Journeyman Electrician: The Basics of Precautions

Approaching a Job
Electricians must know the code rules and regulations so they can perform jobs correctly and safely, and must also use sound judgment when working.  The most important safety tip, especially in hazardous locations, is to be alert.
The electrician’s tools and equipment must be appropriate for the job and be in good repair. Defective or altered tools can cause accidents.
A proper fire extinguisher should always be accessible. 
Chemical extinguishers should be used in case of an electrical fire as water on an electrical fire may shock the user.  The best electrical fire extinguisher type uses CO2.
Circuits must be considered hot unless known to be otherwise, and power should be removed when this is practical.  When working on a motor, always remove its fuses or otherwise de-energize the circuit to avoid accidental starting.  Two people should be present when working on high voltage so that one can provide help if an accident occurs.

Performing a Job
When moving heavy objects, use your legs and arms when lifting and keep your back as upright as possible while spreading your feet to provide a solid base.
Using ladders: a common cause of falls from ladders is becoming unbalanced while carrying or exerting a pull on a heavy object.  A ladder that is painted might be unsafe because the paint could conceal damage to the rungs or rails.
Insulated tools: the safety value of insulation on tools should not be the electrician’s only protective measure.  Always use leather gloves over rubber when working on live 600 volt equipment.  Rubber gloves for use with high voltage should always be tested with high voltage.  Sponge rubber soled shoes can be punctured by nails.

Tools and Equipment Safety
All branch circuits are protected by fuses or circuit breakers, and in some cases GFCIs.  These are installed primarily to protect the electrical system and users, but they also offer some protection to the electrician.
Some equipment may contain an interlock which is a device that, when actuated, causes other devices associated with it to be disabled. 
An example of an electrical interlock is a switch on a heating system that prevents operation of the heater or fan when the cover is removed.  Some panels are mechanically prevented from being opened unless the power switch is moved to the off position.  For maximum safety, magnetic contactors should always be electrically and mechanically interlocked.
Power tools are either double insulated or have a grounded frame to prevent them from receiving a stray voltage and becoming live.
If a live wire is touched accidentally, the severity of a shock is directly determined by the contact resistance between operator and the power source.  Insulating tools and clothing are therefore helpful in reducing the risk of injury from shocks.

Grounding Electrical Equipment
Electrical devices have their external metal surfaces grounded to limit excess voltage to ground caused by lightning or unintended exposure to circuit voltages.  In the case of inadvertent exposure to a stray voltage, this also provides a short circuit to ground that will trip the branch circuit breaker and remove the hazard.
The grounded conductor of a lighting circuit is always connected to a screw on the device to reduce the possibility of electrical shock.  A grounding wire is used for the same reason on any metal cabinet.
The earth ground is developed at the utility pole or the service panel and requires a metal rod to be inserted into the earth.  To ensure a low resistance path to this earth ground, sometimes multiple rods or treatment of the soil are required.  The connection at the service of the ground to the grounding conductors is called the main bonding jumper.

Injuries
The most important first step for the safety of a worker who has been injured and for the personnel attempting to help is to remove the hazard.  Never approach a victim of an electrical injury until the power is off or isolated.  If a victim is still in contact with a live wire, use a dry rope or stick to remove the wire.
Sometimes it is not obvious that a significant injury has occurred.  Normal signals of electrical injury include erratic pulse, being dazed or confused, or unconsciousness.
Burns can be disabling, disfiguring, or even life threatening.  When a person is burned, cover and cool the injured area while taking steps to prevent shock and infection.  First aid for acid burns is to flush with water, then apply petroleum jelly to keep air from the wound.  When a chemical is splashed into the eyes, always flush them with clean water.
If someone has been injured and is going into shock, the most important step is to keep them warm.  If a victim is not breathing, it is also critical to start artificial respiration immediately.
An accident report probably will be required after an injury occurs.  It is important to determine and report the cause of the accident in order to prevent it from happening again.
Nonincendive equipment is that which is not capable of igniting flammable vapors from arcs or heat within the device.
Dusttight means built so dust will not enter the outer case under normal conditions.
Dust-ignition proof equipment is enclosed in a way that prevents dust from entering and also does not permit arcs or heat inside of the enclosure to ignite vapors near the device.
Explosion proof devices are those that are enclosed in a case that is capable of withstanding an explosion occurring inside it without igniting a specified gas or vapor outside the enclosure.