Change 2D ballast & tube - 28W to 38W

[garmcqui]

HI, I'd like to change the ballast and tube in my 2D bathroom light fitting from a 28W one to a 38W, to get more light.

I've seen ballasts on Amazon and I can get the bulbs anywhere. However, there are two versions of the ballast, one if rated 0.17A and the other 0.28A:

http://www.amazon.co.uk/Electronic-..._sbs_kh_1?ie=UTF8&refRID=02DN98PMQADAJGE85KFX

http://www.amazon.co.uk/Wired-Fluor...sbs_diy_8?ie=UTF8&refRID=0VEQ52D58M9FZ90AQJQK

Now by my maths, 0.17A x 230v = 39.1W ,so why do they offer the higher rated one if it's a 38W ballast?

Also, if there are better 38W ballasts, please advise.

Thanks

 

[flameport]

The 0.28A model has an additional figure on the product as 0.65
The 0.17A model shows 0.95
Presumably this is power factor, hence the higher current on the 0.65 one.

Both of those items are shipped from Hong Kong and will take 3-4 weeks to arrive.

Better ballasts are available, however they usually require a separate lamp holder and they cost a lot more. One example: http://www.meteorelectrical.com/ballast-hf-1-38w-2d.html

 

[ban-all-sheds]

Both of those items are shipped from Hong Kong and will take 3-4 weeks to arrive

But possibly less time to fail.

 

[garmcqui]

thanks for that... don't like the sound of coming from HK.

For that Ballast you linked to, can I use the existing 28W lamp holder? Or could you please point me towards a suitable one?

Thanks,

Gareth

 

[ericmark]

There are two ways to control any florescent lamp one is using a coil of wire wrapped around the iron core called a ballast which gives the high voltage required to strike the tube and then limits the power used by the tube. The control often also contains a starter and these can be bi-metal strip or electronic. When both are in the same package then whole item can be called electronic.

The second turns AC to DC and then back to AC at a high frequency it's called a HF ballast using the old name but it has a whole list of advantages over the old type.

1) No power factor correction is required.
2) The lamp gives out more light.
3) The lamps last longer.
4) The voltage has some latitude often 200 - 240 volt.

With the old type using a 220 volt model with 230 volt uses a lot of extra power and use a 230 volt model with 220 volts it will fail to start. From the cost even though it says electronic I would guess this refers to the built in started and they are not HF fitting so instead of using 0.17 amp it will use far more due to both power factor and being wrong voltage which means they will also fail sooner as they will be running hot and use more like 50W than 38W.

At first it will seem far brighter but within the year it will likely be dimmer than a 28 watt HF unit and you will need to swap lamps every 18 months rather than the 20 years you may get from using a proper HF ballast.

I still use the old tubes in my kitchen and swap tubes every 18 months but at top of stairs have HF ballast and last year fitted my first replacement tube after fitting it in 1994.

 

[333rocky333]

The lampholders are universal for both 38 and 28, those foreign ballasts are not common in the uk, the lamp sits too close to the ballast in my opinion, and may even not fit in your light, your fitting most likely has the ballast behind the main panel
Personally your better buying a 38 watt CE certified complete fitting

Not sure you would notice any difference maybe just an 840 28watt lamp may be better

 

[winston1]

The current ratings are the current through the lamp not the current taken from the supply. The voltage across the lamp is less than mains voltage. Using the current times this unknown voltage should give the correct power, assuming the lamp PF is unity.

But those units are 220 volt units for Hong Kong. Using them on our 240 volt supply would not be wise.

 

[RF Lighting]

The current ratings are the current through the lamp not the current taken from the supply. The voltage across the lamp is less than mains voltage. Using the current times this unknown voltage should give the correct power

I've missed your fact free nonsense posts

 

[winston1]

The current ratings are the current through the lamp not the current taken from the supply. The voltage across the lamp is less than mains voltage. Using the current times this unknown voltage should give the correct power

I've missed your fact free nonsense posts

What are you on about?

 

[RF Lighting]

Your posts which are free of facts and nothing more than amusing nonsense.

 

[winston1]

Your posts which are free of facts and nothing more than amusing nonsense.

You are entitled to your opinion. But if you think I have made a mistake say so. Don't just post insulting comments. I am always open to discussion.