First time poster. I have a situation where I have contractors entering a manhole to pull cable. The manhole is equipped 7.2 kev lines, the conductors are not exposed. They plan to enter the manhole using ARC Flash PPE to lay down insultated blankets over the cables. After that they plan to work without ARC flash PPE. Does the following statement from NFPA 70E preclude the use of ARC Flash PPE Protection? Any help greatly appreciated.
(F) Confined or Enclosed Work Spaces. When an employee works in a confined or enclosed space (such as a manhole or vault) that contains exposed energized electrical conductors or circuit parts operating at 50 volts or more or where an electrical hazard exists, the employer shall provide, and the employee shall use, protective shields, protective barriers, or insulating materials as necessary to avoid inadvertent contact with these parts and the effects of the electrical hazards. Doors, hinged panels, and the like shall be secured to prevent their swinging into an employee and causing the employee to contact exposed energized electrical conductors or circuit parts rating at 50 volts or more or where an electrical hazard exists.
Without knowing all that may be down there and what sort of protection is in place, what they plan on doing from the electrical stand point sounds very reasonable. I have seen situations below grade where when things were first installed they were properly protected but over time the protection has corroded away. It sounds like on one hand they are over killing things, but on the other they sound smart and anticipate possible problems. I think they could decide the mats are overkill once in and determinimng the site safe.
This all assumes you mean 7.2kv (7200 volts) and not 7.2 kev (7200 electron volts) which I am sure is less than the voltage that is created by air flow through my nose when I sneeze.
There are additional OSHA confined space entry requirements and permits (at least for us in the Government) dealing with oversight, rescue ect. We have training on it, but it has been some time since I took it (I am not typically involved).
Sorry that I can not give you better information. I hope that this at least gives you a place to start and those more knowledgable step in to help.
This is just my two cents. I work with 4160v through 34.5kv in underground situations every day. because I work in the mining field I fall under the 30 cfr instead of the 29 cfr, but we do adhere to the 70E standards, so take what I have to say for what it is worth. First thing, I would set up an emergency retrieval tripod with a winch rated for twice the wieght of the largest man. I would put a harness on anyone heading into the vault so I could pull them out in an emergency by my self. I would set up ventilation on site and have fresh air blowing into the vault for at least 10 min before entering. I would drop a gas meter into the vault to make sure there were no deadly gases left in the vault where I was sending myself or my men. Next I would have my men in the appropriate PPE for the voltage present, lower them in, cover the exposed lines with blast blankets, remove the flash suit, and put the retieval harness back on. After finnishing the job required I would have them put the flash suit back on, remove the blanket, clean the vault, and hoist them back out. Then clean the site, reinstall the vault cover, and then test the new circuit.
I know my approach may be a bit lengthy and time consuming, but a life is never worth less than money.
You might want to even sit down for five min and do a pretask plan to make sure everyone is in the same frame of mind and noone has missed any of the site specific hazards.