Arc Flash & Electrical Safety

Monday, December 03, 2007

To De-Energize or Not to De-Energize

One of the most important decisions in planning an electric task is whether to de-energize. Whenever possible, live parts to which you might be exposed should be put into an electrically safe work condition, unless your employer can demonstrate that de-energizing creates more or worse hazards, or is not practical because of equipment design or operational limitations.

You might need to work live to avoid interrupting life-support systems, deactivating emergency alarm systems, or shutting down ventilation equipment for hazardous locations, for instance. And de-energizing would not be practical during testing of live electric circuits or work on circuits that are part of a continuous process that cannot be completely shut down.

De-Energizing
An Electrically Safe Work Condition

The most important principle of electric safety is, assume electric circuits are energized unless you make sure they are not. Test every circuit and conductor every time you work on them. The National Fire Protection Association lists six steps to ensure conditions for electrically safe work.

1. Identify all sources of power to the equipment.

2. Interrupt the load current, then open the disconnecting devices for each power source.

3. Where possible, visually verify that blades of disconnecting devices are fully open or that drawout-type circuit breakers are fully withdrawn.

4. Apply lockout/tagout devices in accordance with a formal, written policy.

5. Test each phase conductor or circuit part with an adequately rated voltage detector to verify that the equipment is de-energized. Check the voltage detector before and after each test to be sure it is working.

6. Properly ground all possible sources of induced voltage and stored electric energy (such as, capacitors) before touching. If conductors or circuit parts that are being de-energized could contact other exposed conductors or circuit parts, apply ground-connecting devices rated for the available fault current.

The process of de-energizing is "live" work and can result in an arc flash due to equipment failure. When de-energizing, follow the procedures described below in "Working On or Near Live Circuits."

The above was taken from a NIOSH article that also covers lockout/tagout and information about working on or near live circuits.

Labels: Construction, NIOSH

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Friday, November 30, 2007

Removing the Confusion Over Electrical Standards

"Not sure whether to follow OSHA or National Electrical Code requirements for electrical safety at your construction site? Here is guidance to help you understand the differences in four controversial areas."

That is the subtitle for an article in Occupational Hazards Magazine. The article then defines the problem:

"Electrical safety on construction sites continues to be a major issue. While progress has been made over the years, electrical accidents continue to rank high on the list of construction accidents. In some areas of the country, they are the second leading cause of death or serious injury."

"One reason that electrical accidents occur is because of confusion between National Fire Protection Association (NFPA) and OSHA requirements. Four areas in particular continue to spark controversy or are approached differently by different regulatory standards. There are ways to bring harmony to these four issues by providing recommendations to deal with the differences."

The four areas of confusion discussed in this article are:

Ground-fault circuit-interrupters and Portable Generators

Open Wiring on Insulators

Relocatable Power Taps

Arc Blast and Arc Flash Hazards

For the first three of the above there are updated codes that apply in these areas that are more restrictive than what OSHA requires. For example while OSHA does allow open wiring under some circumstance, NEC 527.4(B) and (C) does not allow it. The article recommends using the stricter code requirements, not because they are stricter but because they are safer.

Arc flash is on the list because arc flash hazards tend to be ignored during construction. The article states:

"In the last few years, considerable progress has been made in industrial facilities after the owners take occupancy. It is during the construction phase that there is little or no attention to this hazard. In many of our code classes for construction electricians, the majority states that this is the first time they have heard about this issue."

The article points out that arc flash is a danger during construction and the requirements of NFPA 70E must be followed during construction.

Labels: Arc Flash, Construction, NFPA 70E

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Wednesday, June 27, 2007

Reaching New Heights

The cover story in the May issue of Electrical Contracting Products is called "Reaching New Heights". It provides a overview of selecting the proper ladder or lift, and of the safety concerns electrical contractors may have with ladders and lifts. It is a good article for anyone who needs to be working above ground level.

The article opens by noting: "According to OSHA, falls are the leading cause of fatalities in the construction industry. From 1995 to 1999, an average 362 fatal falls occurred each year."

After discussing ladder design and ratings, and the selection of the proper ladder material (fiberglass is recommended for electrical work), the three important ladder related questions are identified:

"At what height will you be working from? Many manufacturers will provide a height safety chart that will show the ladders height as well as the maximum safe reaching height."

"What type of jobs will be performed? For instance, not only will you need to consider your own weight, but also the tools you may use while on the ladder. "

"What type of material is appropriate for the job? If the ladder will be used near an electrical hazard, then a non-conductive fiberglass ladder must be selected."

The article also discusses work platforms used for electrical work, such as scissor lifts. It discusses selection criteria, common causes of accidents, safety concerns and maintenance concerns.

Labels: Construction, Electrical Safety

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Wednesday, February 14, 2007

OSHA Issues Final Rule on Electrical Installation Standard

OSHA Press Release

WASHINGTON -- The Occupational Safety and Health Administration published a final rule in today's Federal Register for an updated electrical installation standard.

"These are the first changes to the electrical installation requirements in 25 years, so it is important the standard reflects the most current practices and technologies in the industry," said Assistant Secretary for Occupational Safety and Health Edwin G. Foulke Jr. "The revised standard strengthens employee protections and adds consistency between OSHA's requirements and many state and local building codes which have adopted updated National Fire Protection Association (NFPA) and National Electrical Code provisions."

