MV short circuit values above 10ka

[JoeStillman]

MC?

MC = My Clumsiness

I meant MV.

You can see why nobody wants me to touch their wires.

 

[petersonra]

MC = My Clumsiness

I meant MV.

You can see why nobody wants me to touch their wires.

I am tempted to say "You can touch my wires anytime you want to", but I think I won't.

 

[Sahib]

On-line work is inevitable in cases, for example, taking voltage measurement. In such a circumstance, special procedure is to be adopted other than basic operation and maintenance procedure. It includes proper PPE, more than insulated gloves and hotsticks for MV/HV works.

 

[Sahib]

OHSA mandate for protection of utility line man against arc flash is mentioned in this article.
https://googleweblight.com/I?u=http...tility-linemen-from-arc-flash-events&hl=en-IN

Sorry. There was error in the above url. The corrected url is as below.


https://googleweblight.com/i?u=http...tility-linemen-from-arc-flash-events&hl=en-IN

 

[mbrooke]

Ok- big update, from another member on another site- huge help (see pic)


Now comes the question how 4 cal vs 8 cal plays out? And why only assume L-G?

 

[JoeStillman]

I am tempted to say "You can touch my wires anytime you want to", but I think I won't.

:lol:

 

[kwired]

PPE is not intended to prevent injury. It is intended to keep you from non-recoverable injury. It is rated in Cal/cm^2. Not voltage or current.

Utilities per se do not have to follow NEC 70E, but OSHA would definitely stick their nose in. I wouldn't want to be the guy on the stand being asked the question:

"So, one of your workers was killed, correct"
Yes.
"Was he wearing proper PPE"
Well, I don't know. We hadn't done an arc flash assessment.
"Why is that?"
We are a utility, and arn't governed by the NEC
"So, you had them work on hot lines, without proper safe guards?"
Well, we told them to be careful.
Your honor we request our clients family be awarded $300 Million Dollars; Granted.

AFAIK nobody is required to follow 70E, but doing so is the easiest way to comply with what OSHA does require. One can create their own safety standard but it will take a lot of time and effort to establish it and keep it up to date with new technology or findings, simply using 70E lets someone else do all that work of keeping things up to today's needs. There may possibly be other publications that do about the same thing out there but 70E is most popular.

I don't believe utilities necessarily are always required to follow NESC either (might vary State by State), but is good decision to follow such a standard for legal and liability reasons.