In article ,
T i m writes:
On Fri, 20 Apr 2018 21:55:35 +0100, ARW
wrote:

snip

The
starter is a one shot process.

Agreed, it *should* be but I was wondering under what criteria it
might try to kick in again after say a couple of hours? eg, what if a
ballast was going or a tube etc (except the ballasts have been there
since I fitted the units possibly 30 years ago (could be less [1]) and
they currently have new Philips tubes).

Once the tube is lit it has no further use.

Agreed.

snip

Voltage drop to the house?

Well, that's the sort of thing I am open to but if I understand it
right, the ballast and tube are in series across the mains (forming a
potential divider) and the starter is in parallel with the tube on the

It's not really a potential divider because the tube is far from a
resistor. To a first approximation, it's a constant voltage device,
and to a second approximation, the voltage across it varies inversely
with the current flow. So a reduction in mains voltage will drop the
voltage across the inductor, which will drop the current in the circuit,
and the second order approximation will raise the tube voltage because
of the lower current. This could trigger a marginal starter.

other side of the filaments. The starter is a voltage / current
sensitive device so it *could* be falsely triggered if 1) the voltage
goes above it's trigger voltage [1] and / or 2) the starter is made
such that it's over sensitive (to voltage)?

I know the bottom line is that the electronic (and old Philips
70-125W) starters work, just that the new 4-80W ones don't (or not
fully).

Would you use / have you successfully used 4-80W starters on 70W tubes
do you know / remember please Adam?

Tubes changed their ratings, whereas starters didn't. The 4-80W
starters were originally for tubes up to 5'. 5' tubes dropped from
80W to 65W to 58W over time. 6' tubes dropped from 85W to 70W, with
the 70W tube having a higher tube voltage than the original 85W tube
(so it runs at 70W on original 85W ballasts).

So a starter for an old 80W tube might not work on a current 70W tube.
It would have been more accurate to rate them by tube length where the
original 4-80W starter would have been tubes up to 5', although even
that's not perfect. There was generally enough leaway they worked
outside their ratings, but you hit one that doesn't.

I notice that starters nowadays seem to be 4-65W (which is probably
exactly the same as the old 4-80W starter), 70W is a separate starter,
also a 70-100W starter (which is probably exactly same as old 125W
starter for old 8' tubes).

I think I'll try to pick up some branded (Philips?) 4-80W starters and
see if they work reliably in my lamps.

I would look for a 70W starter or 70-100W starter.

Cheers, T i m

[1] Where the gas (Argon / Neon) in the starter switch capsule get's
hot enough to heat the bi-metallic switch and close the contacts.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]