Back in early 1999/2000 many flurescent tube Ex type light fitting manufacturers suffered from the effect of EOL. The more and more ballasts went broken with no real reason behind. Big players like P, O, etc. started to investigate and came to effect of EoL.

What is EoL?

During the operation of fluorescent light fixtures, the electron-emitting material on the electrodes is consumed. This has the consequence that the energy to release the electrons is increased, and this, in turn, can lead to a higher voltage drop at the electrodes of the fluorescent lamps.

Since the electronic ballast functions as a constant current source, a higher voltage drop results in a power consumption increase. This produces a rise in the surface temperature at the lamp tube ends. The temperatures may exceed the limit values specified for explosion proof apparatus and thereby effect the overall explosion protection.