Required PPE per the NEC within a MCC Room

MiltSanders

Member
Location
USA
Occupation
Engineer
First, I am new to NFPA70E and the NEC. I have purchased these materials and trying to learn to navigate and find things is yet a work in progress. I wanted to reach out to you all and ask for guidance in how and or where to look.

Here is what I have: I have an Indoor MCC Room that is 25 feet wide and 75 feet long. The left side has PLC cabinets with doors and PLC hardware installed. All voltage on the left side is 120 VAC or less. On the right side of the MCC room, there are Eaton breaker cans with the breaker disconnect handles sticking out the front (HDK 65K). The right side for the most part is 480 VAC with only access to the components is from the front. There are ARC Flash stickers ranging from 0.5 cal/cm^2 @18" to one that reads 7.3 cal/cm^2@18" with an ARC flash of boundary of 61 inches. There are entry and exit doors at both ends of the MCC. Also, there are “no” live conductors exposed unless bolted covers are removed on the right side and or a PLC cabinet doors are opened and safety covers ignored.

My question is, if all the covers and doors are in place and closed, how can I figure out what PPE is required for passing through this room and doing no work? I have looked through Table 110.26, Table 110.26(A)(1), Table 110.27(C), Table 110.31(B) of the NEC and all I keep seeing is “exposed live parts”. If there are no exposed live parts and the doors are closed and the breaker covers installed and bolted, what PPE is required for my worst situation (7.3 cal/cm^2@18" with an ARC flash of boundary of 61 inches) if I can stay about ten feet away from the ARC Flash Boundary? If someone could help me locate the area in which to locate this information would be very helpful.

Regards,
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
My question is, if all the covers and doors are in place and closed, how can I figure out what PPE is required for passing through this room and doing no work? I have looked through Table 110.26, Table 110.26(A)(1), Table 110.27(C), Table 110.31(B) of the NEC and all I keep seeing is “exposed live parts”. If there are no exposed live parts and the doors are closed and the breaker covers installed and bolted, what PPE is required for my worst situation (7.3 cal/cm^2@18" with an ARC flash of boundary of 61 inches) if I can stay about ten feet away from the ARC Flash Boundary? If someone could help me locate the area in which to locate this information would be very helpful.
We don't follow NFPA70E so I might not be the best person to answer your question but one would think that if all of the covers are on the equipment then no PPE is required to walk through the room.
 

mayanees

Senior Member
Location
Westminster, MD
Occupation
Electrical Engineer and Master Electrician
You want the 70E Table 130.5(C) "Estimate of the Likelihood of Occurrence of an Arc Flash Incident for ac and dc Systems". This will tell you that it is okay to have activity around the gear with doors closed wearing no PPE. It's only when you are interacting with the equipment that you need to be concerned about PPE. For example, you can do Infra Red inspections by having a person suited to the appropriate level (7.3 cals in your case) opening up the panels, then an IR camera can scan the system with the camera-person wearing no PPE but staying out of the Restricted Approach boundary (12 inches) for the application.
 

mayanees

Senior Member
Location
Westminster, MD
Occupation
Electrical Engineer and Master Electrician
... and by the way, you can access a free copy of an NFPA standard, that's NEC(70) and 70E for us, by registering your email address at NFPA.org. Free access is granted to any of the standards that are accessible, although the access seems limited. I pay $99/year for NFPA Link because I do 70E presentations and full access is preferred.
 

MiltSanders

Member
Location
USA
Occupation
Engineer
Many thanks to each of you for assisting me. Also, much appreciated for sending me over to NFPA.Org. I was able to review the standards.
Regards,
 

garbo

Senior Member
First, I am new to NFPA70E and the NEC. I have purchased these materials and trying to learn to navigate and find things is yet a work in progress. I wanted to reach out to you all and ask for guidance in how and or where to look.

Here is what I have: I have an Indoor MCC Room that is 25 feet wide and 75 feet long. The left side has PLC cabinets with doors and PLC hardware installed. All voltage on the left side is 120 VAC or less. On the right side of the MCC room, there are Eaton breaker cans with the breaker disconnect handles sticking out the front (HDK 65K). The right side for the most part is 480 VAC with only access to the components is from the front. There are ARC Flash stickers ranging from 0.5 cal/cm^2 @18" to one that reads 7.3 cal/cm^2@18" with an ARC flash of boundary of 61 inches. There are entry and exit doors at both ends of the MCC. Also, there are “no” live conductors exposed unless bolted covers are removed on the right side and or a PLC cabinet doors are opened and safety covers ignored.

My question is, if all the covers and doors are in place and closed, how can I figure out what PPE is required for passing through this room and doing no work? I have looked through Table 110.26, Table 110.26(A)(1), Table 110.27(C), Table 110.31(B) of the NEC and all I keep seeing is “exposed live parts”. If there are no exposed live parts and the doors are closed and the breaker covers installed and bolted, what PPE is required for my worst situation (7.3 cal/cm^2@18" with an ARC flash of boundary of 61 inches) if I can stay about ten feet away from the ARC Flash Boundary? If someone could help me locate the area in which to locate this information would be very helpful.

Regards,
I retired from a large hospital/research center that had a very strict safety department. We had at least 18 switchgear locations with dual service 13,200 volts. Every week we performed check ups In each room. Recorded Primary & secondary voltages & ampere. For this type of work we were never required to wear any PPE. We always wore PPE rated long sleeve shirts, pants & electrical approved work boots with non metallic toe protection. In one building we had 50 cal PPE for switching & racking in 13,200 volt gear and 40 cal for all others. Cheif electrician always told us to wear 100% cotton socks ( which I never found ) and 100% cotton tee shirts & underwear. We were trying to get them to purchase PPE rated tee shirts. Hope the NEC mandates that all future switch gear rooms have remote operators ( think it had to be 15 or 20' from 13,200 tie breakers & breakers ) so you do not have to wear any PPE just to single end, return power back to both services or secure power. We had this in maybe 6 rooms.
 

Jraef

Moderator
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
With all doors closed and all equipment installed and maintained as per manufacturer’s instructions, you will not need any special PPE to be IN the room. You would if you OPEN A COMPARTMENT DOOR, but that should only be done by a trained and qualified individual.

Then, depending on the design ratings of the equipment involved, you may need PPE to “interact” with the equipment, ie switching a breaker handle on or off from the outside. That needs to be determined via a risk assessment. This is where “Arc Resistant” gear comes into play, because that basically means anyone can interact with the equipment (doors closed) without special PPE, ie that risk evaluation has already been done and covered in the design of the gear. That doesn’t mean non-AR gear is inherently unsafe, it just removes a necessary step in making that determination.
 
Top