This kitchen light has been in place for several years an all seems to be working fine but when this unit is switched on it makes a buzzing noise. It is not connected to a dimmer switch. Any ideas please ? Is it the starter ??
Cheap domestic florescent fitting have a started and choke the latter gives both the high strike voltage on starting and limits current on run and is basically a big coil of wire on a lamented iron core it is these lamentations which vibrate and make the noise. There is nothing wrong with the lamp it is normal but one choke may have slightly tighter or slacker lamentations to another giving more or less noise.
There is a more expensive system that uses a switch mode module these work on high frequency and are called HF units they use less power plus less dependent on correct voltage and give out more light plus make the tubes last 5 times as long. They are used a lot in industry some times they do make a very high pitched singing noise but in the main make no sound. They also do not produce the stroboscopic effect so are safer where machinery is used. Some can also be dimmed.
When you see the price I think you will stick to cheap ones. But since hum is not considered as a fault you can't return one to supplier with that fault.
All best Eric
PS I tried B&Q for one didn't even know they existed you would need to go to good electrical wholesaler.
If it is a starter type Fitting then the choke sounds worn out.
If it is twin it may have two units.
Or it may just be insecure and vibrating
You can buy a new internal choke but it is dearer than the fitting, and only worth doing on a fancy expensive fitting that you do not want to totally replace or if it has an expensive diffuser.
Or you can just buy a cheap whole fitting same size and just use the choke out of it
If possible change the whole fitting, but could work out dearer as the old diffuser (if fitted) possibly wont fit and will be more expense.
High frequency are now becoming the norm now
something to do with the interferance and losses given off, switchstart chokes have been outlawed by the EEC.
Modern chokes have been redesigned to get round this until we join the EEC
Due to no demand for them apart from uk.
Manufacturers are selling more H/f and the price is coming down.
As eric said H/F are better in many ways.
And I think they are worth the extra cost.
Cheaper to run, better light and less heat,more efficient and no annoying flashing at switch on.
Combine that with a Triphosphor gas tube (Type 8 gas) 835 white.
And will last many years with no further maintenance