Replace halogen GU10 and MR16 spots with LED

1. Identify the spot

• GU10: two short pins with feet, push and twist. Mains voltage: 230 V in the UK, 120 V in the US. No transformer.
• MR16 (GU5.3): two thin straight pins, push in. 12 V, fed by a transformer in the ceiling void.

2. Match the light

Halogen	LED target	Example
35 W GU10	≥ 230 lm	3–4 W LED
50 W GU10	≥ 350 lm	Philips CorePro 4 W, 350 lm (UK); Philips 6 W, 400 lm (US)
50 W MR16	≥ 350 lm	Philips 4 W, 380 lm (US)

Halogen equivalents per UK/EU Regulation 1194/2012 (directional lamps); LED figures from the listings below. Keep the beam angle (usually 36°–40°). Choose 2700–3000K to match halogen's warm light.

3. MR16: the transformer trap

Old electronic transformers often need a minimum load of 20–35 W. A single 4 W LED is below it: flicker or nothing. Fixes: an LED driver rated for the total LED wattage, or replace the MR16 fittings with GU10 mains fittings (in the UK, that is electrical work under BS 7671; in a bathroom zone it is notifiable under Part P in England and Wales).

4. Dimmers

See our dimmable LED guide: use dimmable LEDs and an LED-rated (trailing-edge or CL) dimmer.

5. Safety and fire

Turn off the circuit at the consumer unit (UK) or breaker (US) and let halogens cool: they run at well over 100 °C. In the UK, many ceiling spots are fire-rated downlights that maintain the ceiling's fire resistance: keep them. In the US, recessed cans in contact with insulation must be IC-rated.

Bulbs

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