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GU10 LED Bulbs: The Complete Buying Guide for Electricians and Homeowners
The GU10 fitting is the most widely installed recessed lighting socket in UK homes. Whether retrofitting from halogen or specifying for a new build, getting lumens, colour temperature, beam angle, and dimmer compatibility right prevents call-backs. This guide covers the key decisions.
GU10 vs MR16
GU10 = mains 230V, bayonet bi-pin, 10mm pin spacing. MR16 = 12V, push-in, 5.3mm spacing, needs transformer. Not interchangeable. Measure pin spacing before ordering.
Lumens: How Bright?
| Old halogen | Lumens needed | LED wattage |
|---|---|---|
| 35W | 300–350 lm | 4–5W |
| 50W | 450–500 lm | 6–8W |
| 75W | 700–750 lm | 10–12W |
Room guide: Bedrooms/hallways 300–400 lm. Living rooms 300–450 lm ambient. Kitchens 450–500 lm minimum. Bathrooms 400–500 lm. Retail/commercial 500–700 lm.
Colour Temperature
| Kelvin | Appearance | Use |
|---|---|---|
| 2700K Warm White | Amber, halogen-match | Living rooms, bedrooms |
| 3000K | Slightly crisper | Kitchens, bathrooms, retail |
| 4000K Cool White | Neutral, clinical | Offices, workshops, garages |
| 5000–6500K Daylight | Blue-white | Specialist tasks |
Default to 2700K for domestic work. Use the same brand and Kelvin across a circuit — colour variation is visible side-by-side.
Beam Angle
- 25–36° Spot: Accent and display. Not suitable as sole room downlight.
- 38–45° Standard flood: Default for domestic downlights at 2.4m ceiling with standard spacing.
- 60°+ Wide flood: Wide spacing, low ceilings, or soft distribution rooms.
Dimmable GU10s
Always specify dimmable GU10s on a dimmer circuit. Non-dimmable LEDs behind a dimmer flicker and fail early. Check dimmer minimum load — a 10W minimum dimmer running a single 5W GU10 will behave erratically. Use a 0W minimum load dimmer, or run 3–4 GU10s minimum on the circuit.
Fire-Rated Downlights (Part B)
Building Regulations Part B requires fire-rated downlight fittings wherever the ceiling is a fire-separating element: between floors in a house, between flats, or garage-to-living-space. The fitting must maintain the 30 or 60-minute ceiling fire rating via an intumescent seal.
We stock the Integral Evofire fire-rated downlight (70–100mm cutout, IP65, from £5.49) and the Integral Brush Mini and Chrome Mini fire-rated fittings — all accept standard GU10 lamps. Browse the full fire-rated downlights collection.
IP Ratings for Bathrooms (BS 7671)
- Zone 1 (above bath/shower to 2.25m): IP45 minimum
- Zone 2 (60cm from bath edge): IP44 minimum
- Outside zones in bathroom: IP20 acceptable for ceiling fittings
The Evofire (IP65) exceeds Zone 1 requirements. The GU10 lamp should be IP65 rated or the fitting must be enclosed with its own lens in wet zones.
CRI: Colour Rendering Index
CRI measures colour accuracy vs daylight. CRI 80+ for general areas and corridors. CRI 90+ for living rooms, kitchens, and anywhere colour accuracy matters. CRI 97+ for high-end residential, retail, or art gallery work.
Buy GU10 LEDs at APM Electricals, Acton
We stock dimmable and non-dimmable GU10 LED lamps, fire-rated downlight fittings (IP65, brushed chrome, chrome), and GU10 spotlight bar fittings for same-day collection. Browse our fire-rated downlights and ceiling light fittings online.
24 Western Avenue, Acton, London W3 7TZ | 020 8702 8080 | apmi.uk. Trade accounts welcome.
Quick Reference
- 50W halogen → 5–6W LED, 450–500 lm
- Domestic ambient → 2700K warm white, 38–45° beam
- Dimmer circuit → always specify dimmable GU10
- Inter-floor ceilings → fire-rated fitting required (Part B)
- Bathroom Zone 1/2 → IP44/45+ fitting
- GU10 = 230V, 10mm pin spacing (not MR16/GU5.3)
- CRI 90+ recommended for living areas
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