Changes to OSHA's general industry electrical installation standard focus on safety in the design and installation of electric equipment in the workplace. The updated standard includes a new alternative method for classifying and installing equipment in Class I hazardous locations; new requirements for ground-fault circuit interrupters (GFCIs) and new provisions on wiring for carnivals and similar installations.

The final rule updates the general industry electrical installation requirements to the 2000 edition of the NFPA 70E, which was used as the foundation of the revised standard. The final rule also replaces the reference to the 1971 National Electrical Code in the mandatory appendix to the powered platform standard with a reference to OSHA's electrical installation standard.

Labels: Construction

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Wednesday, November 15, 2006

New Arc Flash Electrical Safety Publications For MCAA Members

The Mechanical Contractors Association of America has developed and produced two resources to assist mechanical service contractors in keeping their workers safe. A recent press release from MCAA states:

MCAA/MSCA Release New Publications on Electrical Safety for Service

ROCKVILLE, MD— The results of an electrical arc flash or uncontrolled electrical current can be devastating. That’s why the National Fire Protection Association (NFPA) has a code for electrical safety in the workplace, and why the Mechanical Contractors Association of America’s (MCAA) Safety and Health Committee developed and produced two resources to assist mechanical service contractors in keeping their workers safe.

Designed especially for mechanical service contractors and based on information from NFPA 70E – 2004, Article 130 – Working On or Near Live Parts, the Model NFPA 70E Electrical Safety Program for Service will help contractors develop an electrical safety program that is specific to their company’s needs if their technicians perform work on or near live parts of HVAC units that are pushing 480 volts or less. Developed in partnership with MCAA’s Mechanical Service Contractors of America (MSCA) subsidiary, the program is available to MCAA and MSCA members for $18 per copy and to nonmembers for $36 per copy.

While this program does not offer extensive information about electrical safety, contractors can find additional information in another MCAA publication: the Electrical Safety Guidelines for Mechanical Service (Based on NFPA 70E – 2004) Safety Training Kit. Designed especially for mechanical service workers who troubleshoot energized HVAC units pushing 480 volts or less, the kit will help contractors educate their workers about arc flash and electrical shock hazards.

It describes:

• Electrical arc flash and shock hazards associated with work on energized units pushing 480 volts or less,

• Safe work practices/protective measures, including arc flash and electrical shock
approach boundaries, and

• Personal protective equipment.

The kit includes a 14-minute safety training DVD, a set of 20 pocket guides that enhance the training by highlighting its key points, and a training documentation system.

Much of the critical information in the kit comes from a section of an addendum to the NFPA National Electrical Codes. The addendum, which is referred to as NFPA 70E, spells out the best present-day safety practices for workers exposed to energized electrical sources.

The kit is available to MCAA and MSCA members for $85 and to nonmembers for $170. The
items in the kit are also available separately in case contractors need more of just one or two.

Additional copies of the documentation system are $6 for MCAA and MSCA members and $12 for nonmembers; additional sets of pocket guides are $14 for MCAA and MSCA members and $28 for nonmembers; and additional DVDs are $65 for MCAA and MSCA members and $130 for nonmembers.

To order either of these publications, visit MCAA’s online store at ww.mcaa.org/store or call Linda Burke at 301-990-2200.

The Mechanical Contractors Association of America (MCAA) serves the unique needs of
approximately 2,300 firms involved in heating, air conditioning, refrigeration, plumbing, piping, and mechanical service. We do this by providing our members with high-quality educational materials and programs to help them attain the highest level of managerial and technical expertise. MCAA includes the Mechanical Service Contractors of America, the National Certified Pipe Welding Bureau, the Plumbing Contractors of America, and the Manufacturer/Supplier Council.

Labels: Arc Flash, Arc Flash Training, Construction

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Thursday, October 19, 2006

ELCOSH: Protection from Electric Shock and Arc Flash

The Electronic Library of Construction Occupational Safety and Health (CDC) has a detailed article about arc flash protection and PPE. The section on PPE in particular is excellent, providing more detail that I've seen elsewhere.

The topics covered in this article include:

Electric hazards

Electric Safety Principles

To De-Energize or Not to De-Energize

Working On or Near Live Circuits

The article is available at: http://www.cdc.gov/elcosh/docs/d0500/d000580/d000580.html

Labels: Arc Flash, Construction

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Monday, July 24, 2006

OSHA Answers A Letter About NFPA 70E

A letter written by OSHA to Associated General Contractors of Indiana, Inc., in response to questions sent to OSHA, provides some helpful information for understanding the application of NFPA 70E.

The letter discusses the answers to five questions:

1. Is a general contractor required to oversee a subcontractor's compliance with NFPA 70E? In their responses OSHA discusses the General Duty Clause and the OSHA Multi-employer Citation Policy.

2. OSHA has not incorporated the personal protective equipment portions of NFPA 70E? Does an employer have an obligation under the General Duty Clause to ensure that its own employees comply with personal protective equipment requirements in NFPA 70E?

3. an an employer be cited for violating an OSHA requirement for personal fall protection (PPE) where a properly trained employee decides not to wear the PPE?

4. Are there OSHA standards that state that an owner of a work facility must identify and mark electrical hazards for contractors?

5. How can I distinguish between electrical work that is considered "construction work" and electrical work that is considered "general industry work"?

Labels: Construction, Electrical Hazards

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