![]() If you’re farther than the indicated distance, you’re fine. No one is going to take out their metal tape measure and try to be as accurate as possible. Table 1 illustrates Table 130.4(D)(a) Table 2 illustrates 130.4(D)(b).īear in mind that these distances are approximated in the field. In industrial facilities, this often must be done by the local utility. Another point to remember is that only qualified persons should approach overhead conductors unless they have been locked out/tagged and grounded. Equipment tends to bob and sway, especially if the wind is blowing or the lift is extended. It is also for when mechanical equipment is approaching an exposed conductor, movable or otherwise. Column 2 is for exposed movable conductors, such as overhead power lines. One key point to remember is that this table has two columns for the limited approach boundary. The shock approach boundaries are easy enough to interpret from Table 130.4(D)(a) for AC voltages and 130.4(D)(b) for DC voltages. More detailed information on the hierarchy of risk control methods is found in Informative Annex F. Not everyone catches that it’s just a normal day on the job - but it is not normal. The fact that equipment requires troubleshooting indicates it’s at risk of failure. Troubleshooting increases the shock risk because if the equipment was in normal operating condition, per Section 110.2(A)(4), troubleshooting would not be necessary the risk of arc flash also increases. It would be unsafe (and not too smart) to troubleshoot energized electrical conductors and circuit parts without using PPE. The other risk control methods listed in 110.1(H)(3) should be incorporated to the degree possible. Elimination is always the first choice PPE is the last, although using appropriate PPE is often unavoidable. Due to issues that arose using standards from American National Standards Institute (ANSI) and American Industrial Hygiene Association (AIHA) in this particular application, it won’t be carried over into the 2021 edition, although its intent will be. A quick look at that section shows use of PPE as the lowest priority, while placing the equipment in an electrically safe work condition (elimination) is highest. 130.4(A) states the purposes of performing a shock risk assessment, while 130.4(B) provides the needed information concerning “additional protective measures” as provided in Section 110.1(H)(3). “N” indicates that a new section was added. ![]() (3) The personal and other protective equipment required by this standard to protect against the shock hazard (1) The voltage to which personnel will be exposed When the additional protective measures include the use of PPE, the following shall be determined: If additional protective measures are required, they shall be selected and implemented according to the hierarchy of risk control identified in 110.1(H). (3) To determine if additional protective measures are required, including the use of PPE (2) To estimate the likelihood of occurrence of injury or damage to health and the potential severity of injury or damage to health A shock risk assessment shall be performed: But before the tables, Section 130.4 Shock Risk Assessment states: In NFPA 70E-2018, Article 130 Section 130.4 outlines the shock protection boundaries. Now, this was an old paper, but the percentages even now tell a real story about the risk involved in dealing with lower voltages.įigure 1: Lethal Voltages at an Industrial Facility What is very surprising to most people is that 100–250 V is right next to it at 39%. It is also not surprising that 250–600 V (mostly 480 V) is the largest percentage of fatalities at 45%. ![]() Since these were industrial sites and not utilities, it’s not surprising to see that the over-600 V range is only 11% of the fatalities. DuPont included Figure 1, which was the result of a study done at their facilities. Somewhere in the 1999–2002 range, an IEEE Electrical Safety Workshop presentation by Lanny Floyd and Danny Liggett of E.I. After all, what electrician or technician hasn’t been shocked at one time or another and just received a slight jolt, maybe a sting - and you look around to make certain no one was watching? We tend to think of low-voltage shocks as more of a nuisance then a real threat, but that is wrong-headed thinking. Arc flash gets the most attention because of the serious injuries caused by an arc flash, not to mention the visual and audible results, which tend to be more impressive than a shock. Shock remains the number-one cause of electrical fatalities and has been for several years. Until that release, the current edition must be referenced. The 2021 edition will be released to the public in late September or early October, first in pdf form, then as a printed document. The 2018 edition of NFPA 70E is still active, even though many people are looking forward to a new edition in 2021.
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