TITLE:	ES&H Manual
DOCUMENT ID:	6210 General Electrical Safety

1.0 Introduction

Electrical energy is one of the most unforgiving hazards, capable of causing severe personal injury, death, or fire. On average about 500 people in the U.S. die from electrical accidents every year. Not all of these are electrocutions. Electrical arcs and equipment explosions cause fatal burns, as well as blindness and trauma. In addition, there are about 4000 non-fatal electrical injuries per year that result in lost workdays.

Essentially all equipment at Jefferson Lab is dependent upon electrical energy. To protect people from both direct and indirect hazards produced by electricity, Jefferson Lab has standardized guidance for work involving electrical or electronic equipment. This includes all work performed under the direction of Jefferson Science Associates, LLC (JSA)/Jefferson Lab. The equipment construction requirements apply as well to experimental equipment fabricated off-site by facility users.

This chapter outlines the electrical safety program at Jefferson Lab. It provides a basic discussion of the hazards of electricity and important hazard control practices that are useful for laboratory staff who do not have electrical training and experience. Three related chapters provide specific guidance for electrical construction and maintenance activities, and those chapters are targeted to the trained and experienced personnel who are authorized for these tasks.

ES&H Manual Chapter 6220 AC Electrical Equipment Safe Work Policy

ES&H Manual Chapter 6230 Electronic Equipment Safe Work Policy

ES&H Manual Chapter 6240 Electronic Equipment – Construction and Modification Safety

Other chapters that may be useful for you:

ES&H Manual Chapter 6105 Office Safety

ES&H Manual Chapter 6110 Lock, Tag, Try (LTT) Policy

ES&H Manual Chapter 6120 Hand Powered Tools

2.0 Hazard Avoidance

Energized electrical equipment can be very dangerous, frequently lethal. You or an unsuspecting bystander can be killed or maimed by electrical energy that is not well controlled. If you are not confident of your ability to work safely with a piece of electrical or electronic equipment, don’t do it. Seek the appropriate assistance or training.

2.1 To avoid exposure to electrical hazards:

· Use only properly grounded or double-insulated equipment.

· Don’t open enclosures of energized electrical equipment.

· Don’t attempt to service or repair equipment unless you are trained and authorized to do so.

· Avoid any use of electrical equipment under wet conditions.

· Don’t use damaged power cords or equipment.

· Always hold cords by plug when removing them from receptacles. Never “whip” a cord to unplug it.

· Minimize your use of extension cord and avoid “Daisy Chains” of cords.

· Understand the importance of and respect lockout and tagout of electrical systems.

· Don’t reset a circuit breaker if it trips more than twice, and if a breaker is very warm to the touch, do not attempt to reset it at all.

· Keep all parts of your body away from potentially energized devices.

	Voltage range (phase to phase)	Minimum approach distance
	300V and less	Avoid contact
	Over 300V, not over 750V	1 ft. (30.5 cm)
	Over 750V, not over 2kV	1 ft. 6 in. (46 cm)
	Over 2kV, not over 15kV	2 ft. (61 cm)
	Over 15kV, not over 37kV	3 ft. (91 cm)
	Minimum distance of ladders, cranes, manlifts, etc. to overhead conductors	10 feet

3.0 Biological effects of electric shock

The effects produced by an electrical shock are a function of the duration, quantity, frequency, and path of the current passing through the body, as well as skin moisture.

Your nervous system is an electrical network that uses extremely low currents. An electric shock – with even very low current – can disrupt normal functioning of muscles – most significantly, your heart. Electricity also produces violent muscle contractions which is why a person receiving a shock is frequently unable to “let go.” It also may cause the heart to lose its coordination or rhythm. These effects can be caused by currents that produce no noticeable heating of tissue or visible injury.

Electrical shock can also produce rapid and destructive heating of body tissue. Seemingly minor external effects (burns specifically) may be indicative of much more extensive internal injury. There are other, potentially delayed effects. Always seek medical attention after an electrical shock – no matter how minor it seems.

