| In the late 1880s, a young boy was electrocuted | | | | 6. Personal Protection -Reducing risks of working |
| when he accidentally touched an unlabeled, | | | | on live voltage. |
| energized telegraph wire. That incident ignited an | | | | Electrical workers are exposed to the greatest |
| inventor by the name of Harold Pitney Brown to | | | | risks at the lower levels of the RCH. Recognizing |
| make an impassioned plea in a New York Post | | | | that these 'residual risks' are present; the NFPA |
| editorial to limit telegraph transmissions to what he | | | | 70e tells workers how to perform their work |
| considered a safer level of 300 Volts. | | | | safely in spite of these risks. In fact a large |
| Perhaps Harold thought that limiting electrical | | | | portion of the NFPA 70e details how to best |
| transmissions to levels of 300 Volts or less would | | | | manage these risks through Awareness, |
| provide instant electrical safety. With over 120 | | | | Administration, and Personal Protection. On the |
| years of hindsight, we view things much | | | | other hand, the greatest opportunity for risk |
| differently today. Yet, Harold stumbled across | | | | reduction comes by focusing in the upper part of |
| two important concepts. The notion of "300 | | | | the RCH. Huge improvements in electrical safety |
| Volts" is a technical discussion about the laws of | | | | will come by Eliminating Substituting, and |
| electrical energy (Ohm's Law, etc) that lends | | | | Engineering solutions that manage electrical energy |
| understanding to how electrical energy can kill or | | | | exposure. |
| maim. On the other hand, the term "safe" reflects | | | | The Department of Energy (DOE) |
| a working knowledge of the fundamental principles | | | | For better insight into the RCH process, let's look |
| of safety. Our challenge is to combine our | | | | at a 2005 Department of Energy report on their |
| technical understanding of electricity with the | | | | electrical safety record. This report cited six |
| principles of safety to ensure electrical safety is | | | | reasons for their 14.1 electrical incidents per |
| both practical and effective. The better we | | | | month. |
| understand both concepts the greater the | | | | Within this DOE report, "hazard identification" |
| likelihood we will have to improve the status quo. | | | | [Table 1] stood out as an administrative control |
| The Risk Control Hierarchy (RCH) does an | | | | issue resulting in numerous electrical incidents. The |
| excellent job in blending these two key concepts. | | | | solution was to get tougher administrators or look |
| Risk Control Hierarchy | | | | for improvements higher up in the RCH. Right |
| The heartbeat of safety is the Risk Control | | | | above Administrative Controls (see Figure 1) we |
| Hierarchy (RCH), which is found in Appendix G of | | | | learn that increasing employee's awareness of |
| the ANSI Z10 Standard. The RCH helps us | | | | electrical hazards will reduce these types of |
| prioritize safety initiatives from least effective to | | | | incidents. A potential solution is to label and mark |
| most effective. For example, will you be safer | | | | all voltage sources (hazards) feeding the electrical |
| wearing a helmet while riding a motorcycle or by | | | | system. Voltage indicators and voltage portals |
| selling it altogether? Obviously, selling the | | | | wired to each voltage source provides two |
| motorcycle eliminates the risk of an accident, | | | | benefits: It identifies the voltage source and |
| while wearing a helmet offers protection to your | | | | provides a means to check the status of that |
| head from the risk of a head injury during an | | | | voltage source without exposure to voltage. |
| accident. The RCH works by helping us rank risk | | | | Apply the same process to "LO/TO violations". |
| reduction measures from most effective to least | | | | CAUSES OF INCIDENTS PRESENT RCH |
| effective as per below: | | | | PRINCIPLE INCREASED RISK REDUCTION RCH |
| 1.) Eliminating the risk. | | | | PRINCIPLE Lack of hazard identification. |
| 2.) Substituting a lesser risk. | | | | ADMINISTRATIVE Properly administrating NFPA |
| 3.) Engineering around risk. | | | | 70e requires all electrical enclosures to have |
| 4.) Awareness of every risk. | | | | warning labels with incident energy level (calories). |
| 5.) Administrate and regulate behavior around risk. | | | | AWARENESS /ELIMINATION Marking all energy |
| 6.) Protect workers while exposed to risk. | | | | sources on the panel exterior provides personnel |
| Note that each step above is equally important, | | | | with simple yet safe hazard identification. |
| yet not equally effective in protecting workers. | | | | LO/TO violations including shortcuts or lack of |
| Eliminating a risk is the most effective way to | | | | energy verification |
| keep workers safe while protection from a risk | | | | ADMINISTRATIVE Can the LO/TO procedure be |
| by using Personal Protection Equipment (PPE) is | | | | rewritten to reduce exposure to voltage? |
| least effective. There have been great | | | | ELIMINATION /SUBSTITUTION Thru-door voltage |
