Codes and regulations: Electrical Controls’ Dirty Little Secret: We Don’t Follow NFPA Rules

Of course safety is important, but most don’t follow NFPA 70e safety rules for working on an energized electrical panel. Risky? Yes. Unsafe? No, according to this system integrator. Perhaps industrial control panels need their own arc flash standard. (Do you follow the rules when working on control panels? Link to anonymous survey results. See related articles.)

10/17/2011


Most of us in the industrial control business have a dirty little secret. We don’t follow the rules (NFPA 70E) for working on an energized electrical panel.

Let me be clear. Electricity is VERY dangerous. I’ve read the statistics that there are one to two arc flash deaths and many more injuries every day. What I don’t know is how many accidents involve a guy in a backhoe pulling up an unmarked utility line at an older industrial site, a contractor replacing a fluorescent lighting ballast on an energy-saving project, or a plant electrician stabbing in a new circuit breaker in a distribution panel.

A system integrator suggests that new rules are needed for working on control panels with less than 600 V ac with proper fused power disconnect. Does a qualified person really need PPE when programming with a PC? Note that an electrical distribution panelI’ve sat in my chair in front of an open control panel, programming a PLC with my laptop—for hours at a time. I’ve opened a live panel and changed a speed setting on a VFD. Have I taken a risk? Yes. Am I being unsafe? No. I work on industrial control panels designed with finger-safe components, fused main disconnects, and ac power segregated from low-voltage dc power.

I work on industrial control panels, not electrical distribution panels or motor control centers. I use IEC, finger-safe (IP20) components. This dramatically reduces the risk of accidental contact to live electrical components. Older panels with open components—NEMA starters, NEMA disconnects, fuse holders—still make me nervous even when de-energized.

Do you use electrical PPE when working on non-high-voltage problems (such as programming an ac variable frequency drive)?I use Class J or CC fuses in my main power disconnect along with fuses on my motors and transformers. This dramatically reduces the dangers from arc flash versus circuit breakers. The approach distance is much lower and the exposure time shorter when using fused components. For most panels I use a NFPA 79-type disconnect. It has a big, red handle that allows power to be turned off and on without using a metal adjustable wrench that could accidentally cause a short. This handle has made it much more likely for the panel power to be turned off to work on ac circuits since it’s so easy and doesn’t require a tool. A typical two-door panel I work on has an AC section on the right side with VFD, motors starters, and fuse holders. The left side of the panel has a PLC, safety relays, and dc power supplies. I program the VFDs soon after the power is applied to the panel for the first time. After that, I rarely go near the ac side of the panel. Programming ports with an Ethernet connection and a GFCI receptacle are provided for any panel that has a PLC or a vision camera. After start-up, most troubleshooting can be done with a laptop without having to open up the enclosure.

So am I taking a risk working on my control panels? Of course I am. I take a risk every day when I hop in my car to drive to work or, even worse, when I put gas in my car. Every year, a bunch of guys go out on boats in the Bering Sea and risk their lives for crab legs. Don’t even get me started on those guys sawing down trees and pulling them up hills with jury-rigged equipment. Then for a vacation watch performers jumping and flying all over the stages in a Cirque show in Vegas—they jump into a pool of water that was a solid floor just a few seconds earlier. These work activities are far more dangerous than anything I do inside of an electrical control panel. In the workplace you are more likely to be killed by a motor vehicle, be a victim of an assault or homicide, get struck by object, or fall to your death. Less than 10% of workplace deaths are caused by electrocution.

Industrial control panels designed with finger-safe components, fused main disconnects, and ac power segregated from low-voltage dc power can decrease risk.Here are a few more questions to ask yourself: Should I put on flame-resistant clothes, gloves, and other electrical personal protective equipment (PPE) to plug in my 220 V ac plug for my electrical dryer? Should I let my kids plug in laptops, cell phone chargers, and the toaster into a 120 V ac outlet every single day without any protection? I must be a horrible father and a hazard to everyone who works near me. If safety is the number-one priority and everyone is so concerned with my safety, shouldn’t I always wear a full 40 cal/cm² hood along with HRC 4 pants, coat, and 1,000-V insulated rubber gloves—just to be on the safe side?

