Intelligent Power Today Magazine

Answering frequently asked questions about arc flash relays

BY BOB ZWEIFEL, Littelfuse

The dangers of an arc flash incident—burns, blast, molten metal ejected at ballistic speeds—are by now familiar to every electrical worker. Most electrical professionals have read about strategies to minimize arc flash hazards, including arc flash relays. Now many of them are seriously considering integrating arc flash relays, but they have many questions about how to install this unfamiliar technology and exactly what the benefits will be.

Electrical Source Magazine and Littelfuse, based on the company’s frequently asked questions, offer some insight on how to apply these valued...

Absence of voltage testing is a vital step in the process of verifying and establishing a de-energized state of any electrical system. As detailed in NFPA 70E clause 4.2.5., there is a specific and approved approach to establishing an electrical safe work condition with the following steps:

• determine all possible source of electrical supply
• interrupt the load current, open the disconnecting device for each possible source
• verify where possible that all blades of the disconnecting devices are open
• release or block any stored energy
• apply lockout device in accordance with documented and established work procedures
• using an adequately rated portable...