Conducting Arc Flash Study in a Testing Area

SJS_421

New Member
Aug 7, 2018
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#1
Scenario - A manufacturing company that makes industrial control panels for a variety of their customers has a testing area in their manufacturing facility where control panels are energized and tested. The rated voltage and frequency of control panels vary from 120-600VAC. Rated frequency varies from 50-60Hz. There are dedicated testing personnel who carry out functional testing on these panels on a day-to-day basis. There are transformers inside these control panels which step down the main power coming in to several lower levels and distribute within the control panel. The control panels are highly complicated with multiple compartments and number of components ranging from 100-400. Testing personnel follows proper lock-out tag-out procedures and wear arc rated gloves while measuring voltage during testing. Because of the nature of the business, all projects are unique and control panels are built in all different sizes and shapes. Hence the distance from an exposed live part inside an energized control panel to the face or chest of the testing personnel is not constant.

There is obviously the existence of electric hazard. But, when system variables (voltage, distance to an exposed live part etc) are varying always, how should arc flash study be conducted? How can appropriate PPE be recommended to the testing personnel or how do I make sure that the existing PPE requirements are sufficient?
 

Hugh Hoagland

Moderator
Staff member
Dec 30, 2016
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Louisville, KY
www.arcwear.com
#2
This is a pretty common problem. AR gloves do not provide shock protection. They are for arc flash protection only. IF contact could be made with the parts, the AR gloves could allow the worker to be shocked but would provide protection from the arc flash.

I would recommend a "boundary study" to find the worst case scenario for this current level the potential clearing times and dress appropriately. There may be VERY limited current depending on the size and impedance of the transformer but the study should give you the maximum scenario. e-Hazard engineers have done many of these types of studies but most have limited incident energy because the control panels don't require much current for the tests. However the shock and arc flash hazard are critical to explore. If the energy exceeds 1.2 cal/cm², we'd recommend to look at the fast clearing device upstream to reduce the energy.