Doldrums

Gone back to my HP Pavillion, can't remember if it was this one or the Asus I took into Maplins, but they didn't have an adaptor for it

 

Short answer, the table is incorrect.

The efficiency of a light source is measured in lumens per watt. An "old style" (incandescent) bulb will give around 14 lm/w. LED's anything from 10-150 lm/w at present, and even more in the near future.

As an example. An older 100w light bulb would give about 1400 lumens. (100 x 140). A 10w LED could give as little as 100 lumens, (10 x 10) or as much as 1500 lumens. (10 x 150).

Edit: As a thumb rule. A 100w incandescent is typically about a 20w low energy or 10w LED. (According to what I have just read!)

 

That would be about right, but it's not quite that straightforward. As always, the marketing spiel is not entirely honest.

Pros.

LEDs are extremely efficient compared with incandescent lamps. The LED itself is extremely efficient at converting electricity into light, but they can't run off high voltage AC so there are conversion losses in the electronics. The quality of the bulb will have a direct bearing on this efficiency.

The quality of light is superior to that of an equivalent incandescent, and life expectancy of the lamp is much greater. Again, the LED itself is unlikely to fail. They are incredibly efficient (getting into the quantum world of subatomic particles). More likely the electronics that power them are more likely to fail, and the quality of product matters here too.

Cons

Cost would be the main one. They are still quite pricey, though considerably less than they used to be and now well into the realm of value for money generally speaking.

And the biggy (in my opinion) the angle of the cone of light from them. An incandescent lamp will scatter light in all directions. LEDs don't. They actually focus their output quite tightly. Manufacturers actually pack multiple LEDs into one integrated unit, mimicking a classic bulb, misleading people to think they are a direct replacement. While many are, you need to be aware that some will illuminate an area directly under the lamp, but much less so outside of that patch. Again, quality of product makes a difference here.

 

@wiseowl , if you look on the Screwfix site under LED Bulbs , they have every shape of bulb and connector ( bayonet , edison screw etc ). The bulbs give the rough equivalent wattage to an incadescent bulb . Just changed some golf ball type bulbs for the stairs , and I am very pleased with the light out put . I used LAP bulbs which seem to be good quality to price items.

 

Been using screwfix LEDs @ 2 quid each for some time now. Even cheaper with their annual £5 off voucher.