Arc Gap and Working Distance for Higher Voltages
Arc Gap and Working Distance for Higher Voltages
(OP)
Has anyone given any thought to the appropriate arc gap or working distance for voltages over 15 kV for arc flash studies... say 34.5kV or 69kV? The suggestions by OSHA seem too small in my opinion. If you consider arc gap for 69 kV, they suggest an arc gap of 0.1* V_LG (approximate dielectric strength of air). That comes out to only 4". If you look at youtube arcing videos, arcs are far longer than 4". As energy is proportional to arc gap, that could be a significant underestimation.
15" seems a reasonable assumption of working distance for 34.5 kV (IEEE recommended for 12.47 kV), as people may glove 34.5. What would you consider a reasonable distance for 69 kV? Would you even worry about calculating energy at that voltage?
Thanks for your thoughts.
15" seems a reasonable assumption of working distance for 34.5 kV (IEEE recommended for 12.47 kV), as people may glove 34.5. What would you consider a reasonable distance for 69 kV? Would you even worry about calculating energy at that voltage?
Thanks for your thoughts.






RE: Arc Gap and Working Distance for Higher Voltages
OSHA states a 15 inch working distance for gloving, so that is the value that needs to be used. As far as 69KV, I assume this is hot stick work, so what is minimum stick length used? 3 feet? Of course, that 3 ft is the length of the stick which does not always equate to worker distance as the distance may be shorter based on how the stick is gripped and used.
I assume you are using ArcPro for this?
RE: Arc Gap and Working Distance for Higher Voltages
For the distance to the arc, I utilize two methods. For under 46kV where energized work is allowed, the working distance is 15". Although our safety standards do not allow us to perform energized work above 46kV, I utilized the MAD (from OSHA) as the working distance since the MAD must be observed at all times. This allows for the scenario where perhaps distribution under-build is being worked energized with both circuits set to hot line mode.
RE: Arc Gap and Working Distance for Higher Voltages