Hello,

I was wondering if anyone could shed some light on what is meant in Art 130.3, 3rd paragraph,:

The arc flash analysis shall take into consideration the design of the overcurrent protective device and its opening time, including its condition of maintenance.

Specifically,

1. What is meant by design of oc device?
2. What is meant by condition of maintenance?

My thoughts are that for design its a difference of a fuse or breaker and if a breaker, then has it been excercised (MCCB) or followed the manufacturers recommendation.

For the maintenance, if there is not an established maintenance program for the equipment, what is one to do for an analysis? Go to next upstream device, assuming the closest device fails?

1. Good question. Could they be talking about current limiting devices?
2. If breakers are not maintained they could fail. Depending on the condition of the breakers, you may want to consider going to the next upstream device. I have seen several drawout type breakers that just absolutely would not operate as they were supposed to. You would have to get an idea of what kind of condition they were in.

I have seen hundreds that didnt operate when they were supposed to, IEEE estimates that >75% of power circuit breakers that have not been maintained per manufacture recomendations in the last 5 years will not pass testing, I think that # is a little high but you get the idea. Thats why testing is critical to the cvadility of your arc flash analysis and has been incorperated into the 2009 70E.

Or if the problem is on the line side of the breaker?

Alan

Standard Interpretations

A couple of links from osha interpretations

[url="http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=INTERPRETATIONS&p_id=25973"]http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=INTERPRETATIONS&p_id=25973[/url]


[url="http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=INTERPRETATIONS&p_id=24617"]http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=INTERPRETATIONS&p_id=24617[/url]