18W 2 foot Florescent tube how long should they last.

[ericmark]

The florescent tube lighting my stairs and landing has failed. I bought the unit from a radio rally second hand in 1990 and modified it by adding a HF battery backed ballast so stairs are lit in a power cut. Used like every stairs light every day and often left on for long periods. So over the 20 years likely that tube has been on for at least 6 hours a day. So nearly double the 20000 hours Sylvania claim for the tubes. And as I say second hand in first place.

Yet the Sylvania Mini Lynx Ball CFL SES 9W used in living room have already had two failures and only been up for two years.

The kitchen also seems to need the tubes replacing after just 18 months to 2 years so I wonder if it is worth the extra money to convert them also to HF?

My son tells me how he has to replace HF ballasts on a regular basis so I am undecided as to if worth all the effort to change from induction to HF ballasts. Of course I know theory but wonder if in practice it's worth the effort to move over to HF.

Theory says the 18W tube should last 20 times longer than the old 60W tungsten bulb how ever before changing it seemed I was replacing the bulb every week.

Maybe my memory playing tricks but caravan with 8W tubes seemed to need them changing once a year (lived in van) so how long do people find tubes last for on average?

 

[JohnW2]

The florescent tube lighting my stairs and landing has failed. I bought the unit from a radio rally second hand in 1990 and modified it by adding a HF battery backed ballast so stairs are lit in a power cut. Used like every stairs light every day and often left on for long periods. So over the 20 years likely that tube has been on for at least 6 hours a day. So nearly double the 20000 hours Sylvania claim for the tubes. And as I say second hand in first place.

I've had a couple of such tubes in use for 25 years, installed when I first moved in to my present home. Although they get less use than you mention, their are probably well beyond their theoretical life.

As often discussed, the number of 'switch ons' is probably more important than the total number of hours of operation. A link provided by Alarm in a recent thread suggested that tubes were likley to die, on average, after about 6,667 switch-ons. If your stairs lights are switched on/off once per day, after 20 years you would be up to about 7,300 switch-ons - hence roughly in the ball park of that 'average life expectancy'.

Kind Regards,John.

 

[Stoday]

Depends on the ballast.

If the tube's cathodes are allowed a second or so to heat up before the arc is struck, the tube will have a full life. If the arc is struck with cold cathodes, they will get stripped and life will be short.

Some HF ballasts will preheat the cathodes, others will not. Generally the smaller tubes get the rough treatment.