By: Sean Silvey, Fluke Corporation
Plant safety is much more than just tasks on a checklist. It requires a commitment from every employee—from management to line workers—to maintain a culture of safety in all aspects of the operation. Over time, interpretations of certain safety standards can stray from the original intent creating some myths about how best to meet safety requirements.
Myth #1: “Inconvenient” is the same as “infeasible” when it comes to de-energizing equipment for maintenance
There’s no doubt that it is almost always inconvenient to shut down power unexpectedly to work on a piece of equipment. But that doesn’t mean it’s infeasible. The European Agency for Safety and Health at Work (EU-OSHA), national equivalents such as the Health and Safety Executive (HSE) in the UK and the DGUV (German Statutory Accident Insurance) as well as other local authorities, permit working on an energized circuit only under certain conditions, including when it’s “infeasible” to shut down power due to increased hazard. However, there is a tendency to allow employees to work on live circuits just because it’s “inconvenient” to shut down power. This adds unnecessary risk that often leads to accidents.
In situations where it actually is infeasible to shut down the power, only electricians and technicians qualified to work on energized systems should perform the work. They should take all precautions, including wearing proper personal protective equipment (PPE) and using tools certified according to applicable safety standards (e.g., EN 60900) for the conditions they encounter.
Myth #2: The more PPE the better
Whether to wear PPE, and how much to wear, are not personal decisions. A component can fail at any time. Perfectly good breakers can fail suddenly during troubleshooting. If an arc flash occurs while simply opening a cabinet, wearing the correct PPE can mean the difference between surviving or not. Electricians and technicians must follow the detailed PPE requirements in the European Standard EN 50110 “Operation of electrical installations”, which defines electrical safety in the workplace. However, requiring workers to wear PPE rated for a much higher hazard level than the environment calls for will not necessarily make them safer.
“More PPE is not necessarily better,” says Kevin Taulbee, Electrical Engineer and Safety Trainer at Power Studies, Inc. “Having the right PPE is what counts. Performing proper job hazard analysis is important for equipping workers with the correct PPE. Too many people just go out and purchase arc flash moon suits and thick, high voltage linemen gloves for their in-house maintenance and electrical workers. Class 2 electrical gloves aren’t necessary if they never get into anything over 480 volts and they offer much less dexterity. As a result, an electrician may be more likely to drop a tool or lead when working in an energized panel.”
In addition to choosing the correct PPE, it is possible to choose handheld test tools that have been designed to make it easier to push buttons and turn dials when wearing heavy gloves. It is also possible to reduce the amount of PPE required in some instances by equipping workers with non-contact infrared (IR) tools such as thermal imaging cameras, IR thermometers, and wireless monitoring sensors. These tools allow workers to capture data from outside the arc flash zone. Alleviating the need to work inside an arc flash boundary, particularly when switching or troubleshooting, will increase the overall level of safety for workers.
Myth #3: All test leads and fuses are created equal
Often technicians regard test leads and fuses as basic commodity components without giving quality much thought. Regardless of the quality of the multimeter, it’s only as safe as the test leads used with it and the fuses inside. These components provide critical protection against power surges and voltage spikes that can cause serious injury to the user.
Choosing the right test leads
The primary job for test leads is to connect the digital multimeter to the equipment being tested, but they also provide a first line of defense against electrocution. Test leads that are poorly made, worn, or aren’t rated for the job at hand, can produce inaccurate readings and may pose a serious shock hazard if touched to the wrong wire. When choosing test leads look for:
- High quality materials and rugged construction
- Rating for the appropriate measurement category as specified by EN 61010 and the voltage level of the application. The category (CAT) rating on test leads and accessories should match or exceed the category of the DMM.
- Exposed metal that matches the energy potential of a specific measurement.
- Retractable probes, probe tip covers, or probes with shorter tips to avoid an inadvertent short circuit.
Pick high quality replacement fuses
Today’s safety standards require digital multimeters to include special high-energy fuses that are designed to keep the energy generated by an electrical short, within the fuse enclosure. This protects the user from electric shock and burns. When it’s time to replace fuses always choose the high energy fuses approved by the meter’s manufacturer. Cheaper generic replacement fuses increase the risk of serious injury.
Myth #4: The only way to accurately measure live voltage is with test lead contact.
In the past, attaching test lead probes or alligator clips directly to electrical conductors was the best way to get accurate results. However, this requires metal-to-metal contact, which increases the risk of arc flash and potential harm to both the person doing the measuring and the equipment being measured.
Recently a new technology was introduced that detects and measures voltage without metal-to-metal contact. This technology isolates the measurement tool from the voltage source under test. To measure voltage, electricians and technicians just slide a single conducting wire into the open fork of the handheld test tool. Since they aren’t exposed to contact points with live voltage, the risk of electrical shock and arc flash is reduced.
The myths listed above represent just a small sampling of the safety issues to be considered when working on energized equipment. The best way for a facility to ensure that employees fully understand and follow all the relevant electrical safety regulations is to develop and maintain a solid safety culture based on the needs and environment of that specific facility.