Circular fluorescent tubes

[weirdgeordie]

Hi all,

My apologies if this is the wrong place to be asking, but I've got a 300mm circular fluorescent tube fitting in my bathroom and the bulb recently went south.

I'm having real trouble finding an exact match of the specs listed on the bulb. It's made by Crompton, 32w/830 T10. 4 pin.

Now my question is, I can find tons of T9 circular bulbs, but T10 circular bulbs seem very uncommon, at least here in the UK, as I cannot find any on any online shop, eBay, amazon.co.uk, or anywhere else with any listed.

If I buy a T9 circular bulb, will that work? Or are the pins arranged differently on T10 circular bulbs?

I would be very grateful indeed as I'm pulling my hair out on this one. Not to mention stubbing my toes in the night!

Thanks in advance!

James.
 

[Nusa]

(edit) Quick wiki reads tells me:

The T number apparently refers to the size of the tube, not the diameter of the circle. The difference between T9 and T10 is pretty minor, and probably compatible. I'd make sure the other physical factors match (circle diameter, connector) and try one.

[weirdgeordie]

Oh, sorry, my apologies about not mentioning the fixture.

The fixture is on the ceiling, has metal arms in a ring with a shallow indent that cradle the bulb. They don't hold it tightly, the bulb just rests on them, so the tube doesn't have to be the exact same size. In the middle are the electronics, (starter etc.). A defuser/cover clips over the top, again loosely.

I'd take a picture of it with my phone for you, but my phone's battery is bulging, and I just don't trust a bulging lithium ion battery!

[Nusa]

Edited my reply above as you wrote yours.

[james_s]

If the connector fits then it will probably work just fine. The T number is indeed the diameter of the tube in 8ths of an inch. Why they use that oddball measurement I don't know but it has always been that way. The 830 means 80+ color rendering index ant 3000k color temperature, so slightly less yellow than 2700k incandescent.

[weirdgeordie]

I've taken measurements and the old bulb's pins match a G10q fitting measurements exactly. So it looks like it's a go! I thought I was going to have to order from a specialist supplier or something for a while there!

Thanks for your responses.

James.

[james_s]

I've been into lighting for as long as I can recall, but I've been a bit out of the loop lately. I don't remember ever hearing of T9 tubes so I suspect they've figured out they can save a bit of glass and phosphor by making the tube diameter a hair smaller figuring few people will notice.

Unlike the trend of the magically shrinking cartons of ice cream and candy bars at least a slightly smaller tube diameter is unlikely to have any real negative impact on the consumer.

[steverino]

I've never been a fan of fluorescent lighting in the home.  I just replaced a similar light fixture in a bathroom to a led fixture.  No going back.

[james_s]

LED really is nice, at least the good ones are. No warmup time, marginally higher efficiency, 90+ CRI is becoming readily available. I do still like the look of those circular fluorescents though, they have a nice vintage charm and are ok for utility areas.

[IanMacdonald]

I've never been a fan of fluorescent lighting in the home.  I just replaced a similar light fixture in a bathroom to a led fixture.  No going back.

The ones that use a HF inverter are vastly better than the iron core choke type, which flicker noticeably. For some unknown reason the ones stocked by wholesalers are always the old fashioned type though.

LEDs can also suffer from flicker if the driver is not properly smoothed. Though the issue I find with many LEDs is that they are too tightly focused. All you get is a circle of light on the floor. The COB type are better in this respect, giving a more even light.

[weirdgeordie]

Unfortunately, as I don't own the property, I can't change the light fitting, so it'll have to be a straight bulb replacement, otherwise I would have preferred LED.

I think I actually saw an LED designed with circuitry as a drop in replacement for a real fluorescent tube - I can't imagine that it would be very efficient.

[paulca]

Are these any use?
https://www.amazon.co.uk/Circular-T9-20-White-6500%C2%BAK-Brightness/dp/B01N7ZDUDD/ref=sr_1_1?ie=UTF8&qid=1513183653&sr=8-1&keywords=T9+LED+circular

[james_s]

In the US magnetic ballasts were banned a while back so all the new ones you can buy now are HF electronic. There is a downside to that though, the old iron core magnetic ballasts often lasted decades and were reasonably immune to power surges and such while most of the electronic ballasts seem to be less robust.

In the UK and other 240V countries the standard fluorescent ballast is nothing more than an inductor so an LED retrofit may actually be fairly efficient. Nothing really wrong with fluorescent though, if you don't mind the light I would just stick with it.

[weirdgeordie]

Are these any use?
https://www.amazon.co.uk/Circular-T9-20-White-6500%C2%BAK-Brightness/dp/B01N7ZDUDD/ref=sr_1_1?ie=UTF8&qid=1513183653&sr=8-1&keywords=T9+LED+circular

Yep, indeed, that's what I need, just a bit more wattage equivalence and a warmer white. Thanks 

[weirdgeordie]

Hi guys,

I'd be really grateful if you could help me quickly on one last question? I apologise in advance if it's a bit of a noob question.

The new tube arrived     I went for a straight replacement and for a fluorescent tube, rather than an drop in LED replacement. The tube was A rated for energy so it seemed like I wouldn't save on energy by going LED.

Anyhow, the tube works  - However it's slow to start and has a slight pulsating flicker when it strikes. Does this point towards the starter or the ballast that needs replacing? 

Many thanks in advance,

James.

[weirdgeordie]

Never mind, sorry to bother everyone, after a few failed strikes the first few times switching it on, the tube strikes first try every time now. I guess it was just the mercury vaporising. 

So all working, all good.

Thanks again for all your help everyone,

James.

[paulca]

mercury vaporising

That would be a good album title.

[drussell]

Unfortunately, as I don't own the property, I can't change the light fitting, so it'll have to be a straight bulb replacement, otherwise I would have preferred LED.

Interesting.  My lease papers specifically say I am responsible for light fixtures and their bulbs.  I can change them at will.  (Indeed, I have done so, on a couple of them..)  Even somewhere where they're supposed to be responsible for them, you could always ask if you can change one out, especially if you're supplying the fixture. 

Even in an electricity-included rental where they want people using efficient light sources, you would think they would go for it if your new fixture is more efficient than the old. 

[weirdgeordie]

Unfortunately, as I don't own the property, I can't change the light fitting, so it'll have to be a straight bulb replacement, otherwise I would have preferred LED.

Interesting.  My lease papers specifically say I am responsible for light fixtures and their bulbs.  I can change them at will.  (Indeed, I have done so, on a couple of them..)  Even somewhere where they're supposed to be responsible for them, you could always ask if you can change one out, especially if you're supplying the fixture. 

Even in an electricity-included rental where they want people using efficient light sources, you would think they would go for it if your new fixture is more efficient than the old. 

There is actually a clause in the tenancy agreement that no electrical work to be undertaken without permission. It's a housing association house, so no doubt they have a lot more red tape to deal with when it comes to health and safety. There's even a huge sticker on the back of a kitchen cupboard door that says "No electrical work to be undertaken without prior permission" - You have to actually apply in writing, hire an approved electrician, it's British bureaucracy at it's best.  It's actually ambiguous if that includes bulbs!   

[james_s]

Certainly I would be annoyed to say the least if I owned a rental property and tenants took it upon themselves to change out built in light fixtures. I've cleaned up some really botched work done by people who thought they knew what they were doing. If they wanted a light fixture changed and were willing to pay for the new one I'd install it myself.