What is Lumen?

A few lightbulbs died and I need to replace them but I don’t know which LED bulb is suitable. I can’t judge by the watts because it doesn’t mean anything about brightness. What I should look at is the lumens of a bulb.

Lumen(lm) is a unit measures the amount of visible light emitted by a lamp per unit of time. It’s mandated to be labelled.

How much lumens do I need?

We will need another unit called Lux(lx), it measures the amount of light per unit area and 1 lx = 1 lm/m2. In order to get lumens, we can multiply lux by the area of the room. You can get lux values for different usages from it’s Wikipedia page or simply use the lighting calculator linked below.

Why LED bulbs burnout?

Some bulbs’ thermal management is clearly insufficient. I took apart the broken bulb, it just sites LED panel on a metal plate and these isn’t much thermal paste between them. Other bulbs use metal base(some are embedded in plastic) will last longer. LED bulbs are much hotter than I assumed, I can barely hold it in my hand. The broken bulb’s plastic base turned yellow due to the heat, no wonder it burns so quickly.

But LED lamps are still way more efficient and reliable than it’s predecessors.

Interesting fact

Guess what’s name of the lightbulb socket? Edison screw! Now you know where the “E” in E26 and E27 comes from.

Okay move along, move along people, there’s nothing to see here!