Question on Wire Insulation

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jwilson3

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I am in the engineering department of a manufacturer of combinational vacuums for the car wash industry.

My question is what wire do I need to use for 115VAC. I have some wire that will carry ~30 Amps and another that will carry ~4Amps. The 4Amp wire is providing power to the primary side of my transformer. The 30 Amp wire is going to travel approximately 4ft, and the 4amp wire approximately 6 inches. I'm confident with the gauge I'm using just not of the insulation. If anyone could please answer this I would appreciate it. If more information is needed please ask and I will provide.

[ June 09, 2005, 04:28 PM: Message edited by: jwilson3 ]
 
Re: Question on Wire Insulation

this is a scary question because it begs the question - why is someone designing this kind of thing that does not know the answer to such an elementary question?
 
Re: Question on Wire Insulation

The "guage" of the wire (i.e., cross-sectional area) determines the amount of current (amps) that the wire can handle. The danger of excess current is the risk of overheating and damaging the insulation. Therefore, the type of insulation (specifically its ability to resist overheating) has an influence on the amount of current that the wire can handle.

The insulation has only one purpose: to keep the current on the inside, and not let it leak out to the outside world. The choice of insulation depends first on the voltage. Your 115 volt device will probably use an insulation system rated at 600 volts (the next higher standard rating).

But as to which specific type of insulation, that is really more than we can determine for you. It depends very highly on the physical conditions of the installation. Will the wire be subjected to dampness, or to direct water spray? Will it be in open air, or in conduit, or buried underground? If this wire is part of your equipment, then the National Electrical Code would not apply. It would be up to your company (i.e., the manufacturer) to determine what is acceptable, and to perform whatever testing is needed to prove it is acceptable.
 
Re: Question on Wire Insulation

jwilson3
You need to contact a qualifed designer to assist you. The NEC is only for premisis wiring, not plug in equipment. Also, isn't your product required to be listed by a testing lab?
 
Re: Question on Wire Insulation

Thanks for you replies. I am not an electrician, I do not know codes, I was never trained to know codes. So therefore insulting my intelligence isn't very courteous. The wire that I have ordered and actually built protocol machines with has a 600V rating. The electrical engineer over me is Russian, he wasn't sure about the code here in America. Like I stated in my above post. I'm sure about the gauge. This i know from calculations. The insulation we use I know will hold up, just didn't know if I had to follow any certain code. This company has been the world-wide leader in combinational vacuums for a very long time, so its clear that we know what we are doing. We were just wanting to know if we were subject to code being that the wire was a physical part of our machine.

The main engineer here is very stern about knowing for sure we are right. We don't want to jeopardize our companies credit by designing something not up to code. This machine is a total new design. We just wanted to use the correct wiring now, so we wouldn't have to change design when the machine gets inspected.

The engineer is on vacation right now, I am trying to get as much information as I can before he gets back. We are not relying on this forum to design our wiring, i am just coming to you for some advise.
 
Re: Question on Wire Insulation

Charlie B

Thanks for your post. Answered what i needed to know. We aren't required to follow a certain code.

Again thanks for your reassurance
 
Re: Question on Wire Insulation

From a liability standpoint your company should really seek testing and listing by UL or another recognized testing organization for your equipment. Charlie is right in that the NEC does not apply to equipmet that plugs in, however that leaves you without the protection of "meeting code" to ensure the safety of your equipment. If you could prove that your company's equipment meets UL standards; you, your CEO, and your company's lawyers should all sleep better at night.
 
Re: Question on Wire Insulation

Our old design does meet UL. This one will also thats why I am wanting to make sure its right the first time. I hate having to do something twice!!
 
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