Arc Flash PPE required

[sticko]

We have completed an arc flash coordination study, so I have the incident ratings for all of the breakers and switches. Now if the incident rating for a circuit breaker is 33 cal/cm, do I need to protect myself with a 40 cal suit to simply push the open or closed button on the breaker for commissioning testing? Does the arc flash incident rating only apply to open gear and exposed bus?

 

[GoldDigger]

We have completed an arc flash coordination study, so I have the incident ratings for all of the breakers and switches. Now if the incident rating for a circuit breaker is 33 cal/cm, do I need to protect myself with a 40 cal suit to simply push the open or closed button on the breaker for commissioning testing? Does the arc flash incident rating only apply to open gear and exposed bus?

Unless the gear has a specific and justified separate rating for closed door, the calculated incident energy determines the required PPE for an act as simple as pressing the local open or close button.
Remote actuation is OK as long as nobody is within the critical arc flash radius.

 

[GSTeat]

Arc Flash PPE

Arc Flash PPE

NFPA 70E only applies when you have 'live' AND 'exposed' electrical components. Therefore you don't need arc flash PPE to open/close a breaker if the panel is tight and there are no missing breakers or covers.

 

[zog]

NFPA 70E only applies when you have 'live' AND 'exposed' electrical components. Therefore you don't need arc flash PPE to open/close a breaker if the panel is tight and there are no missing breakers or covers.

That is incorrect, the only exception would be arc rated switchgear. Exposed live parts relate to shock hazards, they do not need to be exposed to produce an arc flash hazard. Thats why you see HRC 4 for racking a breaker with the doors closed in the task tables.

 

[youngin]

Hi zog,

You referenced racking a breaker and the tables but I assume you meant to say that "Yes, PPE is required for opening/closing the breaker" as well?

To be clear- lets say a panel board or breaker has a label from a study stating HRC 3 and does not specifically state an exception for operating it with the doors closed. In that scenario the employee should wear HRC 3 equipment to throw the breaker or operate panel switches. If arc rated switchgear was used the label should state the exclusion.

Thoughts?

 

[jtinge]

Remember that incident energy values are not the same as the HRC ratings in the NFPA 70E task tables. An incident energy value only indicates the hazard in the event of an arc flash, it does not take into account the probability of the arc flash occurring based on the task. NFPA 70E requires a risk assessment of the task(s), which takes into account both the probability and the consequence of an arc flash event. Unfortunatety, how to do the risk assessment is still up for debate.

The HRC ratings derived from the task tables do take into account risk, and you will notice that for the same hazard, varying levels of PPE are permitted based on the risk associated with the task. If I remember correctly, I believe I've read that risk was determined based on the collective experience of the committee.

The discussion of risk, the best way to evaluate risk and the need for PPE has been the subject of several detailed discussion on other arc flash specific forums. I would advise checking them out also for further insight.

 

[mayanees]

We have completed an arc flash coordination study, so I have the incident ratings for all of the breakers and switches. Now if the incident rating for a circuit breaker is 33 cal/cm, do I need to protect myself with a 40 cal suit to simply push the open or closed button on the breaker for commissioning testing? Does the arc flash incident rating only apply to open gear and exposed bus?

As previously stated, the 33 cal listing is the hazard. Any interaction entails a risk factor that theoretically could be lessened by plodding through ANNEX F of 70E, Hazard Analysis, Risk Estimation, and Risk Evalaution Procedure.
It's very typical to equate the HRC to the calcualted incident energy level, but the 70E 2012 edition puts that risk assessment on the owner, I think as a way to handle/lessen the sometimes overly stringent requirements.
But in support of this reduced risk associated with just operating the breaker from the front of the gear, Schneider Electric has their Data Bulletin 0100DB0804R11/09, PPE Recommendations Low and MV Equipment Operation/Maintenance. (wouldn't attach.. google it!)
This document lists four different classes of Square D equipment that can be operated from the front of the gear with PPE 0. It qualifies the installation as needing to: Have been commissioned; properly installed, rated and maintained; in operation under load....
But this gives an example of a manufacturer applying the "risk' factor to their gear and determining that the gear is safe to operate, unlike the impression that is given when you stick a PPE Dangerous tag on it. I haven't seen anything similar from other manufacturers.

So if your gear is this Square D class of gear, you could use this information; although the commissioning is not complete until you're finished and it's in operation!

You're probably stuck using remote operators, or the PPE 4 suit

John M

 

[Steve McKinney]

I haven't been on the forum for quite some time and I was hoping to find discussion on this very topic. We have a considerable number of medium voltage(4160) skids with main breakers and motor starters that we are responsible for. This has always been a "fuzzy" area of understanding for me. I appreciate the discussion and reference to the Square D site as I try to better understand the the PPE requirements. Any more references would be awesome at I try to get my head around it.......