Hi

I have following issue to get clarified,

I installed a T5 lamp and measured earth terminal, voltage (without connecting the earth wire of the wiring system) wrt system earth it was 134V ( more than 50V)

(ballast is new and same value got for the another same brand ballast)

when I measured earth leakage current it was 0.3mA

Is it accepted the above voltage ?

Since they likely have front end mains filters I would be surprised if a floating ground connection did not read around 50% of supply. Connect the ground and all will be well.

Nothing remarkable at all.
Most class 1 appliances and components thereof such as lighting ballasts will exhibit broadly similar results.

This does however show the un wisdom of putting large lighting installations on RCDs.
At 0.3ma earth leakage per ballast, 50 ballasts would be about 15ma total leakage which is approaching the threshold of nuisance tripping of common RCDs.

Lighting circuits do not allways need RCD protection, but if this is required, it should be an RCBO per final lighting circuit, with perhaps no more than 20 ballasts per circuit.