Locks and Padlocks. Built-in locks on switchgear and disconnecting switches should
be used whenever the equipment is tagged, and the keys should be returned to the supervisor
responsible for their control. Padlocks need not be used if it is decided that use and control of
such locks would be difficult because of the type of switchgear and its location. However,
padlocks should be used with "DANGER" tags when equipment or electrical lines remain out of
service or electrical work has been discontinued until a later date. When outside contractors are
involved, each contractor should attach and control tags and locks independently.
Safety Board Inspection. The equipment located on the safety board should be
inspected as indicated below:
a) Rubber gloves should be tested in accordance with ASTM D120, Insulated Rubber
Gloves. ASTM specifications may be obtained from the American Society for Testing and
Materials, 1916 Race Street, Philadelphia, PA 19103.
b) Testing may be performed by qualified private testing laboratories, utility
companies, and large military or Federal establishments.
c) Gloves should be proof-tested at the following intervals: in daily use--30 days; or
infrequent use--180 days. Gloves suspected of having defects should be proof-tested; gloves
received from the manufacturer should be inspected and proof-tested.
d) Hot-sticks should be visually inspected for paint smears, carbon paths, dirt smears,
etc., and cleaned, if required, prior to use. Hot-sticks which cannot be cleaned or have
significant surface-coating ruptures should be resurfaced and tested.
Certified rubber gloves and protective leather gauntlets should be worn whenever
hot-sticks are used.
Safety Checklist. A safety inspection should be completed on a monthly basis to
ensure that the safety boards contain all required items and that test equipment is in a safe
operating condition. The completed checklist should be retained on file for at least one year.
Electric Shock. An electric shock is the passing of an electric current through a
person. The amount of damage depends on the level of voltage and the amount of current to
which the person is subjected.
a) Voltages between 200 and 1000 volts at commercial power line frequencies are
particularly harmful since under these conditions heart muscle spasm and paralysis of the
respiratory center occur in combination. However, lower voltages can also prove fatal, as
evidenced by records of deaths caused by 32-volt farm lighting systems. The body response to
current is as follows: 5-to-15 mA stimulates the muscles; 15-to-19 mA can paralyze the muscles
and nerves through which it flows; 25 mA and above may produce permanent damage to nerve
tissues and blood vessels; and, 70 mA and above may be fatal.