"Ian Jackson" wrote in message
...

I don't get it. Maybe I'm a bit thick, but why would the turn-on surge
higher?

Parallel string heaters usually outlast series string heaters, but the
difference isn't due to the heater wiring but due to the surge power from
the heater power supply. Series string tubes are usually powered directly
from the main AC power supply and parallel heaters are almost always powered
through a transformer.

The heater transformer cannot supply a huge surge current.

Frank Dresser