The information I've found related to clear zones around substations has come from several books on substation design and engineering, nothing really in codes or standards. Easy to find using the search terms "clear zone substation".
I have also found a recommendation to maintain at least a 6' clear zone to prevent encroachment upon the ground ring usually routed on the outside perimeter of the substation fence in addition to a visible clear zone of 20' for intrusion detection. Still only a recommendation, not a hard and...
What are the requirements, recommendations or guidelines for the mimimum clear zone on the outside of substation perimeter fencing?
Is the clear zone for maintenance, security, ground grid protection, or other?
Where can I find these requirements or recommendations? Looked in NESC, IEEE...
I appreciate the responses. At our site we don't permit anything other than cables and splices in our manholes. While we have had cables faults, the damage has been limited to small blowouts at the fault site. Protective relaying usually clears the fault within a few cycles. We usually have to...
It has been suggested by some of my colleagues that IEEE 1584 equations can be used to calculate the incident energy resulting from a faulted MV cable in a manhole. Am I correct in my understanding that the equations in IEEE 1584 are only applicable to a fault between conductors having an air...
After reeviewing NFPA 70E for the umpteenth time, I realized that the Flash Protection Boundary definition is an approach limit at a distance from exposed live parts (not just energized parts)....
Also the requirements in 70E, Art. 130.6(F) for Confined or Enclosed Spaces is based on the...
rbalex,
After talking with our local utility, they confirmed the scope limitation of 90.1(B), (5)b and c in that they don't apply the 70E arc flash guidelines per se to their utility work. Although OSHA requires PPE they aren't explicit like 70E on what to use. However, I have seen some...
rbalex,
I agree with everything you've said and understand the nuances and inconsistancies with 70E regarding arc flash, and the confusions on shock and arc flash bondaries resulting from misinterpretations of "energized" and "exposed energized". What I don't understand is how utility workers...
We have a complex underground medium and high voltage distribution system to distribute power to more than 200 facilities at our center. 6.9 kV and 22 kV cables are routed via ducts and manholes to intermediate distribution switchgear and then on to unit substations at each facility. It has...
