GU10 MR16 LED SMD & Candle Low Energy Bulb Buying Guide

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This energy saving light bulb buying guide is under construction and constantly changes as energy saving bulb technology moves forward.

Different light bulb fittings, caps and bases. Below are the most common types of energy saving lamp fitting or base for the UK and European market :


MR16 (GU5.3)

BC B22 bayonet cap

SBC B15 small bayonet cap

SES E14 small edison screw

ES E27 edison screw

MR11 (GU4)

Material from this energy saving lamp buying/advice guide is our intellectual property and must not be copied without our permission.

Energy Saving Bulb types

Normal low power LED energy saving bulbs have a very long life (often between 12 and 25 years or 25,000 hours) and they use a very small amount of electricity.  These lamps are normally used for mood lighting, accent lighting or low level lighting.  The lower wattage power saving LED bulbs of this type are standard size and shape and have from 15 to 21 LEDs per bulb (once you get above 21 LEDs per bulb the GU10 low power LED bulbs get longer than a standard GU10 bulb).  They normally range from 1.3w to 3w in warm and cool white and are very popular for effect lights or if you don't need bright light to see by you can also buy a version which constantly changes colours with red, green and blue LEDs.  If you need bright light to see by rather than mood or accent lighting look for the other types of power saving light bulbs (see below)

LED and SMD LED bulbs tend to contain no mercury

SMD (Surface Mounted Diode) LED GU10 bulbs are the latest and the best thing for bright low wattage lighting.  You can now get a GU10 4.5w SMD by Eveready with equal light to a 50w halogen bulb.  They are totally standard size and shape yet still a genuime 50w equivalent light.  They are also a 3000k white light which is a warm white but not too yellow or pink.  We would recommmend this type of bulb as it is the best and brightest standard size bulb and by far the best thing to replace a 50w halogen bulb.  Unfortunately they are not dimmable.

Super or High Power LED GU10 energy saving light bulbs are the next best way to go for bright light if you want a long term option and can get your head around the initial outlay and the fact that it will take a few months for them to pay for themselves.  It's hard to see bulbs as a permanent fixture when they have always been classed as disposable items but the super long life speaks for itself, cutting down on bulb and maintenance costs.  You can use these lamps in areas where the lights are on constantly or for long periods and thus save the most money after the SMD bulbs, but not everyone likes the look of the Surface Mounted Diodes on a SMD bulb.  They use only 2 to 7 watts per bulb, the best selling being the 3w and 4w models, with 3 LEDs per bulb (they also have a long life from 12,000 to 25,000 hours depending on the brand and model).  The LED emitters are very bright and use very little electricity.  The only downside of these bulbs is the high initial cost price but they pay for themselves many times over time.  Until I saw the brightness of the SMD bulbs I would have said that these are the latest technology and the future of low energy lighting.  Prices are coming down - a couple of years ago these bulbs cost £25 to £30 each for genuine branded bulbs.  You can buy them from £10 upwards and still get a branded bulb these days.  They run from 2w up to 7w or so, with 2w to 4w being totally standard size.  A 4w GU10 with 3 high power LEDs per bulb can be used to replace 50w halogen GU10 bulbs and long term you can always take the bulbs with you if you move house or you can use them as a great selling point if you sell your property and it will improve the energy rating.

Buyer beware :  There are hundreds of small Chinese factories producing shoddy GU10 high power LED or CFL bulbs that only last about a year if you are lucky and yet they state a 10 to 25 year life.  Please remember there are lots of internet sellers importing importing these cheap GU10 bulbs a few boxes at a time from China totally missing out the CE safety approval and European and UK quality checks, as a rule of thumb.  If they come in a plain white box and there is no branding or importers details on the box then they are most likely illegally imported - the lifespan will be dubious to say the least and there is also a potential fire risk if the bulbs and circuits haven't been manufactured to proper European safety standards.

GU10 bulbs, CFL and LED energy saving bulbs are actually quite complex and have circuit boards, chips, resistors and ballasts, etc, in them.  They aren't like the old type of bulb where the only thing that can go wrong is that the bulb filament blows.  Badly made LED and CFL bulbs can overheat and even catch fire so please take this bit of free advice on board and don't encourage illegal imports by buying white box goods.  Stick to genuine brands.

CFL GU10 (Compact Fluurescent) energy saving GU10 and Candle Bulbs.  CFL compact fluorescent GU10 and candle bulbs offer great value for money and a cheaper way to start saving energy although they have some differencces.  This low energy light bulb type are a great way to save 70-85% power, they are a good value for the lumens or light output and normally have a long life (6 - 10,000 hours is normal).

CFL GU10 light bulbs have a mini compact fluorescent tube inside.  These (until the 4.5w SMD bulbs came out recently) are the most commonly sold bulb for room or 'ambient' lighting rather than mood or accent LED lighting.

Bulb length in these CFL bulbs range from 58mm to 80mm length including pins so they are longer than a normal GU10 halogen bulb.  You can buy 7w, 9w, 11w up to 13w in CFL GU10s.  The best CFL bulb replacement for a 50w halogen GU10 is an 11w or a 13w and these wattages need a longer body bulb.

