2015 70E-130.5 Arc Flash Risk Assessment-Hazard ID, Likelihood, PPE, Incident Energy

[apee]

My understanding is that Arc Flash Risk Assessment is comprised of two components: hazard identification and likelihood of occurrence of that hazard.

The company I work for is paying a third party to calculate the incident energy value and arc flash boundary for all switchgear, panelboards, MCCs, etc. This is the hazard identification component. We still need to determine the likelihood of occurrence of those hazards.
Do we use 70E Annex F to determine the likelihood of occurrence? If so, can someone point me to information that explains, in detail, how to correctly use this annex? Any information that you?ve found helpful would be appreciated. I?ve searched online for a few hours only to find there aren?t many detailed examples on how to execute the procedure.

Also, 130.5 (C) (1) says, ?Arc-rated clothing and other PPE shall be used by the employee based on the incident energy exposure associated with the specific task.?
The calculations show an incident energy value at a particular place on the equipment, for example such as the load side of a main breaker on an MCC. It doesn?t account for any specific task. Is the PPE level related to the specific task and calculated incident energy?

Thanks

 

[zog]

You can't mix the task tables and your arc flash study results.

 

[apee]

Understood. We can?t use the tables since the incident energy is being calculated. Once the calculations are completed, we?re going to bring in a consultant to assist us with determining the likelihood of occurrence component. I guess he?ll use Annex F as a guide. Thus the reason for my questions. I need to have an understanding of how hazard identification, incident energy values and likelihood of occurrence all come together to determine when and what level of PPE is required. I?d like to read some reference material on how to execute an assessment using Annex F, but can?t find much. I admit that I?m not an expert in arc flash analysis, but am diligently trying to increase my knowledge.

 

[cornbread]

In my humble opinion you need to get the likelyhood of occurance out of the conversation. The likelyhood of an arc flash... in general is low but the consequences are very very high. NFPA 70E wants the persone working in the arc flash boundry to be protected from that 1 in 10000 chance a arc flash occures.

 

[wtucker]

Likelihood CAN'T be left out of the equation. From 70E Art. 100, the definition:

"Risk Assessment. An overall process that identifies hazards, estimates the potential severity of injury or damage to health, estimates the likelihood of occurrence of injury or damage to health, and determines if protective measures are required."

 

[petersonra]

Likelihood CAN'T be left out of the equation. From 70E Art. 100, the definition:

"Risk Assessment. An overall process that identifies hazards, estimates the potential severity of injury or damage to health, estimates the likelihood of occurrence of injury or damage to health, and determines if protective measures are required."

I agree you have to assess how likely an event deemed hazardous is.

I am of the opinion that regardless of how unlikely an event is, if it poses the risk of serious injury or death, you need to find a way to eliminate that risk rather than try and dance around it.

 

[cornbread]

Likelihood CAN'T be left out of the equation. From 70E Art. 100, the definition:

"Risk Assessment. An overall process that identifies hazards, estimates the potential severity of injury or damage to health, estimates the likelihood of occurrence of injury or damage to health, and determines if protective measures are required."

I stand corrected. The point I was trying to make is the risk may be very low but the severity high. When we 1st implemented 70E at our site, we had a lot of discussion from electrical folks...they have been doing works years without the PPE that 70E requires. It basically boiled down to the risk assement. Low risk ... high severity.