Labeling 208 V panels

[CCS]

I am currently negotiating with an A&E company, that I feel is qualified and experienced in project of our size and type, to perform an Arc Flash Harzard Analysis. My specs originally included all panels in the 3 ph system to be analyzed and labeled. Costs were above expected, so to reduce I asked the vendor to cut out 208 v panels fed by xfmrs <125 kVA. That reduced cost, but now those panels will have no labels.

Also, the vendor suggested to cut the Protective Device Coordination study on the grounds that I have very few CB that would have adjustments and therefore have little control of the outcome, other than replacing equipment.

Any comments or suggestions before this deal gets sealed.

 

[jim dungar]

NFPA70E effectively requires all panels to be labeled even if they do not need to be "studied". If workers are 'interfacing in a manner that could cause an arc', they need to know what PPE is required to protect themselves.

If I had to save money, I would 'skimp' on the coordination study, especially for an operating facility that is not experiencing 'unexplained tripping'.

 

[CCS]

Labeling 208 v panel

Labeling 208 v panel

Is there a code section in 70E that I can refer the vendor to that states all panels must be labeled? Or is it implied that the employer, or host employer, must inform employee's and contract employers of known electrical harzards in the workplace?
Have about single phase panels? Would they be lableled with a category according to the task being performed? (Table 130.7(C)(9))
As I'm looking at the code book, while writing this reply, I see section 130.3(C). "Equipment shall be field marked with a label containing the available incident energy or required level of PPE." And when you look at the definition of Equipment, it does not look like much is left out. Do I have the right picture?:?

 

[charlie b]

. . . so to reduce I asked the vendor to cut out 208 v panels fed by xfmrs <125 kVA. That reduced cost, but now those panels will have no labels.

Label them as "Category 0."

Regarding a coordination study, you don't need that, unless you have an emergency or legally-required standy system for which you are required to show coordination. Otherwise, all you need is the present setting of each circuit breaker that feeds any of the panels of interest.

 

[jim dungar]

Label them as "Category 0."

On what basis?

NFPA70E is pretty clear about it, perform a study or use Table 130.7(C)(9) which shows that some tasks require Category 1 PPE.

 

[charlie b]

I don't have my reference materials handy, Jim. Acting only on memory (a hazardous practice, I confess), I based "category 0" on a statement somewhere within the arc flash rules to the effect that panels rated under 250 volts and fed from a single transformer rated no higher than 125 KVA will always calculate out to a category 0. So I infer that you can label them as such, even without performing a calculation.

Can anyone confirm or correct my memory on this issue? :?

 

[jim dungar]

I don't have my reference materials handy, Jim. Acting only on memory (a hazardous practice, I confess), I based "category 0" on a statement somewhere within the arc flash rules to the effect that panels rated under 250 volts and fed from a single transformer rated no higher than 125 KVA will always calculate out to a category 0. So I infer that you can label them as such, even without performing a calculation.

Can anyone confirm or correct my memory on this issue? :?

In the 2004 edition of 70E, there was an exception that allowed you to reduce a task table value by 1 level if the fault current was sufficiently low. This exception was removed in 2009.

 

[charlie b]

That is not the "rule" I was talking about. I will try to find something that backs up (or backs away from) my memory.

 

[jim dungar]

I will try to find something that backs up (or backs away from) my memory.

I hope you are successful.

NFPA70E-2009
130.3 - a flash hazard analysis shall be performed to determine boundary and PPE.
__ex #1 - analysis not required for <125kVA, <240V
__ex#2 - use tables 130.7(C)(9) etc., if an analysis is not performed.
130.3(A)(1) from 50-600V, use a 4ft boundary if analysis is not performed.
130.3(C) equipment shall be labeled, so PPE can be selected.

 

[zog]

On what basis?

NFPA70E is pretty clear about it, perform a study or use Table 130.7(C)(9) which shows that some tasks require Category 1 PPE.

This is correct, some tasks are HRC 1. I also want to mention (Not directed at anyone in paticular) that these HRC's from the table can only be used if you fall within the limits of the tables, so to find out you have to at least figure out your fault current and clearing times. If you exceed the limits (Note 1 in this case), you have to perform an analysis anyways.

To make this even more interesting, here is the 2012 70E verbage that is replacing the 2009 "execption".

"An arc flash hazard analysis may not be necessary for some three-phase systems rated less than 240 volts. See IEEE 1584 for more information."

 

[jim dungar]

I also want to mention (Not directed at anyone in paticular) that these HRC's from the table can only be used if you fall within the limits of the tables, so to find out you have to at least figure out your fault current and clearing times.

Absolutely important.

Many small single phase systems will easily meet the fault current level, but they will fail at clearing the fault in less than 2 cycles.