INTRODUCTION

Electricity has become an essential of modern life, both at home and on the job. Some employees work with electricity directly, as is the case with engineers, electricians, or people who do wiring, such as overhead lines, cable harnesses, or circuit assemblies. Others, such as office workers and salespeople, work with it indirectly. As a source of power, electricity is accepted without much thought to the hazards encountered. Perhaps because it has become such a familiar part of our surroundings, it often is not treated with the respect it deserves.
OSHA's electrical standards address the government's concern that electricity has long been recognized as a serious workplace hazard, exposing employees to such dangers as electric shock, electrocution, fires and explosions. The objective of the standards is to minimize such potential hazards by specifying design characteristics of safety in use of electrical equipment and systems.
OSHA's electrical standards were carefully developed to cover only those parts of any electrical system that an employee would normally use or contact. The exposed and/or operating elements of an electrical installation - lighting equipment, motors, machines, appliances, switches, controls, enclosures, etc. - must be so constructed and installed as to minimize electrical dangers to people in any workplace.
The OSHA electrical standards were based on the National Fire Protection Association's standard NFPA 70E, Electrical Safety Requirements for Employee Workplaces, and the NFPA 70 Committee derived Part I of their document from the 1978 edition of the National Electrical Code (NEC). The standards extracted from the NEC were those considered to most directly apply to employee safety and least likely to change with each new edition of the NEC. OSHA's electrical standards are performance oriented; therefore they contain few direct references to the NEC. However, the NEC contains specific information as to how the required performance can be obtained.
This discussion does not cover OSHA's Electrical Safety-Related Work Practices Standard, which contains requirements for working on or near energized and de-energized electrical equipment, the use of personal protective equipment, and the safe use of electrical equipment.
This discussion covers requirements in OSHA's Design Safety Standards for Electrical Systems that are frequently overlooked and may present serious hazards. The reader is encouraged to consult the complete text of OSHA's electrical standards for all of OSHA's requirements.

EXAMINATION, INSTALLATION AND USE OF EQUIPMENT

Examination

Electrical equipment shall be free from recognized hazards that are likely to cause death or serious physical harm to employees.(1) Safety of equipment shall be determined using the following considerations:

	Suitability for installation and use in conformity with the provisions of this subpart. Suitability of equipment for an identified purpose may be evidenced by listing or labeling for that identified purpose.
	Mechanical strength and durability, including, for parts designed to enclose and protect other equipment, the adequacy of the protection thus provided.
	Electrical insulation.
	Heating effects under conditions of use.
	Arcing effects.
	Classification by type, size, voltage, current capacity, and specific use.
	Other factors which contribute to the practical safeguarding of employees using or likely to come in contact with the equipment.

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FOOTNOTE(1) Note that this requirement is, in effect, and electrical "general duty clause" similar to Section 5(a)(1) of the OSH Act: "each employer shall furnish . . . a place of employment which is free from recognized hazards that are causing or are likely to cause death or serious harm to his employees."

Installation and Use

Listed or labeled equipment shall be used or installed in accordance with any instructions included in the listing or labeling.

IDENTIFICATION OF DISCONNECTING MEANS AND CIRCUITS

Each disconnecting means required by this subpart for motors and appliances shall be legibly marked to indicate its purpose, unless located and arranged so the purpose is evident. Each service, feeder, and branch circuit, at its disconnecting means or overcurrent device, shall be legibly marked to indicate its purpose, unless located and arranged so the purpose is evident. These markings shall be of sufficient durability to withstand the environment involved.

A disconnecting means is a switch that is used to disconnect the conductors of a circuit from the source of electric current. Disconnect switches are important because they enable a circuit to be opened, stopping the flow of electricity, and thus can effectively protect workers and equipment.

Each disconnect switch or overcurrent device required for a service, feeder, or branch circuit must be clearly labeled to indicate the circuit's function, and the label or marking should be located at the point where the circuit originates. For example, on a panel that controls several motors or on a motor control center, each disconnect must be clearly marked to indicate the motor to which each circuit is connected. In the figure below, the Number 2 circuit breaker in the panel box supplies current only to disconnect Number 2, which in turn controls the current to motor Number 2. This current to motor Number 2 can be shut off by the Number 2 circuit breaker or the Number 2 disconnect.

If the purpose of the circuit is obvious, no identification of the disconnect is required.

All labels and markings must be durable enough to withstand weather, chemicals, heat, corrosion, or any other environment to which they may be exposed.


  

Each Disconnect and Circuit Requires Identification

WORKING SPACE ABOUT ELECTRIC EQUIPMENT


Note that this particular section is concerned with the safety of a person qualified to work on the equipment (presumably an electrician). Obviously, the hazard must be treated in a different way if the person will remove guards and enclosures and actually work on the live parts. Sufficient access and working space shall be provided and maintained about all electric equipment to permit ready and safe operation and maintenance of such equipment.

Clear Spaces

Working space required by this subpart may not be used for storage. When normally enclosed live parts are exposed for inspection or servicing, the working space, if in a passageway or general open space, shall be suitably guarded.

GUARDING OF LIVE PARTS

It should be noted that the purpose of this requirement is to protect any person who may be in the vicinity of electrical equipment against accidental contact. These people are presumably not electricians working on the equipment, and are not qualified or trained to be in close proximity to live parts.

Except as required or permitted elsewhere in this subpart, live parts of electric equipment operating at 50 volts or more shall be guarded against accidental contact by approved cabinets or other forms of approved enclosures, or by any of the following means:

	By location in a room, vault, or similar enclosure that is accessible only to qualified persons.
	By suitable permanent, substantial partitions or screens so arranged that only qualified persons will have access to the space within reach of the live parts. Any openings in such partitions or screens shall be so sized and located that persons are not likely to come into accidental contact with the live parts or to bring conducting objects into contact with them. It is good practice to use covers, screens or partitions which can only be removed by use of tools, so that unqualified persons are less likely to violate them.
	By location on a suitable balcony, gallery, or platform.
	By elevation of 8 feet or more above the floor or other working surface. Note that, although equipment elevated at least 8 feet is considered to be guarded, this may not be adequate if material being handled is likely to make contact with live parts.

In locations where electric equipment would be exposed to physical damage, enclosures or guards shall be so arranged and of such strength as to prevent such damage.

Entrances to rooms and other guarded locations containing exposed live parts shall be marked with conspicuous warning signs forbidding unqualified persons to enter.

You should be constantly aware of hazards in your workplace. New work or changes may create a new hazard, or poor maintenance may allow reappearance of old ones.