Table 1: Effect of current on the human body

	Current in milliamperes
Effect	DC	AC (60 Hz)
Slight sensation at contact point	0.6	0.3
Perception threshold	3.5	0.7
Shock – not painful, no loss of muscular control	6	1.2
Shock – painful, no loss of muscular control	41	6
Shock – painful, let-go threshold	51	10.5*
Shock – painful, severe effects: muscular contractions, breathing difficulty	60	15
Shock – possible ventricular fibrillation (loss of normal heart rhythm)	500	100

Data are based on limited experimental tests and not intended to indicate precise values.

* The threshold for a painful shock, in which muscles cannot let go, is 10.5 mA for AC current.

Circuit breakers trip at 15-20 amperes or higher – more than 200 times the lethal current. They are intended to prevent electrical fires, not protect you from shock.

Circuit breakers trip at 15-20 amperes or higher – more than 200 times the lethal current. They are intended to prevent electrical fires, not protect you from shock.

Table 2: Typical Human Body Resistance to Electrical Current

Body Area	Resistance (ohms)
Dry skin	100,000 to 600,000
Wet skin	1,000
Internal body (hand to foot)	400 to 600
Ear to ear	~100

Barring broken skin, body-circuit resistance, even in contact with liquid, will probably be not less than 500 ohms. However, the current flow at this resistance and 120 volts is 240 milliamperes – over twice what is required to cause death.

4.0 Other effects of electricity:

· Electrical Arc Flash

When an electrical arc occurs, it can produce temperatures up to 35,000° F. This melts and vaporizes the constituents of the conductor, rapidly heating the surrounding air – with potentially explosive force. One cubic inch of copper, for example, produces 1.44 cubic yards of vapor. This is comparable to the expansion rate of dynamite. Electrical explosions can be fatal within 10 feet of the arc, and can cause burns up to 40 feet away.

· Damage to electrical equipment from excessive current and arcing.

· Unplanned shutdown of equipment, from office computers to the accelerator.

5.0 Responsibilities

5.1 Individuals and supervisors

· Ensure that only qualified individuals construct or service electrical or electronic equipment and that the work is accomplished as set forth in this manual.

· Ensure, that to the extent practicable, all work on electrical or electronic equipment is performed while the equipment is de-energized.

· Ensure that all manipulative work with hazardous voltage and current follows a written plan with appropriate approvals. (Hazard Classes and Modes are defined in “Program Summary.”)

5.2 Electrical Safety Committee

The Electrical Safety Committee (ESC) has members from all divisions and it promotes electrical safety at the Lab. It provides interpretations to electrical codes and standards, reviews proposed changes to Lab electrical policies and practices, and serves as the technical advisor to the Facilities Management Director who serves as the on-site electrical authority having jurisdiction.

5.3 Facilities Management (F.M.) Director

Provide services as the on-site authority having jurisdiction (AHJ) for the design, installation, and maintenance of building electrical systems. The F.M. director prepares and submits requests for code waivers and variances to the relevant external authority.

6.0 Qualifications

There are several types of electrical work for which Jefferson Lab requires journeyman or master electrician credentials. These include:

· Premises Wiring – Installation of electrical conductors and equipment to, within, exterior to buildings, and temporary electrical service facilities.

· Design and Approval of the above tasks, and Inspection and acceptance of completed work.

It is the cognizant supervisor/sponsor/ Subcontracting Officer’s Technical Representative’s (SOTR’s) responsibility to ensure that staff who are assigned to these tasks have the appropriate training and credentials. Supervisors may use other staff with electrical expertise as a resource in determining qualifications.

6.1 Other Electrical & Electronic Workers

We perform many other electrical-related tasks at Jefferson Lab that do not fall into these categories. Supervisors are required to identify the necessary qualifications for electrical work capable of causing injury, and ensure that only those staff with the appropriate skills and experience are assigned to the work. The rationale and the name of the people performing the work shall both be documented. This can be via ESH&Q training records (for Jefferson Lab-provided and off-site training), work control documents (such as Standard Operating Procedure [SOPs] and Operational Safety Procedure [OSPs]), division/work group proficiency records, or combinations of these. Qualifying people by mode and class of electrical hazard is another alternative.