You can also buy CFL energy saving bulbs in candle, GLS (globe) and spotlight/floodlight fittings amongst others.  The downside of all this great saving is that CFL bulbs can take a few seconds to warm up if they haven't been on for a while.  All other main types shown here come on instantly at full brightness.

Also, some CFL energy saving light bulbs will only fit in open fronted or adjustable bulb GU10 holders due to the longer length.

Another downside is that even branded CFL bulbs contain a tiny amount of mercury (if they are illegal imports they won't be RoHS compliant so could have more mercury) so if you break one it is recommended you put the bits in a bag and dispose of it properly at the council tip or with your bulb supplier rather than it ending up in landfill.

You can get short body and long body types.  The long body GU10 CFL comes in 7w, 9w, 11w and 13w and short body CFL bulbs come in 7w or 9w (NOTE : 9w short body can have overheating problems due to being in a shorter body and 9w being a lot for a short body, they are better in open fittings.  The long body doesn't have the same problem as there is more room to disperse the heat.

Halogen : Halogen GU10 and candle dimmable ebergy saving bulbs have the advantage of being dimmable and very bright (GU10 halogen 50w equivalent power saving bulbs are a direct equivalent to a 50w normal halogen GU10 bulb and you can get candle halogen energy saving light bulbs from 40w to 60w equivalent in these fittings : B15 SBC, E14 SES, B22 BC and E27 ES caps.

These halogen type bulbs give you 25% to 35% more light per watt used.  Halogen energy saving bulbs give off more light than a normal incandescent light bulb and last a lot longer.  The downside of halogen GU10 energy saving bulbs is that you don't save as much electricity as with a CFL or LED power saving bulb but on the upside they have the advantage of being exactly the same shape and size as a standard GU10 bulb.

Halogen energy savers are fully dimmable, they come on instantly at full brightness and they will fit into any GU10 light bulb or lamp fitting.  These bulbs will usually last twice as long as a normal halogen GU10 or candle light bulb.  They come on instantly at full brightness so there isn't any compromise with these in comparison to a normal halogen GU10 or candle bulb as far as light and fitting goes.  The great feature point of these is that they only cost the same as a normal GU10 or candle halogen bulb plus you save 20% to 30% power and they last twice as long.

No compromises whatsoever!  A very popular GU10, MR16 or candle light bulb choice for those with dimmer switches.

If you are fitting new light fittings.  If you are installing new GU10 fittings and wondering what type to fit, if you can try and opt for an open fronted GU10 bulb holder where possible because then you can use any light bulb you choose from the whole GU10 bulb range.  If you already have enclosed GU10 down lights or spotlights with glass covers already and there is no room in the holder for a longer bulb then the choices are more limited and you will have to go for a standard size light bulb like the GU10 SMD 4.5w 50w equivalent type.

High power GU10 LED or SMD LED or the halogen power savers are the best for when you need a standard size bulb.



Colour temperature of LED and CFL energy saving light bulbs is measured in Kelvin expressed as "k" and bulbs tend to range from 2700k white to 6400k white and k refers to the shade of white emitted from LED and CFL energy saving lamps.

2700k - 3000k is a warm white light colour similar to the colour of sunlight, very slightly yellow in hue (most normal incandescent bulbs are 2700k to 3100k so this is the colour of light most people are used to).  It is a soft white and many people used to normal (non energy saving) bulb light will prefer this shade of light for living areas as it has a more "relaxing" feel to it.

3500k is a shade of light most used by the Eveready brand of energy saving CFL bulbs and it is in between warm white and cool white but is whiter than a standard incandescent light bulb.

5000k - 6400k is a cooler white and known as cool white or daylight white.  This is a bright white and you do tend to get a little more light (about 10% more lumens) from the bulbs per watt of power used.  To help describe the colour, they are a similar colour to the 4 foot fluorescent strip lights you see in workplaces and factories.  It is a cool white and is very popular in bathrooms, kitchens, public areas, shops, work areas, hair salons, etc.  It gives great colour rendering and is a bright white light - some people think it's too harsh a light for relaxing areas.



Here are some real life asked questions and if anyone wants to add to this we can make it part of the buying guide.  We all know what a nightmare choosing these bulbs so I am hoping to help everyone out there by eventually making "The definitive buying guide to GU10 energy saving bulbs". 

I can only tell you what I think I know and this is not legally binding in any way, shape or form.  It's my own opinion from years of selling and feedback from customers and I am still learning every day.

Here we go with the real life questions then.

"I am looking for candle CFL energy saving bulbs in a cooler white - do they exist?"

Yes, you can get candles in 3500k white but it's not as blue as 6400k cool white.  3500k white light is whiter and brighter than warm white but not blue like a cool white.  I have never seen candle shape in anything cooler than 3500k but they may well exist.  I hope that helps, we normally try and explain it by saying that warm white 2700k is at the yellow end of the white light spectrum and so is the colour of sunlight ie, slightly yellow, 3500k is in between warm and cool and cool white has a slight blue tinge to it as it's at the blue end of the visible white light spectrum.

