"I usually get an invitation to teach this safety seminar after a facility has suffered its first fatality." How sad that the instructor of an electrical safety seminar sees this pattern. The key word here is after. The implication is obvious. If the worker had taken the safety awareness training before the time of the accident, it probably would not have happened.
After any serious accident, most people ask a lot of soul-searching questions. What rules did we violate? Did the victim have the adequate tools and training for the job? Did management have a plan in place to minimize the risks?
Adequate safety awareness plans for all electrical construction or maintenance workers should have similarities. Although potential hazards differ in each work environment, most plans involve the same concepts. For example, dividing safety responsibilities between employees helps minimize accidents. Let's look at one typical way to divide these responsibilities.
Dividing safety responsibilities. If you're the group's senior manager, your role in creating a safety awareness program has three parts. * First, choose a senior tradesperson to act as "safety coordinator." This person should develop a comprehensive safety plan. * Second, keep a checklist showing when the group put each item of the safety plan into place. * Third, review the list regularly and hold the appropriate people accountable. It's also a good idea to reward employees who consistently maintain an "accident-free" record.
Creating and implementing a plan. If you're the safety coordinator, it's your responsibility to design and carry out the safety plan. Your job also has three major parts. * First, review existing safety standards that apply to your workplace. These include OSHA, NFPA, IEC, IEEE, ANSI, and ASTM specifications. Get on the mailing list for organizations that generate these standards. * Second, examine the tools and testers each member of your work group uses and ask two questions: Are the tools you have in good condition, and are you missing anything? * Third, schedule a training class for members of your work group. Focus on safe work practices for the tools and testers your group is using. You might decide to teach the class yourself or hire a professional instructor.
If you choose to do all or part of the safety training yourself, contact companies who supply your test equipment and ask for instructional materials. Such materials might include videos and application notes that deal with safe work practices. You should also schedule a regular make-up class for new hires.
Implementing the safety awareness program is significant work for the safety coordinator. Let's look in more detail at the specifics of his or her three-part job.
Safety awareness training. Providing good training can be a challenge because it deals directly with the human elements of the situation. Our own haphazard human judgment can create situations where Murphy's law will supersede Ohm's law. After researching previous accidents, we quickly determine the real danger involved in testing live circuits is not the physics of electricity. Instead, it's human operator complacency. To minimize the risk of complacency, training needs to define safe operating procedures and establish the procedures as habits that people always practice.
Let's define some safe procedures for a typical task and then investigate how we can transform these procedures into habits.
Suppose you have the task of measuring voltage in a service panel (which supplies a branch circuit). The procedure begins the moment you start gathering tools for the job. * Look in your tool belt or tool bucket and make sure you have protective eyewear, 500V gloves, an insulated screwdriver, voltage sensor, current clamp, and multimeter with test leads. * Before you begin, turn on the multimeter to check its battery. Examine its test leads for damage. If the multimeter has a fused current range, check the fuses, as shown in Photo 2 (on page 41). * Size up the surrounding area as you approach the panel. Is there an insulated mat? Is there an easy escape route in case of fire? Can you prop open the door to make a quick exit easier? Can your partner remain nearby while you're working in the open panel? Is there a phone nearby to call for aid in case of an emergency?
So, now you're ready to remove the panel cover. Not so fast! Put on your safety glasses before you reach for the screwdriver. When the cover is off, put on your 500V gloves before you reach for the multimeter. Examine the guts of the panel before you attempt any testing. Look for any damaged insulation or loose wires that could cause a short while you're connecting the test leads. As you set up the function switch on your multimeter, make sure the voltage rating is adequate for the job (i.e., don't use a 600 V multimeter to test a 2.3 kV circuit). Do you have any doubts about the setup? If so, then verify the absence of voltages by testing a known voltage source such as the nearest live wall outlet. This is a good practice for any test equipment, but especially for the pen-sized voltage sensors. These sensors have no indication except when detecting a live voltage. Test the outlet, test your circuits, then test the outlet again.
