How do you/your company measure the “working distance� that is used in an arc flash study and also placed on labels?

The working distance is the distance from the worker’s head and torso to:

• The front of the electrical equipment enclosure
• Energized conductors that could be the source of an arc flash
• Something else (please comment)

NFPA 130.5(b)(1)

Correct. However, there are rumblings that defining the source of the arc is difficult and varies and some are talking about making it from the front of the equipment. It looks like 2 votes so far use that. However, the reality is the incident energy is the energy that makes it from the arc to the person - Just like the present defintion.

I'm not sure if a revised definition will gain much traction because it will really create confusion but I'll keep you posted if it gains momentum (which I doubt)

We take advantage of the actual distance when we can, but we use the enclosure surface for our labeling process, so that is how I voted.

If you have a 36" deep 480V switchboard with cross bussing located about 3" from the back of the board, but there are fuses located only 10" from the front - what distance do you put on the label?

But, if you are working in a multi-door enclosure with the only energized conductors being the shielded line side of the main disconnect in the upper right hand corner, then adjusting the distance found on the label makes good sense.

This is what stirred the discussion. It's no secret the working distance is from the arc to the person but the implementation sometimes causes confusion so a few (not me) are questioning what can be done about it. That's actually the reason behind this weeks question. - To see if everyone uses the standard working distance definition.

Thanks for the input everyone!

Another question might be - how many use the IEEE 1584 "typical" working distances (also default values in most software) instead determining the actual working distance for each item of equipment. Determining the actual working distance at each type of equipment for a large facility would take an inordinate amount of time and make the cost of a study unacceptable.

It looks like most people use the IEEE working distance from an [url="http://arcflashforum.com/showthread.php?t=1360"][earler survey question][/url]
I agree, trying to measure the actual distance would be a bit difficult and I'm sure create a greater hazard for the data collection. I must admit the origin of this question was not me. There was a bit of discussion from others so I thought I would post it.

I don't think much will come of this anytime soon if at all and I'm not sure it should. It is interesting to see what people's thoughts are.