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Fluorescent bulb questions ? Answered


Short question but sorry,  I cannot seem to shorten it; the actual question is in the last two lines .

My friend's outside light stopped working; Earlier today I was asked to replace the two bulbs; they had stopped working and seemed slightly brown on the ceramic part.

They are four pin fluorescents; I have not used these type before.

I went to Screwfix and their catalogue showed two bulbs that looked identical to the original but one model said for electronic ballast only and one type said for magnetic ballast only; the shop staff did not know what a ballast was and could not advise me, when looking at the original, which type to buy.

I went to Toolstation , no such distinction was made in their catalogue; I asked the guy about the ballast suitability; he did not know what a ballast was; I bought the one that seemed the closest in name.

I have never has to think about ballast types before buying a bulb before; but after buying the bulbs I found a sticker on the lamp saying -electronic ballast.

I stuck the first bulb in, it did not light.
I put the bulb, instead, into the next socket; it lit and stayed lit.
I put the remaining bulb in the first socket and both bulbs stopped working; whatever combination that I tried.

The original bulb was an Osram Dulux D/E 26w/840

The  new bulb is a 

sylvania lynx-de superia 26w 840  G24q-3

Technical Details
Brand Sylvania
Item Weight 9 g
Product Dimensions 16.6 x 3.6 x 3.6 cm
Item model number 25927
Part Number 0025927
Colour Cool White
Shape Stick
Maximum Compatible Wattage 26 watts
Voltage 240 volts
Specific Uses General purpose
Batteries Included? No
Type of Bulb Compact Fluorescent Light (CFL)
Cap Type G24q
EU Energy Efficiency Label A
Luminous Flux 1800 lumen
Wattage 26 watts
Wattage 26 watts
Bulb Features Low energy plug-in compact lamp
Colour Temperature 4000 Kelvin
Colour Rendering Index (CRI) 85
Average Life 10000 hours
Average Life 15000 hours
Bulb Length 167 millimetres
Warm Up Time 30 seconds
Lumen Maintenance Factor at the End of Life 95

I still do not know if it was the correct bulb or not but . . .
Here are the questions:

Are some bulbs suitable for both types of ballast ?

What happens if you put the wrong type in; does it just not work; or does it blow the bulb; or/and does it damage the lamp?

Thank you


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Jack A Lopez
Jack A Lopez

Best Answer 5 years ago

I think it is possible to discover what kind of ballast this lamp uses, by digging deeper, I mean, by taking apart your friend's outdoor light fixture and removing the ballast also.

A magnetic ballast resembles a transformer. Essentially it is a big lump of laminated steel, with windings wrapped onto it.

In contrast, an electronic ballast, looks like a circuit board, populated with a whole bunch of different components on it.

Anyway, that would tell you what kind of ballast you've got (magnetic or electronic).

Also I am guessing that once the ballast has been removed, there is a connection to mains power right under that. Thus there exists the possibility to install some other light emitting device; e.g. a new CFL with its own ballast, or maybe even a new LED based lamp.

I mean, it may come to that, if you can't find a bulb that matches the existing ballast.

BTW, the picture you upped looks a lot like what is called a "CFL with non-integrated ballast", and the only reason I know that is because there is a picture that looks almost just like it, in this Wikipedia article:



Answer 5 years ago

Hello Jack A Lopez,

Thank you for the comprehensive answer.

The preamble to my question was rambling and in it I mentioned somewhere that I had discovered that the lamp had an electronic ballast, but your explanation was still enlightening.

Yes, it is a CFL bulb.

My main question ,though if you are still game,was - if I put a bulb designed for a magnetic ballast into a lamp with an electric ballast will it :

1)Simply not work

2) Not work and blow the bulbs


3) Actually harm the lamp.

Many thanks

Jack A Lopez
Jack A Lopez

Answer 5 years ago

I'm not at all sure what would happen, but (1), (2) and (3) seem like believable possibilities.

Although, I think I heard, or read, somewhere, that ballasts are difficult to break. For example the output of the ballast can have a short across it, and that's one of the conditions it is made to withstand. I think.

I thin the fluorescent tubes are probably pretty tough also, but still, I don't know what will happen.

If anything catches on fire, or makes any bad smelling smoke, that's usually a bad sign.



5 years ago

just to amplify the answer below, which i totally agree with:

A ballast is used to limit the flow of current through a device, often a florescent tube.

Until the tube has struck and created it's plasma the resistance will be very low and this will allow a lot of current to flow. The ballast limits this to avoid tripping the breaker every time you turn the light on. They can as said below be a large heavy coil or an electronic cct board. because of the cost electronic ballasts are most common now.

The starter on the other hand creates a higher voltage briefly to get the plasma going.


Answer 5 years ago

Dear Rick Harris,

I was in a hurry when I wrote the question,but your answer lead me to reading a bit more about the subject..

It is a CFL bulb.

My main question, though if you are still game, was - if I put a bulb designed for a magnetic ballast into a lamp with an electric ballast will it :

1)Simply not work

2) Not work and blow the bulbs


3) Actually harm the lamp.

Many thanks

Apologies, The Instructables editor is putting spaces in weird places.