This next step is important. Look over the service panel carefully and decide on the best place to make a connection. The safest place is usually the load side of the lowest rated protective device (i.e., the output side of the lowest rated circuit breaker or fuse). If you're using alligator clips, never try to grab a screw head. Look instead for a short piece of bare wire or threaded stud. Such items allow you to make a firm, secure connection that won't pop off every time you turn around. Note also the open jaws of an alligator clip can short out adjacent live parts. If you're measuring voltage with respect to ground, make the ground connection first and remove it last. If you need to make a resistance measurement, check the test points for voltage first. Most digital multimeters won't read ohms correctly when voltage is present. If you decide to shut things down to make repairs, make sure to follow all lockout/tagout rules. Always keep your partner informed about what you're doing.
Sure, most electrical professionals recognize the logic behind these procedures. So, what's the problem? The difficulty lies in transforming these procedures into habits. What are habits anyway? How did we get the ones we already have? Webster's dictionary defines a habit as "an act that is automatic" and "a tendency to perform a certain action or behave in a certain way." You need to make safety procedures part of your normal way of doing things. We sometimes program these in because of an experience. If you have ever suffered a severe electric shock, you remember precisely what you were doing and have made sure not to repeat the same mistakes. Since electrical shock is too dangerous to use as a personal learning experience, it makes sense to understand and learn from others' mistakes.
Good safety awareness training presents the details of real life accidents so everyone will have a chance to understand what went wrong. >From a professional standpoint, we all need to share the details of accidents familiar to us and understand how we can prevent them. This author lobbies various magazine editors and electrical organization leaders to publicize the details of accidents in the interest of promoting safety awareness. We can all benefit from incorporating these details into our safety awareness training.
OSHA 1910, Subpart S OSHA 1926, Subparts V and K NFPA 70E, Standard for Electrical Safety Requirements for Employee Workplaces (available from NFPA (800) 344-3555) ANSI/ISA - S82.01 (IEC-1010-1) Safety Standard for Electrical and Electronic Test, Measuring, Controlling, and Related Equipment (Related application note and video available from Fluke Corp. (800) 443-5853) ANSI Z89.1, Requirements for Protective Headwear for Industrial Workers ANSI Z87.1, Practice for Occupational and Educational Eye and Face Protection ASTM D120, Specification for Rubber Insulating Gloves ASTM D178, Specifications for Rubber Insulating Matting ASTM F1506, Standard Specification for Protective Wearing Apparel IEEE 978, Guide for In-Service Maintenance and Testing of Line-Line Tools The list above is a minimum. Additional standards may apply to a particular work activity.
* Verify everyone has a pair of safety glasses. Have spares on hand for immediate replacement of lost or broken pairs. * Verify everyone carries a capacitive voltage sensor. Some people know these as "tick-tracers." These small pen-shaped devices light up or buzz when the tip is near a live conductor. They are inexpensive (usually less than $20) and are the fastest way to detect a live circuit. Choose one that uses replaceable AAA batteries and keep spare batteries on hand. * Verify everyone who works on high-energy circuits has a set of flameproof clothing. * Make sure you install insulated mats in front of switchgear and other appropriate areas. * Buy a pair of 500V rubber gloves with leather protectors. These gloves are surprisingly comfortable. Utility meter people use them regularly on 480V circuits. If you can't find them at your local electrical wholesaler, call the meter foreman at your utility and ask where they buy theirs. * Verify all the appropriate locks and tags are readily available (OSHA lockout/tagout requirements). * Ensure all multimeters and current clamps meet the applicable requirements of ANSI/ISA S82.01. This standard has many details. You can boil them down to the following sentence. If anyone will ever use the tester to work on 480V service panels, then the unit should carry the rating for a minimum of overvoltage installation Category III, 600V. This designation means a lab tested the unit to withstand a 6000V spike from a 2-ohm source without damage. Look for the symbol of an independent testing lab such as UL or CSA. This applies to both the tester and its leads or probes. Have spare test leads available so no one will use a damaged set. If the unit has a fused current input, have spare fuses on hand.
VDT-Specific Lighting Puts Trading Floor In The Spotlight
When the 117-year old securities brokerage house of Fahnestock & Co. relocated from five floors at 110 Wall Street to two larger floors at Two New York Plaza late last year, the firm seized the opportunity to gain excellent lighting on the trading floor. Good lighting on a trading floor is a key factor in promoting productivity and minimizing eyestrain.
