NFPA 70E TABLE 130.7(C)(9) Interpretation

Per NFPA 70E TABLE 130.7(C)(9):
Panelboards or Switchboards rated >240V and up to 600V (with molded case
or insulated case circuit breakers)

Circuit Breaker (CB) or fused switch operation with covers;
-----HRC Cat 0
-----Rubber Insulating gloves (N)
-----Insulated and Insulating Hand Tools (N)
Questions:
1) If the HRC is changed from 0 to 2 or 3, do you have to wear Cat 2 or 3 PPE to close and open a breaker even if the panelboard and circuit interrupting capacity is rated above the above the available fault.

By "changed" I assume you mean you did an Ei calculation and thats what the results were. The answer is yes, even though the analysis assumes the covers are removed the enclosure is not designed to contain an arc flash and it is not safe to assume it will, nor are there any covers on calulations. So yes, you need to wear the PPE your analysis results say to wear, or operate the breaker remotely outside the arc flash boundary.

It is safer to wear the PPE but I am not sure it is required with covers on. NFPA says that gear that is subject to rapid and drastic changes in energy levels require PPE even with covers on. This has been interpreted as 'Switchgear'. A panel board isn't switchgear. Arc Flash is generally assumed to be associated with 'live work' unless specially cited like above. So technically you may be able to operate without PPE with covers on. The point is 'should' you knowing that the energy level is that high?

IF you are maintaining the equipment and it is in good condition and you are using it in the manner in which it is designed, then you should not need to wear the PPE calculated for the cover removed. This is based on an interpretation I received from a member of the 70E Committee and is based upon the FPN #1 under the definition of arc flash hazard in Article 100. It is safer to wear the PPE and appropriate precautions should be taken, but it is not requried.

TxEngr

Our existing practice right now is anybody in the plant are accessing and using the panelboard switch rated circuit branch breaker to turn on/off 480 V lighting, 480V 400/200/100/60/30 amps outlets and some of these panels has a HRC ranging from Cat 0 to Cat 4.

It seems he is using the tables, in which case they need to wear the PPE the tables require with the covers on. I think you have convinced your self the is no arc flash hazard with the covers on based off a FPN, that is not the case, not until the 70E comes out and says otherwise.

But the FPN is a part of the standard and seems that TxEngr has discussed this and gotten an interpretation, from one member. Whether in writing or not is a good question. Maybe not an "official" interpretation but none the less at least appears to represent one committee members intent.

As you are aware by now, I believe that operating properly installed and maintained equipment with the covers on should not be a big deal. It is done every day of every week and no one takes pictures because nothing happened. Granted the equipment is not designed to contain an arc flash, but if it operates properly, it does not need to.

Please do not show me pictures.

If it doesn't, we don't know what the IE is anyway......at least I don't. Extrapolating our best guess of what it is with the covers off to covers on just doesn't work for me.

I think that arc flash hazards originated from live work on open equipment and somehow it has now become a hazard to operate a breaker in an enclosed panel or switchgear lineup.

BTW Zog.....I owe you lunch! Burger King OK?

The FPN is not part of the standard, not enforcable anyways. I have talked to several 70E commitee members , including the ex-chair, and have received completely different views from them. There is a reason they put "doors" closed with HRC's in the tables, they know it is a hazard.

True, but they also fail everyday, thats when they call me.

I got some brand new ones this week, GE AK breaker failures, kaboom!!

Me either, in fact some will argue the hazard is greater with the doors closed, the pressure builds up and releases like a bomb when the door hinges (Or whatever) fail. Maybe less heat but more pressure? Who knows for sure? We need more testing.

Look at all of the OEM's, spending millions on development of arc rated switchgear, thats because they know the truth.

Agreed, and I think it has gone to far in some cases. Switchgear is dangerous, a lighting panel in a warehouse is not IMO.

I don't eat that stuff, how about a good local hole in the wall BBQ place?

Zog,

I have not 'convinced myself' that there is no arc flash hazard when the covers are on. I do believe that when equipment is maintained and operated in the manner in which it is designed, the hazard a dramatically reduced. But when people ask what the requirement of 70E is, I think we should tell them and then add our opinion about what is safest. In my plant, we wear PPE when performing switching operations on switchgear, even when only HC0 is called for. We're safer than what is required. On the other hand, I don't expect people to suit up in HC4 PPE to turn on a 240V breaker in a panel or operate a welding disconnect switch in the field. I use the requirements as the base, and then step it up from there.


TxEngr