If you’ve still to upgrade your halogen spotlights to LED, time is running out.

In September 2016, the European Commission directive banning the manufacture of ‘high-energy’ halogen spotlights came into force. These bulbs are now becoming increasingly difficult to find as retailers sell through the last of their stock. This guide will tell you everything you need to know about replacing Halogen MR16s with LEDs.

Fortunately, upgrading Halogen MR16s to LED is usually a painless affair, as most LED bulbs are now designed to retrofit to existing light fittings. All you have to do to swap your old bulbs out is remove them from the light fixture and fit the new, shiny bulbs in their place.

The same goes for low voltage spotlights, but as they use transformers to convert mains voltage to a suitable lower one, you have to be careful to install the right LED bulbs.

Replacing Halogen MR16s with LEDs

If you have low voltage halogen bulbs installed with a transformer, the first thing you need to do before replacing Halogen MR16s with LEDs is to find the transformer’s maximum load. You should be able to find this on the body of the transformer itself, in the form of a ‘VA’ number. This VA number will either be fixed, or it will be a range (e.g. 10-60VA).

These numbers tell you the maximum wattage that the transformer can carry. For example, a 40VA transformer can handle up to a 40-watt halogen bulb, while a 10-60VA one can carry between 10 and 60 watts worth of light bulbs. Some transformers might just carry one individual light bulb, while others might be able to carry several lower wattage bulbs in a series.

At this point, it’s important to note that if it is a halogen transformer, this maximum load applies to halogen light bulbs only. For example, if you have a 40VA transformer for halogen light bulbs, you should not install 40-watts worth of LED light bulbs. This would overload the fitting and potentially cause a safety issue.

Fortunately, there is an easy way to find the right low voltage LED spotlights.

Equivalent wattage – swapping halogen MR16s for LED

The natural energy-saving properties of LED light bulbs means that they can offer the same brightness of a halogen equivalent, but using only a fraction of the power. A 5W LED spotlight, for example, can offer the same brightness of light as a 35W halogen spotlight.

The 5W LED bulb is the ‘equivalent wattage’ of the 35W halogen bulb. You can usually find this equivalent wattage listed with online product details, specification sheets (where available), and on the product packaging.

When replacing Halogen MR16s with LEDs, it’s important to use LED bulbs of equivalent wattage to your existing halogens. This will ensure that the transformer can still handle the load safely.

For example, if you have one 35W halogen installed in your kitchen, ensure you swap it for 35W equivalent LED. The actual wattage of the LED bulb may vary, but the equivalent wattage must be the same as your current halogen bulbs. For example, you might find both 5W and 6W LED bulbs that have an equivalent wattage of 35W; both of these would be fine to replace 35W halogen bulbs.

This is only getting more complicated as LED technology gets ever more energy-efficient, but as long as you remember to look for the equivalent wattage, you will find the right LED spotlights. We’ve finished our guide off below with a quick ‘cheat sheet’ to help you remember all the technical terms discussed above. See our in-depth glossary of lighting terms for even more information.

Equivalent Wattage

A term used to compare LED light bulbs with their incandescent alternatives. An LED light bulb with an equivalent wattage of 35W is a direct replacement for a 35W incandescent light bulb. This is different from a light bulb’s stated wattage (see below).

Halogen MR16 Spotlights

Spotlights are ‘directional’ light bulbs that emit light in a focused beam. Halogen spotlights are a form of incandescent bulb that use a tungsten filament and a mix of inert and halogen gases to produce light. The European Commission directive in September 2016 banned the manufacture of this type of power-hungry spotlights.

LED Spotlights

LED (light-emitting diode) light bulbs are the most technologically advanced and energy-efficient bulbs available. They last many times longer than halogen bulbs, produce the same amount of light, but use only a fraction of the energy. Most LED light bulbs can be used with existing light fittings (this is called retrofitting).

Low Voltage

Most light bulbs operate off mains voltage (see below), but some light fittings are designed to be lower voltage. These are most commonly used in integrated kitchen fittings, where space is at a premium and smaller light bulbs are a necessity. Low voltage light fittings often need a compatible transformer (see below) to convert mains voltage to the correct, lower voltage. Most low voltage spotlights will be between 12-24 volts.

Mains Voltage

The voltage of a building’s electrical circuits. in the UK mains voltage was 240 volts until late in the 20th Century, when it was changed to 230V to match other European countries. As this comes with a +10% tolerance, electrical equipment with a stated voltage of 240V is still fine to use on standard UK mains circuits. The majority of light bulbs are for use with mains circuits, except for ‘low voltage’ bulbs, which must be used with a compatible transformer (see below). All low voltage bulbs should be clearly stated as such on product listings and packaging.


Bulbs that operate on a lower voltage than 230-240V must be used with a compatible transformer when installing on UK mains circuits. The transformer converts mains voltage to a lower voltage suitable for the bulbs, ensuring they function as designed and preventing damage to the bulbs and/or light fittings.

VA rating

The volt-ampere (VA) rating is the maximum load (in watts) that a transformer can safely carry. For example, a 40VA transformer can handle up to 40-watts of electrical equipment, while a 10-60VA one can carry between 10 and 60 watts worth. Installing low voltage LED bulbs on a transformer designed for halogen lighting requires you to find the equivalent wattage (see above) for the LED bulbs, so as not to overload the transformer.

Wattage (or Stated Wattage)

Denotes the rate of power consumption of electrical equipment. A higher wattage equals greater power consumption. LED light bulbs have a stated wattage and lumen output, as well as an equivalent wattage (see above).

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[…] Replacing Halogen MR16s With LEDs – Everything You Need to Know to Make the Switch […]

John Dowell
John Dowell

I have 2 gu4 halogen bulbs in my fireplace. I’ve tried to replace with two led bulbs. When I install the new led bulbs they dont work. If I leave one led bulb in and install 1 halogen bulb in the led light lights up. The halogen bulb does not.

Why is this ?


I have high voltage halogen bulbs installed with a transformer. Do I need to change the transformer if I want to retrofit new LED lights into existing fixtures?

Mat @ Lightbulbs Direct

What voltage is high voltage?

The LED light bulbs we sell operate on a UK standard 240V AC, and the light bulbs have a built-in transformer to change this 240V to the LED required voltage.
We also sell 12V light bulbs, but these need to be used in conjunction with a 12V transformer.

Tom Kilgllen
Tom Kilgllen

The LED bulbs I bought seem as though they will be fine in my current MR16 housings. The existing lights are running through a Low voltage dimmer.
My question is – I would think I need to leave the low voltage dimmer instead of switching it to an LED dimmer. As far as I know, a standard LED dimmer is not low voltage. Do they even make an LED low voltage dimmer? Do I need it?

Thank you!!

Mat @ Lightbulbs Direct

Hi Tom, this very much relies on the quality of your transformer. The dimmer switch acts by cutting the power on/off very rapidly, but it is down to the response of the transformer in how this is relayed to the MR16 lights. My only advice is to take advantage of a supplier’s returns policy to try some products out on your own set-up. Remember to keep the packaging in a re-saleable condition and understand that you will probably have to cover the cost of return postage if you order from an online retailer.