70w flourescet tubes won't light

[DIYspanner]

I have old capacitor start fluorescent lights in my garage.

I bought some new 70w tubes but when fitted, the ends slowly start to glow but won't light up.

Can I presume these old lights are won't work with modern tubes?

 

[flameport]

If they are SRS fittings, the outside of the tube needs to be in close contact with the metal body of the light fitting, so the narrower T8 tubes won't work, but the older T12 will.

 

[DIYspanner]

They're quite old the ones I have, they have starters.

 

[333rocky333]

6ft tubes on a magnetic choke are the most temperamental tube, ensure the starter actually has 70W on it .
If its the really old 4 wire ballast then it will likely only work with the old T12 version 6ft tube
Not sure what you mean by capaciter start, if the cap is in series with the lampholder, the lamp will likely still work by removal and linking it out

 

[DIYspanner]

The tubes I bought are the thinner T8. The old ones are 1.5" (T12)

I'll take the tubes back and get T12 tubes instead and perhaps new starters.

I always thought the starters you plug in and twist had a capacitor in them - hence capacitor start?

Thanks for posting folks.

 

[333rocky333]

There is no Starting Cap in the starter, ok maybe a small Cap in there for other reasons
More a type of switch, hence "switch start"
The only caps used are either in the main casing across the supply for power facter correction or
In series with the lampholder, also inside the main casing of a twin fitting for anti strobing or
In series with the lampholder also inside the main casing for a bit of start boost, but usually reserved for 8ft fittings
Personally id keep your thin tubes and try 70w starters 90% of the time they will work

 

[Echo the husky]

If the end glows but doesn't start it will likely be a faulty starter, the starters do have a capacitor inside but this is mostly for interference suppression. Make sure the starter is suitable for 70W tubes such as an FS125. Most T12 fittings will work with a T8 tube, but there are some that wont. You will probably struggle to find T12 tubes now as they were banned some years back, a shame as they had a very very long working life.

edited to remove incorrect information.

 

[333rocky333]

If the end glows but doesn't start it will likely be a faulty starter, the starters do have a capacitor inside but this is mostly for interference suppression. Make sure the starter is suitable for 70W tubes such as an FS125 or ST111. Most T12 fittings will work with a T8 tube, but there are some that wont. You will probably struggle to find T12 tubes now as they were banned some years back, a shame as they had a very very long working life.

Not sure an St111 is suitable
http://www.osram.com.au/osram_au/pr...rs-for-single-operation-at-230-v-ac/index.jsp

Technical dataExpand
Electrical data
Nominal voltage 220…240 V
Nominal wattage 65.00 W
Mains frequency 50…60 Hz
Dimensions & weight
Length 40.3 mm
Additional product data
Product remark Not suitable for L 70 W
Graphics and application imagesExpand
DownloadsExpand
Packaging informationExpand
Country-specific information

 

[Echo the husky]

Some of Osrams information said it was, other information as a bit vague...

 

[333rocky333]

Some of Osrams information said it was, other information as a bit vague...

We use a lot of 6ft in shopfitting so recalls are a pain
Personally i find unless it says 70w on the canister i avoid
there are lots of variations that might work but I find its not worth chancing
4-65w & 80w seems to be a popular starter , but note they avoid saying its suitable for 70watt, so i would avoid

 

[Echo the husky]

Yes you are right, because the 80W rating will be for 5' T12 tubes. I've corrected my post.

 

[ban-all-sheds]

If they are SRS fittings, the outside of the tube needs to be in close contact with the metal body of the light fitting, so the narrower T8 tubes won't work, but the older T12 will.

And as a total hijack (not posted about this as it's a low priority) - in my loft I have 3 x twin-tube (short) fittings. They actually came out of old lightboxes, and are 450mm max tubes. Switch start, and when switched on, two of the fittings do the usual short-flicker-and-on. One of them does SFA. No flickering, no abortive attempts to start, no phantom glow at the ends of the tubes, nada. As if it had no power at all.

After several minutes (5? 10? Not an exaggeration, but I've never timed it properly) it just suddenly comes on with no drama.

 

[DIYspanner]

Well it seems I was mistaken in thinking the lights had starters, they don't as the lid off photo shows -

They are double lamp lights but I only have one tube in each.

Each lamp circuit has what looks like a tube shape capacitor and two white boxes.

The electric wholesaler doesn't have T12 lamps. The local DIY store has a few left at £11 each.

 

[flameport]

SRS or semi resonant start, which had no starters and instead had a capacitor and a transformer arrangement. Also sold as 'instant start' and similar names.

The design relied on having the tube next to the earthed metal case, or in a few types the tube itself had a metal strip along one side, http://www.lamptech.co.uk/Spec Sheets/D FL Mazda MCFA20.htm

Smaller diameter tubes rarely work in such fittings.

 

[ban-all-sheds]

Every day is a school day.