I thought old school tungsten filament bulbs couldn't legally be sold any more?

High voltage on the mains can cause light bulbs to blow. In NZ the mains voltage is required to be 230V + OR - 5%. (approx 218 to 242 Volts).

A higher voltage is often noticed by a higher rate of light bulbs blowing. It may pay to check with the neighbors to see if they are having similar problems - this would be another clue.

Checking the mains voltage with a multi-meter will not necessarily show up the problem as the voltage will vary through out the day due to the varying loads on the network. You really need to use a recording instrument to check over a period of time.

It also pays to keep in mind that shades can be detrimental to lamp life as well. It is not uncommon for lamps to be limited to 60W when fitted into a lampshade. It would be worth seeing if a 60W bulb lasts as compared to the 100W bulbs.

I would try the 60W bulb before chasing around on voltage.

MikeAqua:

 

I thought old school tungsten filament bulbs couldn't legally be sold any more?

 

No, that was one of Aunty Hulun's policies that lost them the election

philips did make a 260v lamp for this exact problem of higher voltage and or voltage spikes, they no longer make these and have apparently been superseded by the philips eco classic halogen energy saver which philips claims that they can withstand the voltage spikes and or higher voltage

Interesting tips, thanks guys.

Re my hardware, the current dimmer is a 'PDL 624TWH Trailing Edge' on a 1-way circuit.

It was installed around July 2015. It replaced a troublesome Voltex CDM 250 dimmer.

Contributing factors (handily pointed out by Mathew and K, cheers) may be that our location is a small rural Southland town, and we do have a transformer across the street.

From now, I'll try and ensure that the dimmer is switched on from its minimal state, instead of the full setting from which it was previously switched off.

BTW, when this unit is running fully dimmed, the lamps are still glowing, possibly around the 25% output noted by timmmay.

May I, on the subject of blowing bulbs, ask a question.

I have bought a lot of "energy saver" bulbs. I am after around 60-100W equivalent brightness of the old tungsten ones. The unheard of brand ones from Mitre10 keeps blowing. I have replaced them with Philip/Panasonic ones - not sure if they last longer but they probably do. The lamp in the hallway has not had its bulb changed for 12 years! House voltage aside (I have no idea how to tell) - Are they the best brands? These things are not cheap! Goodness only knows why I bought the unknown brand ones.

I would consider LED but only if they are reliable and the same price as the Philip ones. 

And would mixing different bulbs on one light system (one switch, 3 lights) be ok in terms of preventing blowing bulbs? Buy lower output ones - last longer? The hallway lamp has very low output.

I suggest your next step is to buy the bulbs @sparkz25 recommended.

timmmay:

 

I suggest your next step is to buy the bulbs @sparkz25 recommended.

 

He says it's not made anymore

Oh ok. Then get a decent quality modern bulb, probably LED, like I suggested on page 1.

sbiddle:

 

When LED's are now as cheap as chips (I saw $3 the other day) there seriously is no reason to use a normal bulb.

 

 

 

Where/what brand?

joker97:

 

sbiddle:

 

When LED's are now as cheap as chips (I saw $3 the other day) there seriously is no reason to use a normal bulb.

 

 

Where/what brand?

 

Mitre 10, some made up brand so it is immaterial what it is, and they were all sold out when I went in there.

Just stick to real brands, $3 or $10 doesnt really make much difference if you have to buy the $3 one many times.

philips make a good one, have changed a few in my house and they seem to be really good, i would say panasonic is good too, in my opinion you pay for what you get, as i have seen many time the budget lamps are crap the glue always gives way and leaves the cap in the lamp holder, they never last long, i have always recommended spending a little bit more on a good quality lamp to customers

Is it bad to put different bulbs on a 3 bulb lamp?

@joker97 what kind of lamp?? 9 times out of 10 its ok, providing you stick to the maximum wattage stated on the lamp holder or on the base of the fitting should be a sticker or on the model tag name plate for example MAX WATTAGE LAMP 25 or something smiilar to that