over 600V equipment - cutouts 6

[db1979]

I'm dealing with an old building on a campus that has 2400V distribution distributed in tunnels around the campus. 2400V power distributes to several individual vaults located below the different buildings on the campus. The campus is under its own jurisdiction, so it's hard to say how much oversight the installation of the electrical distribution has had. I typically work with 480V power, so I've briefly had to look through the "over 600V" code to see if there's anything I need to rectify in the vault. The vault I'm working in utilizes cutouts where the 2400V power enters the vault. Section 490.21(C)(1) indicates that "distribution cutouts shall not be used indoors, underground, or in metal enclosures."

I've also found an OSHA article that indicates the following:

1910.308(a)(5)(iii)
"Fused cutouts installed in buildings or transformer vaults shall be of a type identified for the purpose. Distribution cutouts may not be used indoors, underground, or in metal enclosures. They shall be readily accessible for fuse replacement."

why would is say "installed in buildings or transformer vaults" if cutouts are not allowed to be installed indoors? I may be dealing with a nomenclature issue as well, as the "cutouts" appear to just be current limiting fuses/disconnect switches that can be opened/closed via an insulated handle.

any insight would be greatly appreciated!

 

[jraef]

First off, it sounds as though you are in the US. If so, are you doing any work or just looking at and making assessments? If doing work, you need a Medium Voltage Splicing Certificate to do anything with the cables. If only observing and assessing, hopefully you are fully aware of theconsiderable new PPE requirements just to be in the same room as MV equipment.

That said, you may be missing the subtle difference in those statements. "Distribution cutouts" are not the same as "fused cutouts" used in transformer vaults etc. They are the open style devices that are used on utility poles and switchyards by the utilities, operated from the ground by a lineman with a long fiberglass pole.

Distribution cutout:

Fused cutout in a transformer vault:

Still operated by a pole.


And sometimes people use the wrong terms for what is being implemented. If it is an enclosed switch with its own handle on the outside, it's more likely a Fused Load Interrupter Switch:

Or if you are not sure if there are fuses inside, a Vacuum Switch, an SF6 gas switchor even an Oil Switch, (although usually for 15kV class systems, they are sometimes used at lower voltages, especially underground).

And here is why the code says that you can't use open style distribution cutouts indoors...

"Dear future generations: Please accept our apologies. We were rolling drunk on petroleum."
— Kilgore Trout (via Kurt Vonnegut)
For the best use of Eng-Tips, please click here -> faq731-376

 

[DTR2011]

LPS to Jref simply for the excellent use of the new system, including the pics!

OK, the explanation was pretty good as well.

 

[DRWeig]

Another kudos to jraef. Exemplifying the spirit of eng-tips.com, and also answered a bunch of questions that I never had need to ask.

Good on ya,

Goober Dave

Haven't see the forum policies? Do so now: Forum Policies

 

[AgeXVII]

I'll bite as well, I didn't know or need to know (right now) but well played with the picture examples and explanations. I would probably be entertained by a power point presentation created and given by you as well jraef!