Hazardous energy control is not optional these days. It is
required by law for all employees who work on de-energized equipment where
there is potential for injury if the equipment is unexpectedly re-energized.
This is an extremely important part of the overall electrical safety program,
not only because it is the law, but also because it is a key effective method
toward ensuring that employees have the electrically safe work condition.
It is often called a lockout/tagout program. OSHA regulation
29 CFR 1910.333(b)(2) states: “While any employee is exposed to contact with
parts of fixed electrical equipment or circuits which have been deenergized,
the circuits energizing the parts shall be locked out or tagged out or both in
accordance with the requirements of this paragraph.”
That paragraph covers the following subjects:
a) Establishment and maintenance of written procedures for
lockout/tagout;
b) Establishment of safe procedures for de-energizing
equipment;
c) Requirements for the use of locks and tags;
d) Verification of the de-energized condition;
e) Requirements before re-energizing the circuits.
This means that a hazardous energy control program shall be
established to cover all employees whose jobs could possibly expose them to
energized electrical conductors or circuit parts. Hazardous energy control of
electrically operated equipment is important to nonelectrical workers also.
Consider the following examples:
-Two mechanics working on a crane runway were knocked 40 ft
to the floor below when a control-circuit failure caused the crane to start
unexpectedly.
- A pipe fitter was scalded when an operator depressed the
“open” button on a motor operated valve.
- A two-man cleanup crew was buried in a storage silo when a
conveyor was started accidentally.
- A hopper gate closed on the torso of a welder who was
repairing the hopper lining.
All of these accidents have a common denominator. Although
none involved electricians, nor electric shock or electrocution, all were
electrically initiated. Furthermore, none would have occurred if proper electrical
energy control procedures had been in effect.
A hazardous energy control procedure is a part of providing
an electrically safe work condition for employees. This procedure is applicable
to work on electrical equipment at all voltage levels, not just for higher
voltage systems.
Hazardous energy control procedures, in the electrical
business, are often referred to as lockout/tagout procedures. There are several
existing documents in which lockout/tagout procedures are discussed in detail.
ANSI Z244.1-1982 is a document that provides good guidance for establishing
lockout/tagout procedures. ANSI Z244.1-1982 has a sample lockout/ tagout
procedure in its appendix.
It is quite obvious that the U.S. federal government is
serious about control of hazardous energy in the workplace. OSHA regulation 29
CFR 1910.147 covers hazardous energy control in general and includes all kinds
of hazardous energy, not just electrical. This document also contains a sample
of a minimal lockout/tagout procedure.
OSHA regulation 29 CFR 1910.333 is speciÞcally aimed at
lockout/tagout for electrical work in general industry. OSHA regulation 29 CFR
1926.417 discusses lockout and tagging of circuits for the construction
industry.
OSHA regulation 29 CFR 1910.269 discusses lockout/tagout
requirements for power generation, transmission, and distribution type work.
Lockout/tagout practices and devices, including training, retraining,
equipment, and procedures, are discussed in NFPA 70E-1995, Part II, Chapter 5.
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