on 28/04/2018, Brian Gaff supposed :
Yes some are like that other seem to kind of fade on. I don't see them
nowadays but our studio has quick start electronic ballasts and apart from
blowing one after 10 years they have been fine.

I'm not sure whether it is a quick start or slow start up E-Ballast. It
is a b.a.g BCS 54.1FR