See ES&H Manual Chapters 6220 AC Electrical Equipment Safe Work Policy and 6230 Electronic Equipment Safe Work Policy for details on electrical power classes, work modes, and work restrictions.

7.0 Safety Measures For Preventing Accidents

7.1 Ensure that the work is properly planned

Identify needed

· worker skills

· parts and tools

· scheduling and access

· documentation

Planning for a potentially hazardous activity includes a search for engineering and administrative measures that reduce both the hazards and the exposure of people to danger. For example,

· installing a temporary protective barrier

· minimizing the number of people involved

7.2 Personal Protective Clothing and Equipment

The selection of appropriate protective clothing and equipment for a particular activity is a function of the hazards and degree of personnel exposure inherent in the activity. Supervisors shall assess each situation, then define and enforce an appropriate level of protection for the personnel engaged in the activity. See ES&H Manual Chapter 6620 Personal Protective Equipment

7.3 Elevated Work

Any person working on electrical equipment from a ladder, scaffold, crane, cable tray, or other elevated location four feet or more above the floor, shall take precautions to prevent a fall from reaction to electrical shock or other causes. This may mean the use of a safety harness, guardrails, or safety net. When required by mode and class, the second person, qualified as a Safety Watch, shall assume the best possible position to assist the worker in case of an accident. See also ES&H Manual Chapters 6131 Trip and Fall Protection and 6132 Ladders and Scaffolds.

7.4 Excavation, Digging, Floor/Wall Penetrations, and Demolition

Jefferson Lab has many buried electrical circuits site wide. Also, most buildings have conduit within walls and imbedded in floor slabs. If you have work that requires digging or drilling into soil or penetration into walls or floors with tools or fasteners, call Facilities Management (x7673) to request utility location services.

Identifying circuits and other utilities before work can save your life and prevent expensive damage. In addition, never assume a circuit, conduit, pipe, or other utility device is “dead” until that fact has been verified by a qualified person (QP).

7.5 Additional safety practices:

· Maintain an up-to-date set of documentation for safe operation, maintenance, and testing for work on hazardous equipment.

· Remove clothing and jewelry that might increase the danger of working on electrical or electronic equipment.

· Use protective equipment appropriate to the task.

· Use lockout/tagout (LO/TO) procedures. See ES&H Manual Chapter 6110 Lock, Tag, Try (LTT) Policy.

· Exclude from hazardous work anyone who appears to be fatigued, ill, emotionally disturbed, or whose performance is otherwise impaired.

· When in doubt, stop and reassess the safety of the situation.

· Conduct training sessions and drills periodically to help prevent accidents and to train people to respond effectively if an accident does occur.

· Preserve ground continuity during operation and testing.

· Use appropriate tools with intact insulation.

· Use ground-fault circuit-interrupter (GFCI) whenever required or recommended. See ES&H Manual Chapter 6210 Appendix T1 Ground-Fault Protection for GFCI locations.

· Recognize that equipment combining high voltage (>10kV) and vacuum has the potential of becoming a source of x-rays. Be sure that such systems have been reviewed. See ES&H Manual Chapter 6310 Ionizing Radiation Protection.

· If required by your job, maintain your proficiency in cardiopulmonary resuscitation (CPR) and the use of automatic external defibrillators (AED). Note that Jefferson Lab has several AEDs installed in wall-mounted enclosures on site, available for use by any trained person.

7.6 Additional electrical safety guidance may be found in

· National Fire Protection Association (NFPA) 70 National Electrical Safety Code.

· NFPA 70E Standard for Electrical Safety Requirements for Employee Workplaces.

· 29 Code of Federal Regulation 1910, General Industry (OSHA).

· 29 Code of Federal Regulation 1926, Construction (OSHA).

