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Having done a bit of research into light bulbs, here is some useful information if you are deciding to replace your usual incandescent light bulbs with LEDs.
But first, I want to clarify the terminology used to describe the various types of light bulbs on websites because you don't want to be buying the wrong type.
Bulb Types
There are two ways to name light bulbs. The first is by the type of connector (or 'Cap') - the most common being Bayonet and Edison screw.
Bayonet Cap
With its familiar 'push and twist' action, the 'bayonet cap' (also known as BC or B22) is used on most standard light bulbs. It has a diameter of 22mm and two locating lugs.
The 'small bayonet cap' (SBC or B15) is very similar but only 15mm across.
The GU10 spot light has different lugs located in the base.
Edison Screw Cap
The most popular ES or E27 fitting is 27mm diameter and is widely used in both the US and Europe. The Small Edison Screw (SES or E14) is often used for smaller decorative fittings, chandeliers, and appliance bulbs - predominantly in the UK and Europe.
The other way to name bulbs is by the bulb shape.
Common Light bulb shapes
I recently bought a type A to replace a type R and it sticks out of the ceiling a bit more than it should do. I wish I'd found out about bulb types before I bought the wrong one.
Incandescent bulbs (the 'traditional' domestic light bulbs)
 Here is a photo of a blown bulb from our chandelier type living room light. The light has five type B22 cap, G shape (golf ball), 40 watt bulbs in it. The filament has obviously broken. I didn't know that the currently used incandescent light bulb - a wire filament carrying an electrical current in a vacuum - was invented nearly 200 years ago, and approximately 90% of the power is emitted as heat, rather than as visible light. That's pretty inefficient! No wonder they get so hot!
I counted 83 incandescent ('normal') and halogen ('spot') light bulbs in our house, not including table lamps, garage fluorescents and outside security lights. That's a lot of lights including
'standard' E27 Edison screw-ins of type A and R varying from 40 to 60 watts'small' E14 Edison screw types of type R at 28 watts'standard' Bayonet B22 lights of type A and varying wattagesType G 'golf ball' Bayonet B22 lights at 40 wattsGU10 bayonet spot lights mainly at 50 watts
Comparing incandescent and LED bulbs
When all three spot lights on one circuit in our study had blown, I decided to look at longer lasting alternatives.
I discounted CFL (the fluorescent energy saving) bulbs because (as far as I know) you can't get them as spots, they use mercury and take too long to light up.
LED light bulbs are instant-on (like incandescent), are available in a variety of configurations, last over 10 times longer than normal incandescent light bulbs but (currently) cost over 10 times as much. So the cost saving is in the reduced power they use, which is about 1/7th or 1/8th that of incandescent bulbs. So by replacing all three 50 watt bulbs with 6 watt LEDs, we're saving 88% of the electricity right there!
Light bulb power comparison table (approximate)
Incandescent Halogen LED
12-15W 1.3W
25W 25W 3W
30W
40W 50W 5W
60W 60W 7W
75W 9W
100W 13W
As the technology becomes more widely used, I expect the cost of LEDs to come down. One reason they cost so much is that they have to have a transformer inside to convert the 240 volts mains supply down to the much smaller current they need. Maybe in the future, when a house has all LEDs, lighting circuits might have a reduced voltage so that the transformer element of the bulbs is no longer required. I'm speculating though, because I'm not an electrician.
Light warmth
I was surprised to find that most people take for granted (I certainly did) how yellowey our house light bulbs are. That is to say the light from the bulb is quite a lot 'warmer' than pure white. Colder bulbs tend to have a bluer light. The type of light, ranging from red (warm) through to blue (cold) is referred to as its temperature using the Kelvin scale.
LED light bulbs have been criticised for being too cold, and their product descriptions usually refer to them as being 'natural white' or 'warm white'. If you want to emulate the colour of your old bulbs, you need to go for warm or very warm lights with a temperature of around 3,000k or less.
Lamp Color Name Apparent Color Temperature (Kelvin) Common Adjectives Used to Describe the Light
Warm White 2700-3200K Friendly, warm, inviting, intimate, relaxing
Natural White 4000-4500K Neat and clean, Natural tone
Day White 5500-6000K Crisp light, efficient, brightly lit, natural outdoor
Cool White 7000-7500K Bright light, bluish light
Dimmable?
Most LED light bulbs are not dimmable. Those that are dimmable should specifically say so on the product description and are usually a bit (a few pounds or so) more expensive. In a couple of rooms in our house, we have a dimmer switch, and so I will need to buy dimmable bulbs for those rooms. I have read that not all dimmer switches are compatible with LED bulbs, and the amount of light given out is not linear as you turn the switch. That is to say as you turn the dimmer up, the bulb stays off and then suddenly turns on. Replacement dimmer switches compatible with LED lights are sold on the 'net for under £20.
I created a calculator spreadsheet (attached) for working out the cost savings of LED bulbs. (I make no guarantee of its accuracy, but it's a start).
My reports on buying and using LED lights will follow
As light bulbs in the house (and outside of it) need replacing, I'll be reporting on the LED bulbs I buy. I'll be trying lots of different types and comparing them to the ones we already have. Hopefully the information will be useful to anyone else wanting to swap their normal light bulbs with LEDs.
Please reply here with your experiences of LED lights. |
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26-11-2019 03:48:39
