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problem floresent lighting

hi guys,today I was in a old people home, I was there to replace two florescent light fittings that were going off and on and flickering.I replaced the two fittings but now the new fittings are doing the exact same thing. I tested to see if there was the proper voltage to the two fittings and this is ok, I also checked the connections and they are ok as well.I have to have these lights fixed for tomorrow,oh I for got to mention that these two lights are on a circuit along with 15 28w 2d fittings and the board also says ,'telephone' but I cant find this on the circuit,any help would be most welcome.
 
As the others have said Check the starters and lamps especially the sizes ,how often you find incorrect value starters in light fitting ,are any other lights doing this , check the supply voltage and do a Ze test at the board especially if its a three phase installation , there is a possibility that the switching on and off and flickering is caused my a supply fault but this would be apperent in other parts of the building but worth while checking
 
I once had a propblem similar to this, although certain lights refused to work dispite there being 230v at the fitting, i traced the cables all the way through the circuit and everything was as expected.
Turned out the neutral was picking up a voltage of around 50v somehow as it was through wired through a flourecsent tube fitting, i re-routed the cable and all the lights worked perfectly!
 
What size are the fittings?

For 6 or 8-Foot ones you need a different starter, marked for 70-125W tubes. Sometimes called an FS-125.
Generally everything else will work with the standard type, sometimes called FS-U.
For two 2-footers on a single ballast, you need the specific series type (110V) starter, or sometimes the lamps will refuse to do anything.

Why?

The starters have a gas filling which passes current at a set voltage.
This current causes it's bimetal elements to heat and bend, shorting together.
Then there is no voltage across the starter, so the bimetal elements cool.
As the contacts part, the energy storesd in the inductive circuit is released, creating a large voltage across the lamp.
Hopefully the arc strikes in the fluorescent lamp. If not, the process repeats.

The normal running voltage of the lamp is lower than the voltage that the starter conducts at, so the starter passes no current.

However, if you put an FS-U starter in a 6Ft fitting, the voltages are very similar, so the starter will occasionally conduct, extinguishing the lamp for a few seconds.

Sometimes, the starters have the wrong guts in them!
Generally, FS-U glow blue, and FS-125 glow pink.

Simon.
 
Thanks guy's for all your reply's. I got to the bottem of it today. When put my meter on the circuit today I was getting between 210 and 217 v so i took down the two fittings and put up two electronic fittings. I kept an eye on them for about half an hour and the flickering and going off and on has stopped .
 

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