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How to choose LED lamps and fittings - avoiding the myths

These guidelines have been written to provide buyers with the information they need to correctly select LED lamps to replace existing filament lamps, and to choose new LED light fittings. Many suppliers and manufacturers make misleading claims about their products, to avoid these myths we strongly recommend you familiarise yourself with the issues described below.

This article is split it into two parts:

Cut to the chase
The bare minimum you need to know to choose the right LED lamps or LED light fittings.

Tell me more
A more detailed explanation of the issues. Highly recommended reading if it is important to select the best LED lamp or fitting.


1. How warm does the light need to be? - the colour temperature (K)

2700K : If you want to match the colour of a traditional filament lamp

2900K-3000K : If you are happy with a slightly colder light than a traditional filament lamp

4000K-5000K : If you want a cold white light similar to daylight

2. How bright does the lamp/fitting need to be? - the number of lumens

>450 lumens - If you want to match the light output of a good quality 50W GU10 (230V) lamp

>800 lumens - If you want to match the light output of a good quality 50W MR16 (12V) lamp

3. What angle/distribution of light do you need?

10-20 degrees - To highlight artwork and create pools of light

25-45 degrees - For general illumination

50+ - For a wide spread of light

4. How accurately do colours need to look? - colour rendering index (CRI)

80 - If you don’t care how accurately colours appear under the light

85+ - If you want the colours to look reasonably accurate

90+ - If it is important for the colours to look as accurate as possible

5. Does the LED lamp or fitting need to be dimmable?

For MR16 12V lamps check which transformers they are compatible with.

For MR16 12V and GU10 230V lamps check they are compatible with the dimmer switch or lighting control system you intend using.

For LED fittings supplied with their own drivers there are fewer compatability issues but you should still check compatibility with the dimming system you are using.

6. What quality of lamp/fitting do you want?

Go for the highest quality LED lamp/fitting that your budget allows. You will benefit from needing fewer fittings in the ceiling to create the same amount of light, a better quality of light, longer life spans, and fewer compatibility issues. Choose leading brands and be prepared to get what you pay for.



We wrote this article because a customer asked us to. They had tried to find a single comprehensive unbiased article online and couldn’t. And when we looked ourselves nor could we. It was also surprising how many articles were simply wrong on some of the facts. Even ones from reputable sources. Sometimes this was clearly because the writers had a vested interest in particular brands and so naturally their advice was skewed in their favour. At WowLighting we recommend whatever is best on the market and regularly recommend new brands, even, and often, ones we have no relationship with.

Beware Manufacturer’s Claims! 2 does not equal 4!

Sadly many manufacturers are less than totally open with their claims of equivalence. A very well known manufacturer, popular with electricians, claims that their 7W LED fitting is equivalent to a 50W Halogen. It isn’t! Their fitting produces 470 lumens of light. 50W halogens typically produce 800 lumens or more (depending on make). So how can the manufacturers possibly make their claim of equivalence? It is easy, they are not saying that their lamp produces the same total light output as the 50W halogen. They are actually saying, but not making this clear, that their LED lamp produces the same light at the centre of the beam. I.e. if you stand immediately underneath the lamp in the ceiling the LED lamp will be as bright (or even brighter) than the 50W halogen version. But wait, surely that’s ok then? Well no not really and no not at all! If you replace 50W halogen lamps with these comparatively low lumen LED lamps your room will be darker. No ifs and no buts. Darker.

Lumens not Watts

Lumens are THE definitive measure on how much light is produced. Not Watts! A statement such as “A 5W LED is equivalent to a 50W halogen” is completely meaningless. It is the actual amount of light produced by a product (the lumens) that is important, not how much energy is used to create it. This by the way is also true for filament lamps where one manufacturer’s 35W halogen can produce the same amount of light as another manufacturer’s 50W halogen.

When checking lumen figures for a product do make sure it is the post optic lumens and not pre optic figures you are looking at as the lenses used in some fittings can absorb quite a bit of the light.

You should also compare the lumens of products at the same colour temperature (K). Comparing one fitting with a colour temperature of 2700K with another with a colour temperature of 3000K is not comparing like with like. Generally, for a particular lamp type, the 3000K version will produce more light than the 2700K version.

Equivalent to a 50W Halogen…..but what type!

Ok, so even if an LED fitting is equivalent in light output to a 50W halogen what does that mean? There are two types of 50W halogen. Low voltage (12V) and mains voltage (GU10). They are different. They produce different amounts of light. A 12V halogen will, depending on the make, give out @40% more light than a GU10 halogen. This means you need @14 GU10 lamps in a ceiling to get the same light output as 10 12V lamps! So, if you are looking to replace a 12V halogen lamp with an LED lamp or fitting it needs to be equivalent to a 12V halogen and not a GU10 halogen.

Colour Temperature (K)

Do you like cold light or do you prefer the warm light produced by traditional filament lamps? To match the colour of light from a halogen lamp you should look for a colour temperature (K) of 2700K or at worst 2800K. Many budget LED lamps have a colour temperature of @3000K. The really cheap ones tend to have a bluish colour.

