Flossy lights - rewire

[slider45]

I have a twin fluorescent fitting wired in but I'd like to control each tube with a different switch.

(actually I have a few of these double fittings - and I want one switch to control say the left hand tubes and another switch to control the right hand tubes).

Looking inside we have something along these lines:

My question is - it seems like the 'capacitor' is only fitted inline with one tube. Why is this?

Thanks.

 

[Lectrician]

The capacitor will be across L and N of the supply, not in series with one lamp cct.

 

[slider45]

The capacitor will be across L and N of the supply, not in series with one lamp cct.

Just been out to check - it is as illustrated above! Its been working for at least 5 years like this!
Perhaps its more than just a capacitor.? It does have a farad rating though.

Its a thorn unit.

 

[Adam_151]

Whats the rating?

Plug it into (2.pi.F.C)^(-1) for a quick sanity check of what sort of impediance it would present, but it does seem most irregular!

EDIT: F went walkabout

 

[ricicle]

That'll be a lead-lag fitting for preventing the stroboscopic effect...

 

[slider45]

Whats the rating?

Plug it into (2.pi.C)^(-1) for a quick sanity check of what sort of impediance it would present, but it does seem most irregular!

Its a Bosch 0 670 323 227 ............ 5uf +/- 5% .......... MPF

Anti strobe? I'd have thought the fitting predates that kind of hi-tech trickery!

Question remains - why only on one? Safe to wire separately?

 

[ricicle]

Anti strobe? I'd have thought the fitting predates that kind of hi-tech trickery!

That method has been around for years.

 

[Spark123]

A tube will flicker at 100 times per second as the voltage passes through zero. This may cause a moving piece of machinery may appear stationary, rather like using a timing gun on a car.
The reason for putting the capacitor in there is so one tube is slightly out of time with the other hence they don't both pass zero at the same time.
Is there another capacitor in there too? Are they above moving machinery?

 

[Adam_151]

Question remains - why only on one? Safe to wire separately?

If it was on both then the effect would be null... the purpose is to push one out of phase in relation with the other... think of a capacitor start induction motor

 

[slider45]

A tube will flicker at 100 times per second as the voltage passes through zero. This may cause a moving piece of machinery may appear stationary, rather like using a timing gun on a car.
The reason for putting the capacitor in there is so one tube is slightly out of time with the other hence they don't both pass zero at the same time.
Is there another capacitor in there too? Are they above moving machinery?

Aah - thanks for the explaination. There is just one cap so lead lag sounds right.
Yup originally fitted in a workshop so it all ties in. Thanks for your help one & all.

 

[Lectrician]

The capacitor will be across L and N of the supply, not in series with one lamp cct.

Just been out to check - it is as illustrated above! Its been working for at least 5 years like this!
Perhaps its more than just a capacitor.? It does have a farad rating though.

Its a thorn unit.

Oh right, in that case you are missing a capacitor across the mains, and the one that is there is to cause one tube to lead the other to counteract stroboscopic effect....common in machine shops etc....