How were these still working?

[GBDamo]

Removed and replaced 6 8ft fluorescent fittings today and all were similar to the bellow yet all were still working, how?

 

[buzzlightyear]

?

 

[GBDamo]

?

Oh do elaborate, don't mind being laughed at, at all, but wouldn't mind knowing why.?

 

[loz2754]

The capacitors have obviously burned out open circuit. As they are only power factor correction capacitors the lights would still work.

 

[pc1966]

As above, fluorescent lights have inductive ballast to regulate the current in the discharge once they light up (after the starter has pre-heated the ends and opened), so they usually have the parallel correction capacitor to compensate for that and get the overall power factor closer to unity.

I am more surprised it got in to that state without either an obvious fire or tripping breakers, etc!

 

[GBDamo]

As above, fluorescent lights have inductive ballast to regulate the current in the discharge once they light up (after the starter has pre-heated the ends and opened), so they usually have the parallel correction capacitor to compensate for that and get the overall power factor closer to unity.

I am more surprised it got in to that state without either an obvious fire or tripping breakers, etc!

Now imagine my surprise that six were in the same state, and working, with no ill effects.

 

[James]

I bet the breaker did trip, but after several resets, the faulty cap blew fault clear.

 

[Lucien Nunes]

Metallised polypropylene capacitors of this type can burn out progressively without ever taking a large enough current to trip the breaker. A transient punctures the film, the arc spreads until the film melts, but at the same time destroys the metallisation so that it's only arcing round the edges as they advance through the element. X- and Y-capacitors have a more controlled behaviour where the arc ablates the metallisation leaving the film intact,, the so-called 'self healing' process. They don't go into meltdown, but if subjected to frequent transients, gradually lose capacitance until they are inert blocks of plastic.