Interesting subject!!!
Could you add some more data so we can have a better understanding of everything?
Stuff like System type [1 phase, 3 phase], exact rating of each lamp [or lamps if various types], inrush level or cold Resistance level, flashing in sequence, randomly or all at once, overall length of circuits / feeders / subfeeds, available KVA, switching relay's duty rate and other specs, and do the lamps have to be at 100% intensity when on, or can they drop to 90% intensity.
Scott S.E.T.