Neon lights exploding

Did it actually explode, or just burn up ? The black marks tend to suggest burning over a period of time. Insulation failure and subsequent tracking and arcing could easily start and sustain a fire, consuming the plastic etc.

A neon tube can't explode, there is allmost nothing in it.

Water damage? Started an external Arc behind the Letter and arc continued until a fuse blew or transformer failed ? Looks like Water was running down wall and soaked at least five of the letters ?

Yukio YANO

some clarification needed, ~3.5 was on the primary side.

after reading some more on the net, it seems like the most possible answer is either under or overloading the transformer. 80% load on the transformer seems to be the acceptable load. anything outside the range causes either the insullation to break down, or overheating and burnout. As of right now I have not seen the problem first hand, I have only been forwarded the images. i just wanted to educate myself on the possible causes and things to look for before i go on the site and see the problem myself. fyi, the problem occured on multiple installations, where the only common thing was the equipment supplier. since the supplier is now out of business ( wonder why...) my best guess is that the design was not properly sized, and one of the beforementioned conditions occured.

--- I doubt it. AIUI, neon sign transformers are designed to work into either an open or a short circuit, or anything in between. The loading on the transformer is based on the how much current needs to be put through the neon tubing and, the transformer is chosen depending on the length and diameter of the tubing and whether mercury is used with the fill gas.

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-- John Fields Professional Circuit Designer

How can Neon explode? It's an innert gas....

at low pressure (partial vacuum)

hmm, what if one of the end insulators filled up with water and then the tube sprung a leak at the electrode. water would get sucked into the tube,

could water in there and get electrolized to hydrogen and oxygen, and then get ignited and explode?

Nah, the increase in pressure would probably stop the current from flowing.

hmm, maybe the glass blower didn't anneal the glass correclty. I think that could cause it to shatter suddenly.

Bye. Jasen