Whenever work is done on equipment that is normally connected to
an energy source such as electricity, pressure, and steam, personnel
may be exposed to source-related hazards. This Standard documents
BNL safety requirements for the control of hazardous energy, and
addresses the practices and procedures necessary to disable
machinery or equipment to prevent unexpected energization, start-up
or release of stored energy, which may result in injury to employees
during maintenance, servicing, or construction.
Safety interlocks are appropriate for personnel protection in many
situations where there is danger from sources of energy. The use of
interlocks for personnel protection rather than sole reliance on
administrative controls, depends on the nature and severity of the
hazard and on the interactions of personnel with the hazard.
Interlock systems act automatically to protect personnel from
danger, and are valuable where exposure to a hazard is frequent or
routine and human error is likely. Primary safety shall be provided
by proper operating procedures. When appropriate a Safety Analysis
Document (SAD) or Safety Analysis Report (SAR) shall be in place
which embodies commitments to operate the facility according to
stated procedures and within a stated safety envelope. If an
interlock system is required, the design and implementation must be
adequate to assure that the facility operates in compliance with the
SAD/SAR. Individuals tend to rely on interlock protection, and a
poorly designed interlock or one which is not maintained or tested
may actually increase the likelihood of an accident. For this reason
the use of a safety interlock system carries technical design
requirements, as well as an ongoing responsibility for maintaining,
testing and controlling its configuration.
Last Modified: February 1, 2008
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