Equipment requiring arc flash evaluation

[joshtrevino]

I am reviewing NFPA 70E at this time to determine what equipment should be included in a plant wide arc flash study for a client. I see throughout the document that certain criterion are contingent on the equipment operating at 50V or more. Is the intent of NFPA 70E to exclude electrical equipment operating below 50V from being required to have an arc flash study done on such equipment?

In other words, should the scope of my arc flash study include all electrical equipment operating at 50V or more for which personnel may be working within the limited approach boundary while the equipment is energized?

If you can site specific articles of NFPA 70E, NEC, or other governing codes, that would be helpful.

 

[jeremy.zinkofsky]

Check out IEEE 1584-2002 "Guide for Performing Arc Flash Hazard Calculations"

It states that you can omit any motors under 50HP and any equipment below 240V unless it feeds at least (1) 125KVA or larger Transformer.

 

[steve66]

I would say yes, normally only equipment above 50 volts.

Arcs probably aren't self sustaining at lower voltages. And they are much less likely to have enough energy to cause a dangerous arc flash since most lower voltage circuits seem to be fused at 20 amps or less.

 

[ron]

Check out IEEE 1584-2002 "Guide for Performing Arc Flash Hazard Calculations"

It states that you can omit any motors under 50HP and any equipment below 240V unless it feeds at least (1) 125KVA or larger Transformer.

A detailed calc might not be needed for that equipment but a label is still required per 70E.

All equipment 50V nominal and higher is what I suggest.

 

[Sunny_92]

A detailed calc might not be needed for that equipment but a label is still required per 70E.

All equipment 50V nominal and higher is what I suggest.

+1