Separation between Terminals

[wireddd]

Recently hooked up a 200 hp compressor with seperate starters for starting and running.
This is 480 volt three phase. The separation between terminals where the cable lugs have to go on is only about 1/2 inch between the barrels on the lugs. Does anyone know what the minimum spacing should be for 480 volt?

 

[nakulak]

table 408.56 is a good rule of thumb, but I don't know if it applies or not.

 

[LarryFine]

Triple D, if the equipment is rated for the voltage, they're far enough apart.

That's how I'd look at it, anyway.

Added: I've heard that one inch per kv is adequate, so if that's correct, you're okay.

 

[mcclary's electrical]

table 408.56 is a good rule of thumb, but I don't know if it applies or not.

Does the NEC apply to a manufactured piece of equipment?

 

[nakulak]

Does the NEC apply to a manufactured piece of equipment?

maybe someone else here could answer that - its beyond my small puddle of knowledge. One would think that if the ahj approved of the equipment listing, that at some point the NEC or a higher standard would have applied, but that is just conjecture on my part, and it also assumes (wrongly I suppose) that the NEC contains enough information that a manufacturer would need to adequately build equipment.

 

[mivey]

Not sure what manufacturing specs are but the dielectric strength of air is generally accepted to be 76.2kV/in so 0.02 inches would give you a safety factor of more than 2 just for plain air.

I'm sure there is more distance built in for mechanical movement, dust, manufacturing slop, etc.

 

[mivey]

Found another reference that considers ionization in high voltage circuit boards. It says arcing can occur at 40kV/in for dry air and 20kV/in for humid air with sharp source points.

 

[TT009]

maybe someone else here could answer that - its beyond my small puddle of knowledge. One would think that if the ahj approved of the equipment listing, that at some point the NEC or a higher standard would have applied, but that is just conjecture on my part, and it also assumes (wrongly I suppose) that the NEC contains enough information that a manufacturer would need to adequately build equipment.

Last week at a class I take someone had brought up the NFP 70 or something like that. It was in regards to color of wire to use for wiring for certain voltages in a starter (manufactured) not field wiring.

So I would say the manufactures specs are over the NEC

 

[eric7379]

Is anybody that familiar with the NFPA 79?? Maybe this would have some guidance in it?

I do not know right off hand if anything in the NFPA 79 would cover something like this.