Last week, we introduced you to David Hatton, an experienced safety professional who has been involved with life safety codes for more than 36 years, and invited you to send in your questions. Here are your questions and Dave's answers.

THE COST OF NFPA 70E COMPLIANCE

QUESTION

We are a small contract stamper with approximately 30 employees. How do we become compliant with NFPA 70E without spending thousands of dollars? This is in regards to identifying & tagging electrical control boxes for potential arc flash. We had a consultant give us a bid of $15,000.00 to determine the energy level of each control box and the corresponding protection level, (along with layout blue prints).

Thanks.

Gene Everson

ANSWER

Hi Gene,

Your question is one I often hear. The costs associated with compliance under NFPA 70E can appear staggering at first, until you compare the cost of an injury or fatality, due to non-compliance.

Article 130.7 covers "Personal and Other Protective Equipment" selection and use, and NFPA 70 the National Electrical Code, Article 110.16 covers the marking requirements. Let me take the NEC first. The labels are required to warn qualified persons of the potential electrical arc hazards. NFPA 70E outlines the steps necessary to calculate these hazards. The only requirement under the NEC is this warning must be visible to qualified persons, before examination, servicing, adjustment or maintenance of the equipment.

There are two ways to apply the 70E requirements for identifying the hazards. The first is to use table 130.7 (C) (9) (a) Hazard/Risk Category Classifications, covering standard types of work practices used around electrical equipment. The levels of flash protection shown are calculated on average industrial electrical distribution systems, with fault currents and short-circuit clearing times shown in the footnotes to the tables. You can perform your own hazard analysis if you choose, just be aware of the fact that clearing times are a function of both design specifications and proper electrical maintenance. Lack of maintenance, longer clearing times, larger fault currents, or tasks not listed in this table, will kick in the requirements for a flash hazard analysis as described in 130.3.

I suggest that you start with marking the bigger hazards first, and then move on to the other areas in your electrical system, review the types of work that takes place more often, and zero in on those hazards.

The best way to eliminate electrical hazards is to de-energize the equipment, and to start with a policy shift that requires de-energized work at all times. There will be times during troubleshooting that the power will have to be on; this should not be used as an excuse to work it hot if there is another way to solve the problem. OSHA requires the work to be performed de-energized, unless there is a specific hazard analysis conducted that would document the process of review and approval. This approval is called an energized work permit and must be filled out, under specific requirements found in NFPA 70E.

Always remember, "Electrical Safety is Not Expensive, its Priceless". Turn it off, lock it out, and always test for the presence of electrical energy, before any work takes place on the equipment.

ELECTRICAL DO'S AND DON'TS

TWO QUESTIONS

1. I've seen normal outlets installed both ways - ground pin up and ground pin down. Which way is correct and why?
2. A question came up in a recent training session about using breakers for on/off switches.  Several folks said they do that in their buildings and schools (especially for sodium vapor lights, if that makes a difference). I've heard that breakers shouldn't be used that way. Why?

Barry R. Weissman REM, CSP, CHMM, CHS-IV, CIPS

ANSWERS

Thanks for the questions, Barry

1. There are no requirements under the National Electrical Code as to the position of the receptacle, ground up or down. Article 406.4 E only requires installation that is not a "face-up" position on countertops or similar work surfaces. Some people suggest that when metal cover plates are installed that the ground pin faces up, to prevent arcing if the plate falls across exposed plug blades. UL standards require the grounding connection be the first to make and the last to break, leading some to believe the ground pin should face down, and thereby disconnecting last when the cord is pulled down by gravity.
2. NEC section 240.83 states: Circuit breakers used as switches in 120 volt and 277 volt fluorescent lighting circuits shall be listed and marked SWD or HID. Circuit breakers used as switches in high-intensity discharge lighting (sodium vapor are that type) shall be listed and marked as HID (high-intensity discharge). I find that often in existing installations, breakers are not listed for use as switches. You need a qualified person to check these devices out; some are not marked visibly on the face of the breaker. As to why, the breaker can be damaged internally if not rated for switch or HID duty, and this safety hazard, is why the NEC has addressed the issue.

POWER LINE SAFETY

QUESTION

I need help with a recommendation involving electrical power line safety. Let me give you a hypothetical situation. I am operating a forklift or other rubber tire machine. I accidentally come in contact with power lines, but I am not electrified inside the cab. What is the safest thing to do at this point? 1. Should I stay in the cab and try to back out of the power lines? 2. Should I jump from the cab? 3. If I should jump from the cab should I hop away or shuffle my feet? I am trying to confirm some information or tips that I received from someone else.

Thanks
Neil

ANSWER

Thanks Neil for your questions.

The first requirement is to avoid contact with the energized lines in the first place. Unless specifically qualified in electrical safety the minimum distance OSHA requires from electrical parts or lines that must be kept is 10 feet for voltages up to 50,000 volts.

The second point is not to become part of the electrical current flow, and if accidental contact is made with conductive machine parts the best plan is to try to disconnect the contact, but no one recommendation is correct for all possibilities.

The best recommendation is to stay put in the cab or seat and don't touch anything; just sit tight till the power can be turned off. Jumping off the machine is not advisable, due to the currents that are flowing into the earth, even with rubber tired equipment. Tires contain carbon and some have metal fibers, both of them are conductive to electrical current.

Shuffling your feet refers to trying to avoid what we call "step potential", differences of voltages in the earth due to current flow. There are so many possible variables, like voltage, earth resistance and even what type of shoes you're wearing that I would not advise this approach, even though it may look like a safer option than sitting there and doing nothing.

The best solution is to avoid this dangerous situation in the first place, by proper planning and always maintaining safe approach distances around electrical lines and equipment.

Story Tools:  E-mail this to a friend  Print This Post Top