Hi Specialist. Sorry for the confusion. I have an update of this issue now as well.
First 50W unit was supplied by electrician's supplier. They did flex & plug to the lamp and reported back dim brightness, but don't know if this was intermittent when this was done.
Second 50W unit was again supplied by electrician's supplier and this too had intermittent brightness when installed at my property. I think the electrician measured 230V when dim. However, I did the flex & plug to the lamp (after it was replaced with the third 50W unit) and it was coming with normal brightness (!), even with repeated switch on and off.
Third 50W unit was supplied from JCC by contacting their technical support. This was installed last Friday and now this unit seems to functioning normally (no intermittent brightness).
So overall, this leads me to think that the first and second 50W units were from a faulty batch from the supplier. It's strange that the flex and plug lamp test I did myself on the second 50W unit did not show the problem, contrary to the same test performed by the electrician's supplier on the first 50W unit!
The only other thing I observed was that if the lamps had been off for a while (over a day), then the first switch on would be almost always on normal brightness. Subsequent switch on would randomly be between normal (less often) or dim (more often)
Now, only thing left is that I want to change the manual override with 3 modes (completely on, completely off and PIR mode), instead of 2 (completely on and PIR mode). I read this can be achieved using a 2 gang switch (?).