You should try, when mixing light fittings in a room, to use the same colour temperature throughout or you will create an effect that looks mismatched and wrong. Retrofit LED lamps, LED fittings, LED tape and LED strips should ideally all have the same colour temperature. If some of the fittings you intend using are only available at 3000K you would do better to make all the lamps and fittings 3000K rather than only have some that are 2700K as this will look odd.

Colour Rendering Index (CRI)

Do you have artwork you want to show off? Or food you want to look natural in colour? Or you want to see exactly how your makeup or clothes look? Then you need to take care of the CRI of the lamp you choose. Don’t accept anything with a CRI lower than 85 and preferably go for something that is 90+.


One of the biggest problems with LEDs at the moment is their compatibility with dimming equipment, and for retrofit 12V LED lamps with transformers as well.

For retrofit 12V LED lamps you cannot be sure that they will work with the existing transformers you have. You should always either test the lamps with the transformers you have, or better still replace the transformers with ones that have a minimum load of 0 Watts and are specified to work with retrofit LEDs. Even then you should check compatibility before committing to a purchase. The transformer issue does not arise with GU10 LED lamps or LED light fittings that come with their own driver.

Some dimmer switches work with retrofit LED lamps but many don’t. The ones that don’t either won’t dim or will cause the LEDs to flash when dimmed. Unless you are sure your dimmer switches are compatible you should consider replacing the dimmer module in the light switch with one that is designed to work with the widest range of LEDs. Again you should check or test compatibility.

If you are using a lighting control system to dim LED lamps you should check compatibility with the lighting control system’s dimmer module. If possible choose a system that uses Universal Dimmer Modules that are known to work with most LED lamps. Universal dimmer modules have inbuilt intelligence that adjusts how the load is dimmed according to what type of lamps are being used.

You should never try to mix different types of lamps on the same dimmable lighting circuit (e.g. filament with LED) as intelligent dimmers will struggle to determine the best way to control the load.


The saying you get what you pay for has never been truer than it is with lamps. And particularly with LED lamps. There is a direct correlation between price and longevity of lamp, and price and quality of light produced. At WowLighting we always try to find the lowest cost fittings that we can that are technically acceptable, these of course never, or virtually never, turn out to be the cheapest. Imagine you are buying fuel for your car and that petrol garages sold a special budget fuel. It works, in as much as it makes your car go, but you don’t get so many miles per gallon and when using it your car feels as if it is not running very smoothly. Would you buy this fuel? I would imagine very few people would. The same good judgement needs to be applied to LED lamps.

Retrofit LED or new LED fitting?

All retrofit LED lamps (e.g. those intended to replace halogen MR16 and GU10 LED lamps) are severely constrained by the physical size limitation of the lamp. This in particular affects the size of the heat sink and the ability of the lamp to dissipate the heat produced by the LEDs. For the designers of the lamp it is a battle between creating lots of light and cooling the lamp sufficiently to create an acceptable product life. All things being equal, and if your budget allows, you should use replacement fittings instead of retrofit LEDs as these have large and very effective heats sinks, create more light, last longer than retrofit lamps, and you will need fewer of them.


The light sources (diodes) in LED lamps can be very very bright. The glare from an LED lamp is way harsher than that from a 12V halogen for example. You should bear this in mind when choosing LED fittings. To reduce the glare bombs in the ceiling we recommend using fittings with recessed lamps (sometimes referred to as dark light downlights). These will be much more restful on the eye and reduce the appearance of ‘ceiling acne’.

LED tape

The biggest mistakes in choosing LED product are often made when choosing LED tape for edge lighting or wall/ceiling washing. There are so many things to consider. The reason that LED tapes vary so greatly in price is that they vary greatly in performance and function. Before selecting a tape ask yourself:

(1) Do I want discreet points of lights or a smooth diffuse effect? The spacing between LEDs, the optics that spread the light, and the existence or not of a diffuser will all affect how diffuse the light beam is.

(2) Am I after a purely decorative effect (low lumen output LED tape), or do I want to wash a wall or ceiling with lots of light (high or very high lumen output LED tape). For the same manufacturer, and for the same type of product, it is usually the case that the more a product costs the more light it generates.

(3) Do I want the colour of light produced to match that of the other light fittings in the space (it can look odd if it doesn’t). If your other fittings use filament lamps then go for a colour temperature of 2700K or failing that 2800K. If there are other LEDs in the room then match to the same colour temperature.

(4) What beam angle do I need to get the effect I want? If you are after an edge effect a narrow beam may be suitable, if you are after a long wash of light you may need a wider angle. It depends also on the mounting position of the tape and the viewing angle.

(5) Does the tape need to be IP rated for use in bathrooms or outside? Many LED tapes are available in IP65 versions suitable for wet locations.

(6) Does the tape need to be dimmable? If so you will need to check a dimmable driver is available.

Use this information to tell the supplier exactly what you are after so they can guide you towards the correct product.


If you care about the quality and appropriateness of the LED lamps and fittings you buy then you will need to take account of all of the issues described above. There are a lot of things to consider so we advise you discuss these issues with your supplier to make sure they fully understand what you are looking for. If you would like WowLighting to help you find the right LED lamps or fittings please contact us using the link at the top of this page.

WowLighting aims to make the use of a lighting designer affordable on all projects, no matter what the budget. Call us to discuss your needs and we will tailor our services accordingly. We even offer free advice over the phone!

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