"I was looking to replace the current GU10 50w halogen lamps, what would you recommend is the nearest like for like light output?"

If you have open fronted GU10 spotlights then you are in luck.  For open fronted spots or down lights you can use all the types above depending how bright  you want, but in CFL to replace 50w you want the 11w or 13w in either cool white or warm white depending which colour of white light you prefer.  If you can afford high power LED bulbs then they are the way to go for long term savings.

Flush ceiling mpounted ones are harder to get energy savers for, you are stuck with the halogen energy savers (very cheap and you save 20% power) or with high power LED bulbs which are expensive to buy originally but are by far the biggest money saver long term.  The bulbs are about £10 - £25 each (depending how many you buy at one time and the wattage) each but they only use 2 - 4.5w power so you save about 90% power and they last many years.  By replacing a few 50w bulbs you save hundreds of pounds over the bulb's lifetime and although high power GU10 LED bulbs cost a lot to buy in the first instance they save you the most.

They save the most money long term and I will take them with me if I move, you really can't beat them.

The (much cheaper) GU10 halogen energy savers are also standard size and shape and also dimmable but you only save 20% power with these.  The bulbs are very cheap, though, about the same as a standard 50w halogen GU10 price wise.

"What does SES E14 mean, please?"

Hi, as you probably know Thomas Edison (arguably) invented the light bulb and his first bulbs were ES fittings which stands for Edison Screw.  They call them E27 and the thread is 27mm wide.  SES stands for Small Edison Screw and is E14, the E being the screw fitting and the 14 being the millimetres of thread so an SES (Small Edison Screw) or E14 has a 14mm thread, a BC (bayonet cap) bulb is B22 (22mm diameter cap) and a SBC is B15 (15 mm cap) so that's the four most common fitting types :  ES, SES, BC and SBC

"I'm starting to get an idea of the warmth of a white light bulb but I would just like to know the difference in the different Kelvin (k) values, please?"

To help you with colour temperatures here is my own opinion :

2700k warm white is like a sunlight colour (some are starting to call it "soft tone" nowadays) and those are distinctly yellowy in colour like the colour of sun with a clear sky through a window onto your window sill in a morning (sort of the colour of a normal old traditional pearl 60w house bulb).

3000k is also a warm white but a slightly purer (less yellow) white and is very popular.

3500k is in an "in between the two" white but still a distinctly whiter shade than a normal house bulb and you get about 10% more lumens per watt than with a 2700k.

6400k is almost blue-white in hue like a daylight white on an overcast day.  It's so far up the spectrum the light is very white like the colour of a 4 foot fluorescent tube as you see in factories and schools, etc.  You get about 15% more lumens per watt than with a soft tone 2700k lilght but it's not a light for relaxing.  It's good for kitchens and bathrooms, though, where you don't need the ambience.

As you go up the spectrum in light shades you also get slightly more brightness (eg, a 6400k bulb will give out 15% more lumens than a 2700k lamp using the same wattage and fitting).

Many customers buying for their homes go for the 2700k for living areas and white shades like 3500k and 6400k for work areas, bathrooms, kitchens and public spaces, etc.

"We have had a truly bad and very experience with GU10 LED bulbs, can you help?  Poor light levels despite claims, poor beam patterns and the final straw was 7 out of 10 failing catastrophically in under 2,000 hours ie, not much better than a good quality incandescent.  We seek GU10 LEDs again, white, genuinely close to 50w of halogen ans genuinely long life.  What would you recommend?  Any advice sincerely appreciated.  Thanks.  Mike (last name removed), Electronic Reliability Engineer.

Sorry to hear you had problems in the past but technology is improving all the time.  I should imagine the ones you bought were what is known as "white box" goods, illegally imported from China.

If you go for a branded bulb it will have genuine safety approval as brands have to follow all the laws and rules.  In the past most of the bulbs for sale on the internet were and often still are fakes or unbranded Chinese copies with fake CE approval marks on them.  It's amazing how many dodgy bulbs there are out there.  I would say 80% of what's on websites is either fake or unbranded, you can't even make genuine European approved bulbs for the prices they sell them at and anything sold in a plain white box has been illegally imported and might not be safe.  They sell them in white boxes with no brand so they can't be traced back to the importer who could be liable for a house fire for instance.

"Why are some CFL low energy saving bulbs larger than normal light bulbs?"

This is purely down to the electronics and tube in the compact fluorescent candle bulb.  They don't just have a glowing filament in them lilke a normal candle bulb, when you take them apart there is a round circuit board with a little transformer coil, ballast, a couple of capacitors and resistors and some wiring and sometimes a chip.  Plus you have the fluorescent tube itself, this means they can't get higher brightness without bigger components.  This then means a larger bulb, however if your fittings can take a longer bulb then CFLs are a great light provider at a low price.

"Looking for GU10 energy savers, I presume the extra length does not matter as long as they can fit inside the ceiling void?"

All energy savers can be used in enclosed holders or recessed holders if they will fit as long as they are fitting in such a way as to avoid electrical or fire risk as you would with normal GU10 halogen bulbs.


Thanks for reading our energy saving bulb buying guide.


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