I have a customer who has neon lighting around his business exterior. I was on his roof checking on another project with the manager up there with me. The manager started walking around his roof area while I was checking on the other project. He called me over to some flex that was feeding the transformers for the neon lights. It was making a buzzing sound. As I was checking it, my finger brushed up against the flex and I got a small tingle. I got my tester and checked to see if there was any voltage on the flex and found out there was around 85 to 90 volts from the flex to a piece of conduit right below it. The conduit actually had little white dots where the flex had been touching it, and also the conduit had a rusty area in the same area. Other parts of the conduit had no discoloration. I checked other parts of the flex around the roof and the voltage was not as high as it was where we heard the buzzing sound. Do these flex carry regular current carrying condutors to the tubes, or are there just electodes in them? I haven't worked much with neon lights, but I did tell him it needed to be checked out. That much voltage on the exterior of the flex could pose a shock problem, don't you think??? Thanks for the input..

Mate,
You want to be very careful testing a thing like this especially with test gear that is only "good" for 600 or 1000V.
Neon signs use a secondary side voltage (depending upon the size of the sign) of between 15 and 50kV.
The wires on these signs need to have the proper silicone insulated wires, you can't use ordinary wire at these voltages, especially if they are exposed to the weather.

I went to a place a few years back where people were getting shocks (not just a tingle) off the doors in a restaurant kitchen, I found that the neon sign on the roof had really dodgy wiring and was leaking to earth via the steel roof and framework, but not enough current to blow any protection gear.

My advice would be to tell the guy to get a proper sign guy to have a look at the install, it sounds like it needs some work.

Trumpy, thanks for the advise. That's what I'll do. No sense in getting in something way over my head. I'll stick to what I know:)