I have found that certain sizes/wattages of preheat lamps exhibit an instant-start behaviour when used with glowstarters - they just light up straight away before the starter has a chance to activate!
This is an undesirable characteristic for two reasons, firstly it doesn't flash (thus  very boring) and secondly it must be causing damage to the electrodes as they are not designed to be  holding a discharge without having been preheated first so will reduce lamp life when this happens.

The main culprits of this are the 4/6/8w T5's, 15w T8, 20 - 40w T13's. Also the 18w PL-L frequently does it.

Anyone know why this happens!?  And how can I make the lamps behave properly!!

Perhaps it is because the line voltage going through the ballast when the lamp is cold is enough to make the lamp start before the starter even has a chance to activate. Or it could be something wrong with your line voltage

I do live on the edge of a large town, right near to where large pylons bring in the power cables, so yes voltage could have something to do with it (I think my next purchase should be a voltage meter).
If this is the case it may also explain why I seem to burn up cheap CFL's so quickly!!

If your line voltage is consistently high, you can contact your local authority and they may be able to do something about it.

My work has a 230V supply, never less than 230V, but never more than 232V, mainly because there is a shared transformer in the rear of 500kVA, in parallel with a 1 MVA one 50m away via a nice set of 800A fuses. We are fed from the bus bar by a set of 200A fuses, peak load in summer is max 200A per phase, minimum in winter is 30A. We do have a lot of airconditioning units though.................

Home varies from 225V to 234V, depending on load, though there are large interruptions due to "Load Shedding" AKA as rolling blackouts. Wreaks havoc when the big cold load comes back on, CBI, local office, says they are experiencing high sales of earth leakage units that are faulty, as well as a large amount of MV switchgear that is not rated for daily switching and burns out, oftimes spectacularly.

Re:  I have found that certain sizes/wattages of preheat lamps exhibit an instant-start behaviour when used with glowstarters - they just light up straight away before the starter has a chance to activate!


Is your line voltage 230-240 volts and use reacter ballasts? I have found that 230 volts open lamp circuit and higher to be high enough to cause instant starting in many lamp sizes under the right conditions. Sometimes this starting won't be complete either. The lamp will be "cold cathode" on one end until starter hopefully kicks in to correct this. One way to try to alleviate this is to somehow increase the distance between the lamp bulb and the metal reflector/ballast cover, as this creates a capacitive coupling to aid in lamp starting.  In the U.S., reacter ballasts aren't usually a problem with this, as the line voltage is 120v. (For 4 watt up to 22 watt). And the preheat in the larger wattage has step-up ballast to about 200-210 volts in most cases.

Incidentally, with the 120 volt reacter, I see starting problems sometimes with 20 watt lamps where the starter starts up lamp, but not fully, and lamp then rectifies and starter doesn't correct. If left running in this condition, the electrode that is running "cold cathode" will eventually darken and shorten life expectancy.

Is your line voltage 230-240 volts and use reacter ballasts?

Yes to both!
I have also noticed that sometimes lamps do rectify briefly when they self start and if a lamp does this regularly then one end goes black and the tube dies much sooner. The F8T5's are the absolute worst culprits here - I've lost count of the number of these that have needed replacing after only a few months (which is why I don't use them much any more).

As for the metal casing, this does seem to be significant as most of the lights that do this have grounded metal right next to the lamp.

I have found a kind of solution to the problem by using Electronic Pulse Starters. Unfortunately they are very expensive ($5.99 each compared to $0.50 for a glowplug) and are very boring as they don't flash the lamp. But they are useful to preserve the life of lamps which are costly to replace, for example specialist aquarium or Germicidal lamps.

Never tried those electronic pulse starters! How do those behave when lamp reaches end of life? And can lamp failure cause starter failure eventually?

A Pulse Starter is a monostable (one-shot) timer circuit which preheats the electrodes via a power transistor, holds it for about 2-3 seconds then opens/closes rapidly for another second before staying open.
The principle is that the electrodes are heated for a set time which is known to be enough for any of the tubes in its rated range, then works with the series inductor ballast to fire a brief set of pulses at a high enough voltage to strike a good tube within its range.

When it comes to tube failure the starter doesn't do anything if either electrode is open circuit. If the electrodes are both intact, when switched on it will do it's preheat-and-pulse sequence, and if the tube fails to strike then it won't repeat until the power is turned back off and on again. So all that happens is a dead tube will either do nothing or flash once when turned on and then stay off.

Watch this space... video of pulse starter coming soon.

Yeah It is similar to our current programmed rapid start electronic ballast, they basically glow the ends first, then powers it on instantly........I have a few of those ballasts, I will make a video of it as soon as I can............

My rapid start Motorola T8 ballasts actually act like programmed start, with electrode preheat and then light.  The beauty of these ballasts is no EOL and the fact that bad lamps will still run and rectify.  Only bad part is the noise the ballast makes with a bad lamp.

rapid start Motorola T8 ballasts.....   The beauty of these ballasts is no EOL and the fact that bad lamps will still run and rectify.  Only bad part is the noise the ballast makes with a bad lamp.

The PulseStarter sometimes do this too... EOL tube strikes and sits there buzzing with one end solid black. Eventually it goes out completely.

I recently came across a circline fixture that had a standard preheat ballast and electronic starter in place of a glowtube.  I was able to take the electronic starter out and fit it inside a standard starter can and now have an electronic starter that works on all my preheat fixtures from 4w-20w lamps.  With an EOL lamp that has intact electrodes, it will start and sometimes pulsate the lamp then the starter stops trying and the lamp is left rectifying.  I would like to find more of these little circuits and make more electronic starters!