I am trying to determine different Arc Flash PPE levels for different tasks around our facility. I have having a full Arc Flash study completed to identify the different Incident Energy at various equipment in the plant.
The next question I ask myself is how to define the arc flash and PPE levels for the different tasks that may be performed on a piece of equipment. For instance lets look at a piece of switchgear that may have a completely different set of hazards for racking in a breaker vs simply looking at a panel mounted meter display.
To define the different PPE levels required for different tasks around a piece of equipment I'm looking at table 130.7(C)(9) in NFPA 70E. For a given type of equipment it shows the PPE levels appropriate for different tasks. However this table assumes a certain avaliable fault current and clearing time to derive these PPE levels. If my Arc Flash study shows that there are higher avaliable fault currents or longer clearing times resulting in higher IE and PPE levels then how do I take this PPE level from my Arc Flash study and corroloate it to the different activities in this table?
As an example for Metal Clad Swgr at 1kV the table shows that to work on energized electrical conductors for control circuits 120V or below exposed only a PPE level of 2 is required. However what if my Arc Flash study shows higher values for the assumed fault current and clearing time that the table used and lets say my study shows this swgr as a category 3. Do I need to change the working on control circuit from a category 2 to 3? Do I need to change all activities in the table to have a minimum of PPE level 3 or can some of them stay what is stated in the table regardless of Arc Flash study results? Would the Arc Flash study simply give PPE values only when involved with working with or involved with energized conductors at the equipment voltage levels.
I'm intersted to hear from others once Arc Flash levels are establised at equipment how you go about defining what is required for different tasks involved with that equipment.
The next question I ask myself is how to define the arc flash and PPE levels for the different tasks that may be performed on a piece of equipment. For instance lets look at a piece of switchgear that may have a completely different set of hazards for racking in a breaker vs simply looking at a panel mounted meter display.
To define the different PPE levels required for different tasks around a piece of equipment I'm looking at table 130.7(C)(9) in NFPA 70E. For a given type of equipment it shows the PPE levels appropriate for different tasks. However this table assumes a certain avaliable fault current and clearing time to derive these PPE levels. If my Arc Flash study shows that there are higher avaliable fault currents or longer clearing times resulting in higher IE and PPE levels then how do I take this PPE level from my Arc Flash study and corroloate it to the different activities in this table?
As an example for Metal Clad Swgr at 1kV the table shows that to work on energized electrical conductors for control circuits 120V or below exposed only a PPE level of 2 is required. However what if my Arc Flash study shows higher values for the assumed fault current and clearing time that the table used and lets say my study shows this swgr as a category 3. Do I need to change the working on control circuit from a category 2 to 3? Do I need to change all activities in the table to have a minimum of PPE level 3 or can some of them stay what is stated in the table regardless of Arc Flash study results? Would the Arc Flash study simply give PPE values only when involved with working with or involved with energized conductors at the equipment voltage levels.
I'm intersted to hear from others once Arc Flash levels are establised at equipment how you go about defining what is required for different tasks involved with that equipment.