These references are available through your ESH&Q staff and Division Safety Officer.

8.0 Program Summary

8.1 Electrical Distribution vs. Electric/Electronic Utilization Equipment

The equipment used to distribute AC electrical line power is treated separately from the electrical and electronic equipment that conditions, controls, and uses this power.

· ES&H Manual Chapter 6220 AC Electrical Equipment Safe Work Policy describes the responsibilities for and restrictions placed on work involving AC line power distribution equipment.

Specific safety requirements apply to servicing and constructing electrical equipment. They are especially important when a worker must service hazardous electrical or electronic equipment while it is energized. The following additional chapters cover these topics.

· ES&H Manual Chapter 6230 Electronic Equipment Safe Work Policy addresses the service restrictions for work on all electronic equipment.

· ES&H Manual Chapter 6240 Electronic Equipment – Construction and Modification Safety details techniques used to ensure that electrical and electronic equipment remains safe and establishes restrictions on work involving electrical utilization equipment.

Electrical Work Restrictions (or work rules) are established according to hazard class and mode of work.

The mode is determined by the nature of the work:

· de-energized

· energized with reduced safety and restricted manipulative operations

· energized with manipulative operations

The hazard class is determined by:

· the type of work – electrical or electronic – and the combination of voltage and current

Table 3 summarizes Jefferson Lab’s electrical hazard class and work mode system as well as the associated work restrictions. For full details, you need to refer to the chapter that discusses the type of electrical system you will be working on.

Important reminder: These work practices and precautions are the minimum required. Managers or supervisors may specify more restrictive or augmented procedures.

Table 3: Electrical Hazard Classes and Work Modes

	Mode of Work
Hazard Class	1 De-energized equipment, LO/TO in place	2 Measurement, troubleshooting of energized equipment	3 Manipulative, hands-on tasks on energized equipment
Low hazard < 50V & < 50A (low voltage, low power)	A QP may work alone.	A QP may work alone.	A QP may work alone. Management approval and general supervision required.
II Medium hazard 50-120 VAC/DC line-to-neutral > 50A 208/220 VAC line-to-line stored charge > 10 joules	2 QPs must be present until equipment is verified as de-energized. One QP may then work alone.	At least 2 QPs must be present. Management approval and general supervision required.	2 QPs must be present. Standard Operating Procedure (SOP) or Electrical Service Work Permit is required. Appropriate eye protection, insulated tools, and gloves.
III High hazard 277 VAC line-to-neutral 480 VAC line-to-line	2 QPs must be present until equipment is verified as de-energized. One QP may then work alone.	At least 2 QPs must be present. Management approval and general supervision required.	2 QPs must be present, one acting as Safety Watch. SOP or Electrical Service Work Permit is required. Appropriate eye protection, insulated tools, and gloves.
IV Extreme hazard > 600 VAC line-to-line	2 QPs must be present until equipment is verified as de-energized. One QP may then work alone.	Eye protection, insulated tools, gloves, floor mat – all rated for the expected hazard. 2 QPs required; one as Safety Watch in continuous communication.	No JSA/Jefferson Lab or subcontractor personnel may work in these conditions. Commercial power utility personnel and their subcontractors only.

Notes:

Voltage is line-to-neutral or line-to-line, whichever is higher.

Class is determined by the highest voltage or current to which personnel may be exposed during servicing operations.

Hazard Class I includes equipment with voltages > 50V, but with current capability < 5mA and stored energy < 1 joule.

Note: The second qualified person may serve as the Safety Watch.

ISSUING AUTHORITY	CHAPTER AUTHOR	APPROVAL DATE	EFFECTIVE DATE	EXPIRATION DATE	REV.
ESH&Q Division	Todd Kujawa	08/17/06	08/17/06	08/17/09	0

This document is controlled as an on line file. It may be printed but the print copy is not a controlled document. It is the user’s responsibility to ensure that the document is the same revision as the current on line file. This copy was printed on 8/25/2009.