racineboxer wrote:
The way I read this thread it sounds like a guy could do voltage testing on this circuit (120 volt, feed from cat 0 panelboard) "bare handed" as long as they are using an insulated tool, such as a Fluke multimeter and I'm just wanting to make sure I'm 100% clear on that and the reasons why
Yes, this is actually called "insulated tools" method. Be careful about the bare hands reference because this is something entirely different. In live line, bare hands methods you actually first move to a floating object position (insulated against both ground and energized line), and then intentionally bond to the line so that you can work on energized lines directly without being insulated. This method is a very specialized work method though. See the following web site for video showing the helicopter variation.
[media=youtube]FrgUZNCkfFI[/media]
Quote:
But what about arc flash protection for category 0? Let's say the arc flash boundary is 13 inches. If your hands go inside 13" to do the voltage testing then they would need some level of arc flash hand protection right? What about if the arc flash boundary was 1", would the use of an insulated tool the allows you to keep your hands back further than 1" mean that you do not need any arc flash hand protection?
100% correct. If you use tools which are long enough that you don't cross the AFB, then there's no PPE requirement for arc flash at least. An example of where this comes in play where I work is that we have some 20 foot telescoping hot sticks. This allows us to reach up to fuse cutouts on a mast and pull the fuses out 20 feet up while being both outside the arc flash boundary and the restricted approach boundary.
Where it gets much more complicated is when you are somewhere in between. Say for instance that you are working on a 24 VDC control power circuit inside a panel which also has a couple 480 V contactors in the same panel. All wiring is built as non-exposed (wires are stripped only to specification). 480 V equipment is calculated as 6 cal/cm^2. This scenario is common in a lot of manufacturing plant controls these days and some machine tool type equipment. It is a bit of a grey area and different people have different conclusions. Obviously no shock protection is necessary, but do you need arc flash protection? In this case since there is no interaction some folks will say no. Others say that just in case to be on the safe side, the answer is yes. Others may say "sometimes"...depending on whether or not there is any reasonable chance of a failure where an energized wire is touching the door but once the door is open, you might be able to dress down. Some also draw a line depending on how far you are away from the 480 V wiring in case you accidentally slip with a tool.