Neon Transformer

gebasgt

Can the secondary wires of a neon transformer that is mounted above a drop ceiling pass through the ceiling to the neon sign below? I'm not sure what type of cable they use for neon transformers. I'm thinking no but don't know what article.

mdshunk

The secondary is normally done with "GTO Cable".

gebasgt

Is that cable allowed to pass through the drop ceiling tiles?

WCSG

Not unprotected. Has to be in a conduit.

DaveTap

and if allowed... its usually better if its not metalic conduit.
Of course if the grid ceiling is used as an air return plenum... transformer and wiring have to be plenum rated.

goose134

I have only done one installation with neon, so I'm not an authority, but I do know that we installed the cables in aluminum rigid. I was told it was so the cables wouldn't induce on the raceway. I'm not sure if it was frequency problem or what. The frequency induction came up at Midway airport, where they had to install the feeds for the aircraft in aluminum because the source was running at 400 hertz and would have heated EMT or GRC. two cents

Sparky Joe

In an aircraft they used aluminum conduit because weight is everything.

I don't know why you'd use it for something on the ground. It's a non ferrous metal, but still succeptable to magnetic induction(any conductor is)

goose134

This was an install in the terminal for some kind of plug in FOR the airplanes. I don't know the details of what that might be ( perhaps a pilot out there could enlighten us). Anyways, think about what you said, magnetic induction. Aluminum rigid conduit is NOT magnetic. The conductors were copper, the raceway was aluminum. Sorry if I wasn't clear.

Sparky Joe

Are you talking about what's reffered to as a Fox Cart? The device that plugs into a 30 or 60 amp 480 outlet and provides 400Hz to the plane, the machines themselves are made of steel by the way, and cabling is SO.

You were very clear GOOSE, perhaps I wasn't clear in my sentence that read;
It's a non ferrous metal, but still succeptable to magnetic induction(any conductor is)

goose134

Sparky, I'll be honest with you, I wasn't that involved with that install. I was working side by side with these guys and was simply curious why they were running aluminum. As for the amperage, who knows? I know they were running 2 1/2" pipe. I'm not saying that everything in the process was aluminum, just, the conduit, boxes, etc. Perhaps there is another reason, but I don't know it. You definitely sound like you know more about this. I was just throwing my two cents in.
That said, there must be a reason right? Thoughts?

Sparky Joe

Just curious Goose, what year are you?

goose134

I topped out three years ago.

goose134

Joe, I wanted to apologize. I realized what you were saying when You said that any conductor can induce a voltage, ferrous or otherwise. Duh, copper isn't ferrous either and it induces a current just fine. I was hung up on the magnetic part of it, and how aluminum isn't magnetic. That said, any thoughts on why aluminum pipe? Is there some kind of frequency hysteresis effect on steel conduit? I really do want to know. Again, I apologize for my ignorance. My head hangs with shame.

Sparky Joe

I saw that you're IBEW, so I knew you know this stuff, just perhaps weren't taught it yet. But I meant no offense.

As far as aluminum conduit, I've only heard of it being used in corrosive environments and have never worked with it myself.

goose134

No offense taken, Joe. I looked in the Chicago Code and found no requirement for aluminium, but it does require non metallic on the secondary (hope I'm reading this right). As for the high freq. power issue, I've been trolling engineering sites, aircraft sites, and others and have found nothing about alum. conduit. There is a lot of noise about magnetic flux and such, but apparently it's all regulated internally. I'll keep looking, but who knows, it might turn up something.

randomkiller

I spent most of this past week working on a Verizon switch site. All the conduit in the switch room is aluminum. So yesterday I asked one of the engineers that came out to check on progress why they spec'd aluminum. He said there are two reasons. First of all, it provides a better ground than steel, he said if they made copper conduit that's what they would spec. Secondly (according to him) it cuts down on harmonic interference.

goose134

Thank you for that answer. Like I said, I've been trolling about in the high minded engineering sites and have found nothing relating to the high freq question specifically. I did find a section on one site called 'ask a rocket scientist', but I haven't heard back from them yet. Are the Verizon sites running high freq as well?

randomkiller

Technically no, but the power supplies we are connecting to are dc and then they have their own self supplied and maintained battery bank. The power supplies are very similar to the ones in a computer, full of all types of filters and over sized rectifiers. We are running power to all the racks / cabinets and installing flourescent lighting throughout the switch room. The light switches are threeways mounted in the end panels of the cabinet banks. There is plenty of conduit mounted on the cable trays, racks, and cabinets. I also asked if aluminum was so important, why the cabinets themselves are steel, I got no answer.