- February 16, 2011
Automation.com, February 2011
Technicians working on hazardous equipment and high-voltage circuits deserve every advantage to complete electrical test and measurement jobs safely. New test tools provide new ways to work safely and reduce exposure to electrical shock.
Technicians working on hazardous equipment and high-voltage circuits deserve every advantage to complete their electrical test and measurement jobs safely. Now, new test tools are engineered to give electricians and maintenance technicians new ways to work safely and reduce their exposure to electrical shock.
Industrial and commercial electricians often work in 480 volt electrical environments that pack enormous transient surge potential—and pose a significant threat of arc flash and shock. New test tools meet— and exceed—tough international standards for safe use in such environments. And some go even farther, by enabling technicians who must test live circuits to do their jobs at a distance from electrically hazardous installations.
What Safety Ratings Mean
For electrical workplace safety in the US, the key standard is National Fire Protection Association (NFPA) 70E, Standard for Electrical Safety in the Workplace. The US Occupational Safety and Health Administration (OSHA) refers to NFPA 70E for electrical safety.
The preferred way to work on hazardous electrical circuits is with the power off. Equipment that could be turned on must be locked out and tagged. But some tests, such as the current tests that clamp meters perform, simply aren’t possible unless circuits are live.
As the electrical work environment becomes more hazardous, the need for arc flash, electrical transient and electrical shock protection increases. For situations when a location-specific arc flash hazard analysis is not available, NFPA 70E defines the arc flash protection boundary for equipment with voltage levels between 50 V and 600 V at four feet. (See NFPA 70E section 130.3 (A) (1) for full details.) The standard names a wide variety of electrical maintenance tasks and assigns each a hazard/risk category of 0 to 4. The standard also details the kind of personal protective equipment (PPE) that must be worn when working in the various hazard/risk categories.
The NFPA standard categorizes test equipment as PPE and requires that test equipment be rated and designed for the circuits and environments where it will be used. To clarify what this means, the 2009 Edition of NFPA 70E cites American National Standards Institute (ANSI)/ISA- 61010-1 (82.02.01)/UL 61010-1, the standard first established as International Electrotechnical Commission (IEC) 61010.
These measurement categories (CAT) listed in the standards cover systems of 1000 volts or less, including 480-volt and 600-volt, three-phase circuits. They define the danger of transient voltage spikes and electrical arc flash and differentiate the severity by location, voltage level and potential for harm. ANSI, the Canadian Standards Association (CSA) and IEC define four measurement categories.
- CAT IV - Is applicable to test and measuring circuits connected at the source of the building’s low-voltage MAINS installation.
- CAT III - Is applicable to test and measuring circuits connected to the distribution part of the building’s low-voltage MAINS installation.
- CAT II - Is applicable to test and measuring circuits connected directly to utilization points (socket outlets and similar points) of the low-voltage MAINS installation.
- CAT I - defines non-CAT rated products that are not intended to be directly connected to the MAINS supply.
Some installed equipment may include multiple categories. A motor drive panel, for example, may be CAT III on the 480-volt power side, and CAT I on the control side.
A higher CAT number refers to an electrical environment with higher power available and the potential for higher-energy transients. A test tool designed to a CAT III standard can resist higher energy transients than one designed to CAT II standards. Within a category, a higher voltage rating denotes a higher transient withstand rating. For instance a CAT III-1000 V test tool has superior protection compared to a CAT III-600 V rated tool.
The new Fluke 381, 376, 375 and 374 current clamps and iFlex current probes are rated for use in measurement category IV environments (CAT IV 600V, CAT III 1000 V) as defined by safety standards in the US, Canada and Europe. The detachable display of the new Fluke 381 Clamp Meter enables technicians to see measurements remotely—up to 33 feet away from the equipment they are testing. They can even see readings when the test circuit is enclosed in an equipment cabinet.
The new Fluke ScopeMeter® 190 Series II handheld portable oscilloscopes are the first four-channel scopes designed for harsh industrial environments. Not only are they rated as dust and drip-proof, but they are also the first hand held oscilloscopes safety rated for CAT III 1000 V / CAT IV 600 V environments.
A New Family of Safety-Rated Test Tools
All members of the new Fluke clamp meter family have a CAT IV rating. They are designed to provide flexibility, performance and safety in the most challenging industrial conditions. The four-channel Fluke ScopeMeter® 190 Series II portable oscilloscope is also designed to tough it out on the shop floor, while providing CAT IV-600 V protection.
For More Information
Fluke is focused on incorporating safety into test tool design. The company also offers an extensive array of electrical safety education and training materials, available without charge, through the Fluke Electrical Safety Education Program. Visit the Fluke safety training website for more information.
Founded in 1948, Fluke Corporation is the world leader in compact, professional electronic test tools. Fluke tools deliver the testing and troubleshooting capabilities that are critical to keep commerce and industry running smoothly. Fluke customers are technicians, engineers, electricians, metrologists and building diagnostic professionals who install, troubleshoot and manage industrial, electrical and electronic equipment and calibration processes for quality control and building restoration. For more information, visit the Fluke Web site at http://www.fluke.com
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