Light Bulb Spec Testing: How Do We Know 5W = 50W?

At Lightbulbs Direct, we make sure we're only selling the best products, and we want customers to know exactly what they're buying.

Doing this takes a lot of testing, both to ensure bulbs are of the highest quality, and that we can list them with accurate specifications.

The testing sphere

Our testing sphere (pictured below) is used to take all sorts of measurements, from total brightness to the exact colour spectrum given out by a bulb. Not only does this mean that you will know exactly what you're buying, it also helps us to make better recommendations for alternative or replacement bulbs. this is especially helpful with LED bulbs, and the tricky issue of equivalent wattages.


testing sphere


Spotlights are particularly difficult to compare because ones with narrower beams give a more intense - but less well spread - light. We use a plethora of additional equipment to measure beam angles and work out which new bulbs are the best replacements. For a better understanding of spotlight beam angles, we’ve drawn up this explanation here >>

Getting a feel for light bulbs

We don’t just look at the technical stats. It’s all very well having a machine tell us the bulb is good, but how does its light look to the human eye? We have rejected numerous products in the past which have passed manufacturers’ testing but look atrocious, or throw odd shadows across a room, or have an odd tint of green in the light… We take great pride in making sure the product you receive is sound quality and good value, and our decades of experience mean we can spot a good bulb from a bad one.