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CamaLamaDD 10-19-2012 01:22 PM

Neon Sign Transformer Leaking a Substance

I have stumbled across a neon sign transformer (120v / 12/15KV, can't remember) that is leaking a very weird substance out the seams of the can. I have attached pictures.

It is a white, fluffy and powdery substance, looks a lot like snow. It has piled up on top of the transformer and also a little bit out of the side. The reason I looked up there was because the neon sign started flickering the day before.

I opened up the lid expecting to see it full of this stuff, but there was basically none at all on the front side of the transformer. It is encased with tar, so I have no idea what is behind the tar.

My journeyman electrician said it could be a capacitor, but likely the whole thing would have to be replaced if there is a part that is shot. I don't know the age of the transformer, but it's at least a few years old.

Just looking for some input on this.


(Sorry for iPhone quality. The burnt wire is from a previous short)
picture hosting

mpoulton 10-19-2012 03:51 PM

It's hard to tell from the pictures, but the "stuff" doesn't appear to actually be leaking out of the transformer, does it? It looks like it's accumulating on the surface. It looks suspiciously like the fluffy zinc compounds that can form on galvanized metal when it is subjected to some acids. Are you sure there hasn't been something leaking onto the transformer? Water leak? What's the deal with those conduits directly above the location of the weird stuff?

Also, I notice that the top secondary lead (high voltage wire) inside the transformer has insulation damage a few inches from the terminal. This looks like corona damage, maybe even arc damage from complete insulation breakdown. That's probably a result of the wire resting against the inside of the transformer's cover, creating a corona discharge. This heats the insulation, and it also produces ozone and nitric oxide which chemically attacks everything nearby. If there were a persistent corona problem inside the transformer and a small water leak onto the top of the transformer, the water and ozone/nitric oxide would form a really corrosive solution that could attack the galvanized metal case and cause the fluffy white stuff.

Anyway, you need to fix the insulation damage. That's probably why the sign is flickering, and it's a fire hazard.

mpoulton 10-19-2012 03:55 PM

Oh my. I just noticed something. On the drywall around the top left corner of the transformer, is the paper burned away? It certainly looks like it is, and the vein-like burn pattern is characteristic of high voltage arcing. Can you post more pictures clearly showing the whole installation? Definitely don't turn this back on until you get to the bottom of this.

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