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Topic Title: "Exploding" fluorescent tubes
Topic Summary: What happened here?
Created On: 30 July 2013 08:53 PM
Status: Post and Reply
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 30 July 2013 08:53 PM
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Grumpy

Posts: 360
Joined: 09 January 2009

Called out, twin vapour proof 5' flourescents had "exploded" and fortunately all the debris was collected in the cover. Got there, no exaggeration. Now, I have to confess that the flourescent lighting section of 2361 didn't capture my imagination . . . Took fitting off and what I might imagine to be a condenser had completely burnt out. I would be grateful if one of you more learned folk could explain what happened. Thanks.
 30 July 2013 09:13 PM
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michaelbrett

Posts: 920
Joined: 28 December 2005

Sounds like the capacitor failed short circuit. Not an uncommon fault. If it was connected across the supply, it was for power factor correction.

Regards

Mike
 30 July 2013 11:57 PM
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potential

Posts: 1239
Joined: 01 February 2007

I suspect the two fluorescents worked on the split phase principle where there are two ballasts/chokes and a capacitor in series with one of them.
One choke supplies one tube and the capacitor and choke the other.
The two circuits together give a good power factor and also eliminates the stroboscopic effect.
If the capacitor shorted out, the lamp would be overdriven and could explode perhaps destroying the other.
I recall that happened in a new installation many years ago and, since it was high up in a church hall and it happened not once but twice, I vowed never to install that type again.
 31 July 2013 07:48 PM
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Grumpy

Posts: 360
Joined: 09 January 2009

Originally posted by: potential

I suspect the two fluorescents worked on the split phase principle where there are two ballasts/chokes and a capacitor in series with one of them.

One choke supplies one tube and the capacitor and choke the other.

The two circuits together give a good power factor and also eliminates the stroboscopic effect.

If the capacitor shorted out, the lamp would be overdriven and could explode perhaps destroying the other.

I recall that happened in a new installation many years ago and, since it was high up in a church hall and it happened not once but twice, I vowed never to install that type again.


That's interesting, how do you recognise this type Potential?
 31 July 2013 07:57 PM
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perspicacious

Posts: 7032
Joined: 18 April 2006

"how do you recognise this type"

Generally by looking at the circuit diagram "screen" printed on the control gear.....

Regards

BOD
 31 July 2013 10:09 PM
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potential

Posts: 1239
Joined: 01 February 2007

Originally posted by: perspicacious

"how do you recognise this type"
Generally by looking at the circuit diagram "screen" printed on the control gear.....
Regards
BOD

Yes or by examining the actual wiring.
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