| improvements in the design of PPE, but its | | | | pre-checking 'eliminates' all exposure to voltage |
| primary purpose is keeping workers alive - not | | | | for mechanical LO/TO* and provide significant risk |
| 100% safe. | | | | reduction for Electrical LO/TO. |
| Safety and Risk | | | | Reducing electrical energy to Cat 0/1 will greatly |
| Risk, which is defined as exposure to a hazard, is | | | | reduce the potential arc flash energy |
| two-pronged. There is the probability of exposure | | | | SUBSTITUTION Lowering the arc flash energy |
| and severity of potential injury. For example, a | | | | effectively 'substitutes' for a lower risk for a |
| 120V outlet is a greater risk than a 13.8KV | | | | higher risk. |
| switchgear line-up because more people are | | | | Elimination: The Hall of Fame of Safety |
| exposed to the 120V outlet. Since risk is | | | | We can enter the Electrical Safety Hall of Fame |
| exposure to hazards, then safety is the reduction | | | | by finding ways to eliminate voltage exposure. |
| and management of risk. The management | | | | Here are a few practical examples that can be |
| responsibility of an electrical safety program | | | | implemented today:o Mechanical Lock-out Tag-out |
| typically falls to an electrical engineer because he | | | | [LOTO]: LOTO procedures requiring electricians to |
| or she understands electricity. In our modern | | | | verify zero energy before performing mechanical |
| world we can never eliminate the risk, but are | | | | maintenance needlessly exposes workers to |
| very good at finding new ways to reduce risk. | | | | voltage. Since all voltages do not create |
| Another way to look at risk is the chart (Figure 2) | | | | mechanical motion, thru-door voltage checking |
| developed by Ray Jones which shows the | | | | devices as part of a mechanical LOTO procedure |
| relationship between the worker and the safety | | | | will eliminate voltage exposure (see Appendix B).o |
| infrastructure above him. A worker performing | | | | Why open a control panel? What maintenance |
| tasks must make many complex and specific the | | | | functions can be moved to the outside of the |
| decisions that affect his safety. In the case of | | | | panel? Thru-door data access ports are becoming |
| electrical safety, energy isolation is very personal | | | | commonplace because they allow programming |
| for electricians facing deadly electrical energy | | | | with the panel door closed (Figure 3). A more |
| every time they open a panel. By the time they | | | | recent example is an unmanaged Ethernet switch |
| touch electricity, it's too late. | | | | mounted outside the panel. This unique device |
| Zero Energy Verification--Is There Voltage? | | | | allows full thru-door access for a worker to |
| Electrical accidents are impossible without electrical | | | | troubleshoot and reset the Ethernet switch (Figure |
| energy. If an electrician comes into direct contact | | | | 4). What other devices can be re-engineered |
| with electrical energy, there is a 5% fatality rate. | | | | around thru-door electrical safety? Perhaps putting |
| Shocks and burns comprise the remaining 95%. | | | | certain branch circuit breakers on the outside of |
| The NFPA 70e is very specific on how to isolate | | | | the panel is a good application?o Control Panel |
| electrical energy. First, all voltage sources must be | | | | Design: Provide a physical separation between the |
| located and labeled. Multiple voltage sources are | | | | power and control compartments within an |
| commonplace today due to the proliferation of | | | | enclosure may become a standard. Voltages |
| back-up generators and UPS's. Next, voltage | | | | under 50 volts are considered safe, so reducing |
| testing devices must be validated using the | | | | the control power to 24VDC makes the control |
| LIVE-DEAD-LIVE procedure. Additionally, the | | | | power section safe to work on while it is |
| voltage tester must also physically contact the | | | | energized. |
| voltage and must verify each phase voltage to | | | | These above examples are only 'scratching the |
| ground. | | | | surface', so I challenge you to find ways to |
| The RCH and Electrical Safety | | | | eliminate voltage exposure. |
| How does the RCH apply to electrical safety? | | | | Conclusion |
| 1. Elimination -Removing all electrical energy | | | | When safety works perfectly, nothing happens! |
| exposure. | | | | When there is an incident or a close call the RCH |
| 2. Substitution -Lowering the electrical energy | | | | should be an inspiration to find a better way. By |
| exposure. | | | | applying the RCH principles to electrical safety |
| 3. Engineering Controls -Reinventing ways to | | | | risks, it will open our eyes to see more practical |
| control electrical energy exposure. | | | | ways to reduce those risks. Perhaps, we would |
| 4. Awareness -Revealing and labeling all sources of | | | | expend more resources finding electrical safety |
| electrical energy. | | | | solutions that will provide both higher safety and |
| 5. Administrative Controls -Regulations that teach | | | | productivity dividends. |
| personnel safety around electrical energy. | | | | |