cooling costs in commercial environments, and are available in a wide range of colour temperatures from warm white (2700K) to daylight (6500K).
2
Colour temperature is measured in Kelvin (K). Warm white (2700K–3000K) creates a cosy, relaxed atmosphere suitable for living rooms and bedrooms. Cool white (4000K) is crisp and clean, ideal for kitchens, bathrooms, and offices. Daylight (5000K–6500K) mimics natural light and is often used in retail, healthcare, and task lighting. For consistency, use the same colour temperature throughout a room.
3
Lumens (lm) measure the total amount of visible light emitted. Unlike watts (which measure power consumption), lumens indicate actual brightness. As a guide: 400lm replaces a 40W incandescent, 800lm replaces 60W, and 1600lm replaces 100W. For general room lighting, aim for 300–500 lux in living areas, 500 lux in kitchens, and 200 lux in bedrooms. Multiply the required lux by the room area (m²) to calculate total lumens needed.
4
Bathrooms are divided into zones under BS 7671. Zone 0 (inside the bath/shower) requires IP67. Zone 1 (above the bath/shower up to 2.25m) requires IP44 minimum, with IP65 recommended. Zone 2 (within 0.6m of Zone 1) also requires IP44. Outside these zones, standard fittings can be used but IP20 is the absolute minimum. Always install bathroom lighting using an electrician familiar with BS 7671 Part 7 special locations requirements.
5
No — you need dimmable LED bulbs and a compatible LED dimmer switch. Standard (non-dimmable) LEDs may flicker or fail when used with dimmers. Leading-edge dimmers (designed for incandescent bulbs) often cause flickering with LEDs; trailing-edge (electronic) dimmers are specifically designed for LED loads. Always check the dimmer's minimum load rating — many LED dimmers require a minimum of 10W, which can mean needing at least 3–4 LED bulbs per circuit.
6
GU10 spotlights have a twist-and-lock fitting and run directly from the mains (230V). MR16 spotlights have a bi-pin fitting and require a 12V transformer (driver). GU10 is the most common choice for new installations as there is no separate transformer to install or replace. MR16 is typically found in older halogen installations. When replacing MR16 halogens with LEDs, you may also need to replace the transformer with an LED-compatible driver.
7
Smart lighting systems allow you to control lights via smartphone apps, voice assistants (Alexa, Google Home, Apple HomeKit), or automated schedules. Systems include smart bulbs (replace standard bulbs, connect via Wi-Fi or Zigbee), smart switches (replace the wall switch, work with any bulb), and smart systems (Hue, LIFX, Casambi). Smart switches are generally recommended for retrofit installations as they work with any bulb and maintain wall control. All smart lighting installations involving mains wiring require a qualified electrician.
8
Emergency lighting provides illumination when the mains power fails, enabling safe evacuation. Under BS 5266, emergency lighting is required in all commercial premises, public buildings, HMOs, and communal areas of residential blocks. It is not required in single-family homes. Emergency luminaires must illuminate escape routes to at least 1 lux (open areas) or along the centreline of the escape route (1 lux at floor level). See our Emergency Lighting Authority Hub for full guidance.