HRC Category/ PPE Ratings

[Coachmike]

We are working in a data center switchgear that has never been shutdown. We are scheduling the first ever shutdown, for sometime in May, to install two 480V breakers 1200AF/ 1000AT. We need to open the panel to inspect the bus bars and determine what bus ties etc. may be needed. The Arc Flash Incident Energy calculates to 118cal/cm2. How can we safely perform this inspection without shutting down the switchgear?

 

[mayanees]

Inspection Interaction

Inspection Interaction

You only need adequate PPE for opening up the enclosure. You could increase your working distance while opening the enclosure cover to a point where the Incident Energy (IE) is reduced to the level of your PPE. In this case you might wear a 40-calorie suit while maintaining a working distance of 36 inches from the arc-flash point source. Do your own calculations, but mine are pretty close. It really comes down to your estimation of the risk in opening the cover, in my opinion. This is to say that I wouldn't risk it if it was one of those old enclosures with the hooks that catch the panel when preloaded and turned to lock. But it would be easy to for example open a door with an extension arm.
Good luck

 

[petersonra]

when the switchgear is shutdown for installation of the new breakers you probably should consider adding inspection window(s) and maybe some inside LED lights. and whatever else would make it simpler and safer for you to work on it down the road.

 

[ron]

Can you redo the calcs with bigger working distance to get a 40 cal/cm^2, wear PPE Level 4, then use poles to open and test to ensure it is de-energized, complete LOTO. Then once confirmed, you can be naked .....

 

[nhee2]

Can you redo the calcs with bigger working distance to get a 40 cal/cm^2, wear PPE Level 4, then use poles to open and test to ensure it is de-energized, complete LOTO. Then once confirmed, you can be naked .....

Sounds like he is not planning to LOTO for the inspection, only the shutdown?

 

[GoldDigger]

Sounds like he is not planning to LOTO for the inspection, only the shutdown?

That is how I see it too. He is hoping that he can find a protection scheme that will allow collecting the information needed for planning while the gear is still hot. I.e. hoping that it can work because he is not directly interacting with the equipment while observing it.

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[Coachmike]

Thank you all, RAB Document below

Thank you all, RAB Document below

Restricted Approach Boundary Plan
Electrical Contractor (LP) personnel certified in NFPA 70E propose to do the following;
[all distances, per 70E, from exposed energized conductors]
1) Meet all the requirements of the ‘Clients’ Method of Procedures associated with this work
2) Enter the Switchgear Room with qualified personnel that will be outside the Limited Approach Boundary (> 3'-6")
3) One 70E certified Electrician (E) will wear complete PPE for the exposure, of 40cal/cm2
4) Same individual (E) will remove the panel/ breaker cover/s from "Existing Distribution Panel DP-EP East"
5) (E) will perform a visual inspection and hang insulating blankets if needed
6) (E) will then take photographs of the bus bars and breaker connections within the Limited Approach Boundary (< 3'-6" to > 1''-0")
7) (E) may enter the Restricted Approach Boundary (< 1'-0" to > 0'-1")
8) (E) shall not enter the Prohibited Approach Boundary (< 0'- 1")
a) LP/ Supplier will ascertain what is needed, during a future scheduled shutdown, to install "1200 AF, 800 AT Breaker" for Data Center HVAC Upgrade Project
b) LP/ Supplier will ascertain what is needed, during a future scheduled shutdown, to install "1200 AF, 1000 AT Breaker" for UPS Upgrade Project
9) LP will confirm with Supplier/ Circuit Breakers Manufacturers Rep that all information is obtained to confidently provide all materials needed for breaker install during the future scheduled shutdown
10) (E) will then re install breaker/ panel covers
11) All personnel will leave the switchgear and switchgear room closed and secure
12) LP personnel will check with ‘Client’ that all is normal and close out the MOP referred to above

This is my first stab at this. I'm an old dog but willing to learn new tricks, especially safe ones...

 

[mayanees]

Restricted Approach Boundary Plan


8) (E) shall not enter the Prohibited Approach Boundary (< 0'- 1")


This is my first stab at this. I'm an old dog but willing to learn new tricks, especially safe ones...

One thing I see that is inappropriate is the reference to a Prohibited Approach Boundary. This boundary went away with the 2018 edition. I also don't think there is any reason to cross the Restricted Approach Boundary. If that boundary is crossed, then an EEWP is required. Since this is switchgear, the bus should be relatively deep in the gear such that there should be no reason to reach in and cross the RAB.