We are often asked about replacing halogen bulbs in existing garden lights. Usually these are MR16 type, sometimes G4.

There are 3 main problems:

1. Water - Halogen is inside a sealed glass capsule. LEDs are electronics, and moisture could damage them. Would you leave your smart phone out in the garden?

2. Ventilation - people say "but it's ok, it's a sealed fitting, no moisture can get in" but they don't realise....moisture is already in there. All air contains moisture, and this moisture will condense under certain conditions. Secondly, a sealed fitting by definition has no air flow, and therefore no ventilation. This results in the LEDs overheating.

3. Voltage - LEDs must run on 12v DC. Not 12v AC, like your existing garden transformer. In 99% of cases, this transformer is a "wire-wound" type rather than an electronic type. You may recall early cars had a coil for their ignition. This coil works by energising a magnetic field, then when the power is removed, a collapsing magnetic field sends a high voltage surge to the spark plug. The same happens when you turn off a wire-wound transformer. A high voltage surge goes along the output side, damaging the LEDs. Secondly, these transformers can put out up to 16v under a light load (ie LED) which will damage LEDs.


1. Replace the transformer (case by case)

2. Install a waterproof LED bulb (there is no waterproof MR16)


New LED fittings