The Basics of Enhancing Safety with Electrical Control Panels
Electricity is a major safety hazard in the workplace, according to the U.S. Office of Compliance, which states that 400 employees were unable to work for 31 days or more due to electricity exposure injuries, 1,970 occupational injuries resulted from exposure to electricity and 154 fatalities occurred due to exposure to electricity in the workplace in 2018 (the most current year for which statistics exist).
Obviously, a lot of machinery used on the factory floor is driven by electric power, which can make it seem next to impossible to prevent electricity-related workplace injuries. However, while electrical control panels are often simply viewed as a place to keep electrical components organized when properly and thoughtfully designed, they can help improve safety and reduce instances of both electricity-related and other types of workplace injuries. While it’s understood that electrical control panels provide the basic preventive measures such as keeping workers from getting too close to electrical components and housing switches that will cut off power to a machine in the event of an electrical emergency, they often include additional features that further enhance workplace safety.
Electrical Control Panels Reduce Electrical Hazards
To fully understand the ways in which electrical control panels can improve safety in the facility, it’s helpful to know what is typically contained within them and how these components are designed with safety in mind.
The enclosure itself is designed to keep workers from coming into contact with the electrical components housed inside and to protect these components from the outside environment which may include moisture, dust, and debris, which could damage the components and create shock, fire, and explosion hazards.
Within the enclosure are many of the components you’d expect to see such as the main circuit breaker, which allows the electrical control panel to be manually connected or disconnected from the main power line during maintenance or emergencies and can automatically disconnect the panel from the power system in the event of a power line fault current. Branch circuit breakers can be used to intentionally connect or disconnect individual machinery from the power line and will also automatically disconnect in the event of a power line current fault. Some types may also protect against thermal heat to prevent short-circuiting.
Step-down transformers may be included to reduce incoming voltage to the amount that is required to safely run the system or machine at the levels for which the equipment is designed. These are often employed when the voltage comes in at a higher rate than some of the machines or systems require or when multiple levels of voltages are required if a variety of electrical equipment is controlled by the same panel. Terminal blocks may be found in heavy-duty electrical control panels where multiple power sources or voltage levels are required.
Programmable Logic Controllers (PLCs) can be found inside control panels and operate the electrical system for the machine or system based on preset inputs. PLCs work in conjunction with sensing devices such as proximity switches and sensors that provide feedback to the PLC and allow it to change the output to ensure that the system stays within efficiency and safety limits. Safety-minded PLCs and related drives often have the capability to monitor themselves for failure, further enhancing safety.
When an electrical control panel organizes the components of complex machines or systems, a Human Machine Interface may be included to provide operators with a view into the equipment and its operation so they may understand the situation, make appropriate decisions and input control functions to maintain safety and control over the machine and its power system.
Network switches control the connectivity and communication between the PLC and the equipment to which it provides logic and commands. Relays are protective devices that connect and disconnect electrical equipment from the power source. They provide the operator with the ability to control the power connected to electrical equipment such as lights, fans, motors and emergency stop circuits.
Push buttons are also included in electrical control panels. They may be used by operators to control different operations or individual machines. There is usually an emergency stop button and a reset button within a control panel for safety purposes.
Keep in mind that just having safety-minded components isn’t enough, proper design and layout of these and other essential components within an electrical panel is necessary in order to provide the safest method of power distribution and control. Following NFPA 70 National Electrical Control guidelines is the best way to ensure safety within the electrical control panel.
Control Panels Go Beyond Electrical Safety
Keeping voltage and power in check to reduce the chances of electrical-related workplace injury is just one way that control panels can enhance safety in manufacturing operations. Additional safety benefits exist. For instance, a machine’s control panel may employ two-hand control systems, which are used with a two-hand control monitoring relay that requires an operator to use both hands at the same time when working with a hazardous machine, forcing operators to keep their hands out of harm’s way. Similarly, including controls and switches for a specific machine within a control panel may prevent pinch-point injuries because operators aren’t reaching over or around the equipment to operate it.
Safety sensors, such as those found in light curtains, safety mats, and area sensors, may also be tied into machine or system control panels to stop equipment when an operator enters an unsafe area, preventing workplace injuries. Non-contact or interlock safety switches can also be employed to ensure that workers can’t bypass these safety guards and sensors as these switches and sensors will detect when a system is removed or bypassed and stop power to the machine or system.
General Safety Tips to Prevent Electrical Injuries
In addition to operating equipment and systems through a properly designed electrical control panel, it’s important to ensure that guards, shields, and other safety devices are used on the components and assemblies within an electrical panel to prevent accidental contact with energized components. Further, electrical components should be laid out in a manner that allows enough room to work within the panel enclosure and provides adequate airflow to prevent overheating. Proper lock-out/tag-out equipment and practices should always be used when working on electrically powered equipment and guidelines regarding the use of the correct personal protective equipment (PPE) should always be followed by employees and enforced by management to ensure that workers are wearing the right PPE for the job.
For more information on how to design the safest electrical control panel and how to incorporate safety devices, such as light curtains and safety sensors, within it, please get in touch with an expert at John Henry Foster.