Several myths about electricity are ubiquitous. Plant safety is much more than just some tasks on a checklist. It requires commitment from every employee, from management to line workers, to maintain a culture of safety in all aspects of operations. Over time, interpretations of certain safety standards may differ from the original intent, creating myths about how best to meet safety requirements.
Myth 1: “Awkward” is the same as “unfeasible” when it comes to de-energising equipment for maintenance
Of course, it is almost never convenient when the power has to be turned off unexpectedly to work on a piece of equipment. But that does not mean it is not feasible. 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, only allow working on a live circuit under certain circumstances. This includes when it is ‘unfeasible’ to switch off the power because of increased risk. However, there is a tendency to allow workers to work on live circuits just because it is “inconvenient” to switch off the power. This leads to unnecessary risks that often lead to accidents.
In situations where it is impossible to switch off the power, only electricians and technicians qualified to work on live systems should carry out the work. They should take all precautionary measures, including wearing the appropriate personal protective equipment (PPE) and using tools certified according to the applicable safety standards (e.g. EN 60900) for the relevant conditions.
Myth 2: The more personal protective equipment, the better
Whether to wear personal protective equipment, and how much, is not a matter of personal choice. A component can fail at any time. Perfectly working circuit breakers can suddenly malfunction while troubleshooting. If an arc occurs just by opening a cabinet, wearing the right personal protective equipment can mean the difference between life and death. Electricians and technicians should follow the detailed personal protective equipment requirements in European standard EN 50110 “Operation of electrical installations”, which defines electrical safety in the workplace. However, requiring workers to wear personal protective equipment classified for a much higher risk level than required by the environment does not necessarily make them better protected.
“More personal protective equipment is not necessarily better,” says Kevin Taulbee, Electrical Engineer and Safety Trainer at Power Studies, Inc. “It's all about using the right personal protective equipment. Doing a proper hazard analysis before the job is important to equip employees with the right PPE. Too many people just buy arc-resistant moon suits and thick high-voltage gloves for cable workers for their in-house maintenance workers and electricians. Class 2 electrical gloves are not necessary if they never come into contact with a voltage of more than 480 V, and they offer much less freedom of movement. As a result, an electrician is more likely to drop tools or test leads when working on a live panel.”
In addition to choosing the right PPE, it is possible to choose hand tools designed to make it easier to operate buttons and dials when heavy gloves are worn. It is also possible to reduce the number of personal protective equipment required in some cases by equipping workers with non-contact infrared instruments (IR instruments), such as thermal imaging cameras, infrared thermometers and wireless monitoring sensors. These tools allow workers to capture data from outside the arc zone. Removing the need to work within an arc boundary, especially when switching or troubleshooting, increases the overall level of safety for workers.
Myth 3: All test leads and fuses are the same
Often technicians consider test leads and fuses as basic components without paying much attention to quality. Regardless of the quality of the multimeter, it is only as safe as the test leads used and the fuses inside. These components provide essential protection against current and voltage spikes that can cause serious injury to the user.
Choosing the right test leads
The main task of test leads is to connect the digital multimeter to the device to be tested, but they are also a first line of defence against electrocution. Measurement leads that are poorly made, worn out or not suitable for the work to be performed can produce inaccurate readings and pose a serious shock hazard if touched with the wrong wire. When choosing measurement leads, pay attention to the following:
- High-quality materials and robust construction
- Classification for the relevant measurement category as specified in EN 61010 and the voltage level of the application. The category (CAT) of the measuring leads and accessories must match or exceed the category of the DMM.
- Exposed metal corresponding to the energy potential of a specific measurement.
- Retractable measuring pins, measuring pin sleeves or measuring pins with shorter ends to prevent accidental short circuits.
Choose high-quality replacement fuses
Current safety standards require that digital multimeters are equipped with special high-power fuses designed to keep the energy generated by an electrical short circuit within the fuse housing. This protects the user from electric shock and burns. When it is time to replace fuses, always choose high-power fuses approved by the meter manufacturer. Cheaper generic replacement fuses increase the risk of serious injury.
Myth 4: The only way to accurately measure voltage is to make contact with a test lead.
In the past, connecting test lead probes or crocodile clips directly to electrical conductors was the best way to obtain accurate results. However, this requires metal-to-metal contact, which increases the risk of arcing and possible injury to the person measuring or damage to the equipment being measured.
Recently, a novel technology introduced that detects and measures voltage without metal-to-metal contact. This technology isolates the measuring instrument from the voltage source under test. To measure voltage, electricians and technicians slide only one conductive wire into the open fork of the hand-held measuring instrument. Because they are not exposed to live contact points, there is less risk of electric shock and arcing.
The myths mentioned above are just a small selection of the safety issues that should be considered when working on live equipment. The best way for a facility to ensure that employees fully understand and comply with all relevant electrical safety regulations is to develop and maintain a solid safety culture based on the needs and environment of that particular facility.