Here are my suggested PPE (not the NFPA 70e rules) for working on control panels with less than 600 V ac with proper fused power disconnect (see related photos):

  • The PPE label on a control panel would indicate that the panel has been designed and built so that a lower level of PPE is allowed. If you want to wear more than is recommended, that’s fine.
  • If you’re doing hot work—really working on ac voltage wiring and terminals—suit up. Shirt, pants, helmet, face shield, earplugs, gloves—everything, by the book.
  • For just checking 240-480 voltage below a Class CC or J fused disconnect—gloves, safety glasses, and rated test probes.
  • For 120 V ac and below—just rated test probes.
  • When the doors of the panel are opened and the panel is energized, a physical barrier is to be used and only qualified people should be allowed within that area. If there is not enough room for a barrier, then everyone who passes through that area must receive training on the hazards of electrical equipment.
  • For programming VFDs and just looking inside an ac control panel, a qualified person would not require any protection. Note that an electrical distribution panel is not a control panel.
  • If a VFD setting needs to be changed, or a blown fuse needs replacing (assuming you used finger-safe indicating fuse holders, not open-style holders), or a motor overload needs resetting (when the motor is also protected with properly sized fuses)
  • If you have any components that are not finger-safe with extra covers or don’t have IP20 rating, then the control panel should be labeled as such and extra PPE would be required.

Industrial control panels designed with finger-safe components, fused main disconnects, and ac power segregated from low-voltage dc power can decrease risk.This is a very touchy subject to discuss in public. No one wants to put people in danger. No one wants to have OSHA breathing down their necks. Is the NPFA 70E standard too complex to follow and too restrictive for everyday use? Do we all need to hire electrical PEs to determine the required PPE level? How much money should a system integrator invest in safety equipment? Does every instrumentation tech need his own set of safety equipment? Should industrial control panels have their own arc flash standard? Should we put more of our time and capital into reducing the more hazardous portions of our workplace?

- Tom is a senior controls engineer at a system integrator; he requested that his full name and employer not be used. Edited by Mark T. Hoske, CFE Media, Control Engineering, www.controleng.com.

See related articles for other views and survey link below to share your views. Also, attend an arc-flash webcast at www.plantengineering.com/webcasts.

Take the anonymous Control Engineering – Plant Engineering survey below about industrial control panel safety to give your views about these NFPA 70E PPE risks.

TAKE OUR CONFIDENTIAL SURVEY FOR A LIMITED TIME

Take our anonymous control panel PPE survey [survey is closed - see the results] - This linked 12-question survey is anonymous. Please answer honestly and add comments in the write-in area. Results will be shared with those making the regulations and highlighted in a future issue.

In separate news: New solutions, regulations, address arc flash energy reduction in breakers

Separately, Chris G. Walker, Eaton Corp., explained in a September Plant Engineering article that, “Ideally, work on an electrical system can only be 100% safe if that system is totally de-energized while work is being performed. In many instances, such as in the process industries where facilities are required to operate continuously, a totally de-energized system may not always be possible for these situations. The electrical system may need to be energized to conduct maintenance or to perform trouble-shooting tasks. The steps involved in confirming that an electrical circuit is indeed de-energized, may also put the worker at risk.

“Employees that work in the electrical inspection industry find that they may be exposed to shock and arc flash hazards while conducting the necessary inspections of electrical systems. To help address this, the 2011 Edition of the NEC [1] has a new set of solutions for addressing arc flash energy reduction in circuit breaker applications, in Article 240.87.”

Learn more from Walker on PPE and NEC 2011 safety solutions mentioned above along with figures on relative clearing times for circuit breaker trip functions and time-current curves showing faster trip time with energy-reducing maintenance switching, and a table on the effect of an energy-reducing maintenance switching on incident arc energy.

SURVEY RESULTS: How safe are your electrical system work practices? Survey results show many don’t always follow the rules when working on industrial control equipment. Is failure to wear required protective equipment a foolish choice or an acceptable risk? Clamor for regulatory reform among survey respondents tells the story.

See also the safety and security channel at:

http://www.controleng.com/channels/plant-safety-and-security.html

See the Machine Safety Blog at 

http://www.controleng.com/blogs/machine-safety.html