appnotes1

APPLICATION NOTES

VOLUME 4

ARC FLASH STANDARDS OVERVIEW
 

WHAT ARE THE INDUSTRY STANDARDS THAT COVER ARC FLASH?

There are four main regulations that govern electrical safety and arc flash (note: this is not an exclusive list and regulations are subject to change):

1. OSHA Standards 29-CFR, Part 1910. Occupational Safety and Health Standards. 1910 sub part S (electrical) Standard number 1910.333 specifically addresses Standards for Work Practices and references NFPA 70E. OSHA 29CFR 1910.335 (a) (1)(i) requires the use of protective equipment when working where a potential electrical hazard exists and 29CFR 1910.132(d)(1) which requires the employer assess the workplace for hazards and the need for personal protective equipment.

OSHA compliance is required by any plant building or facility.

What is an arc flash hazard?

Arc Flash Accident

 

Think of an arc flash as a short circuit through the air. In an arc flash incident, an enormous amount of concentrated radiant energy  explodes outward from electrical equipment.

The explosion creates pressure waves and a superheated ball of gas that can severely burn a worker’s body and melt metal. The pressure waves can also propel loose material like molten metal, pieces of damaged equipment, tools and other objects, through the air.

In general, arc flash incidents are highly improbable on systems operating at less than 240 volts phase to phase (120V to ground) when fed by less than a 120 KVA transformer 120 volts does not provide sufficient energy to cause an arc flash hazard. Most 480V electrical services have sufficient capacity to cause an arc flash hazard. Medium-voltage equipment (above 600V) is higher energy and therefore a higher arc flash hazard.

 

2. The National Fire Protection Association (NFPA) Standard 70 - 2002 “The National Electrical Code” (NEC) contains requirements for warning labels.

3. NFPA 70E provides guidance on implementing appropriate work practices that are required to safeguard workers from injury while working on or near exposed Label.electrical conductors or circuit parts that could become energized. Part II 2-1.3.3 regarding Arc Flash Analysis states that a “Flash Hazard Analysis shall be done before a person approaches any exposed electrical conductor

or circuit part that has not been placed in an electrical safe work condition”. This Arc Flash Hazard Analysis must be done to determine the level of Personal Protection Equipment PPE that a worker must use, and the Arc Flash Boundary in inches along with the incident energy found at each location. Each panel must be marked with an ANSI z535 approved Arc Flash Warning

4. The Institute of Electronics and Electrical Engineers (IEEE) 1584 – 2002 Guide to Performing Arc-Flash Hazard Calculations.

IEEE 1584-2002 was developed to help protect people from arc-flash hazard dangers.

The predicted arc current and incident energy are used in selecting appropriate overcurrent protective devices and personal protective equipment, as well as defining safe working distance. Since the magnitude of the arc current is inherently linked with the degree of arc hazard, the arc is examined as a circuit parameter.

Furthermore, since estimation are often useful, simple equations for predicting ballpark arc current, arc power, and incident energy values and probable ranges are presented in this work.

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HOW SENVA SENSORS REDUCE ARC FLASH HAZARD

Senva Sensors

Avoiding calibration in an energized enclosure is the best way to avoid arc flash when working with current sensors. Senva offers two models--Autoset and Preset—which both address this application issue. 

Autosettm self-calibrates after installation using Senva’s 24sensetm technology which adapts to system changes, such as air balancing.

Presettm uses a unique, patent pending, scaled adjustment which is set to the motor FLA.  It is priced comparably  to manually adjusted sensors, but saves up to $30 per point, because there is no need to return to the site to calibrate

Get all the facts at Senvainc.com.

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