With phones in hand, busy traders constantly refer to several closely grouped VDT (video display tube) screens. They must focus on these self-luminous screens, checking fast-moving stock prices from around the world, as they buy and sell. Making sure traders can see the information on their screens, without distracting reflections or glare, is a critical lighting requirement.
When creating the new trading room, Manhattan architect Richard S. Goldberg and partner Robert R. Miller, of RMC Design Associates, used some unique design features to add a sense of openness and spaciousness. The architect also had to develop a comfortable lighting system for people who spend most of their time sitting before a computer screen. Thus, a decade-old standard developed by the Illuminating Engineering Society (IES) served as the main reference source.
The design team created a series of nine bays by constructing soffits made of drywall panels extending 24 in. down from the ceiling plane. Three of the bays are 52 ft long by 14 ft wide; four are 30 ft long by 14 ft wide; and two are 12 ft by 12 ft square. Existing structural beams and HVAC requirements dictated these bays.
The new ceiling height is 10 ft, and the suspended ceiling is fitted with high reflectance 2-ft 2 2-ft ceiling tiles. This tile surface has an exceptional 89% light reflectance and superior sound absorption characteristics. Until now, an 85% reflectance value for a ceiling surface was the numerical value used in design calculations. (Designers installed all power and data communication wiring below the 6-in.-high raised floor system.)
To provide an indirect lighting scheme in these bays, 42 individual "ceiling-wash" (CW) fixtures are recessed in the vertical face of the soffits. Each CW fixture housing is 3 7/8 in. deep, 9 3/4 in. high, and 24 in. long. Each fixture has a single F40 TT5 (twin tube) fluorescent lamp, with a 3500K apparent color temperature, mounted at the bottom of the housing. A cross-section view of this fixture, noted in the diagram, right, shows the curved reflector directs even illumination across the ceiling plane without generating hot spots.
With the CW fixtures mounted about 6 ft on center around the soffits, maximum initial luminance on the ceiling is 720 candelas, within the requirements of RP-1.
According to Goldberg, this system of indirect ceiling-wash lighting fixtures exceeds what a cove lighting system would do in terms of light distribution, at a cost reduction of about $58,000. See the equipment cost of a continuous cove system, compared with the CW fixtures, in the table, on page 88. A cove lighting system could not provide the same uniform horizontal illumination of 30 footcandles (fc) maintained, as achieved in this project.
The bays have a second lighting system to increase uniform illumination across the ceiling plane. Centered within each bay is a row of pendant-mounted fluorescent fixtures suspended at the ends by dual 1/16-in. diameter steel cables. With a 20% direct and 80% indirect light output, each fixture holds two 4-ft T8 fluorescent lamps having a 3500K apparent color temperature. A fully perforated metal housing, backed with an acrylic overlay, shields the lamps from view and produces an overall luminous glow, thus providing an attractive appearance in the center of each bay.
The consulting engineering firm of Joseph R. Loring & Associates, with Victor Jelcic as project engineer, prepared the electrical and mechanical design. The installing electrical contractor was Consolidated Electric Construction Co., Inc. All firms are located in New York City.
The IES/ANSI RP-1 standard recommends a two-component design approach, with ambient indirect lighting combined with portable, adjustable task lighting. It also recommends keeping general lighting levels relatively low when you use supplemental task lighting. To reduce contrast between the VDT screen and the surrounding area and tasks, average maintained illuminance levels should not exceed 50 fc (or 500 lux) on the horizontal work plane. If paper tasks require more fc, use a small adjustable task lighting unit.
To gain a balance of luminance and help eye adaptation, the standard also recommends the ratio of brightness of the near surface (such as the desktop and computer keyboard) to that of the VDT not exceed 3:1. For relationships between remote surfaces and the VDT, the brightness ratio should not exceed 10:1.
On this project, the lighting solution delivers sufficient fc to the entire horizontal work surface without the need for adjustable task lighting on the trading floor desks. Generally, field-conducted mock-up tests show computer users prefer from 30 fc to 35 fc of illumination on the work surface.