OSHA 10 Hour Construction
For example, portable
circular saws must be
equipped with guards. An
upper guard must cover
the
entire blade of the
saw. A retractable lower
guard must cover the
teeth of the saw, except when it makes contact with the work
material. The lower guard must automatically return to the covering
position when the tool is withdrawn from the work.
Safety Switches
The following hand-held powered tools
must be equipped with a
momentary contact "on-off' control switch: drills, tappers, fastener
drivers, horizontal, vertical and angle grinders with wheels larger
than 2 inches in diameter, disc and belt sanders, reciprocating
saws,
saber saws, and other similar tools. These tools also may be
equipped with a lock-on control provided that a single motion of the
same finger or fingers that turn it on can accomplish turnoff.
The following hand-held powered tools may be equipped with only
a positive "on-off' control switch: platen sanders, disc sanders with
discs 2
inches or less in diameter; grinders with wheels 2 inches or
less in diameter; routers, planers, laminate trimmers, nibblers,
shears, scroll saws and jigsaws with blade shanks 1 ¼” wide or
less.
Other hand-held powered tools such as
circular saws having a
blade diameter greater than 2 inches, chain saws, and percussion
tools without positive accessory holding means must be equipped
with a constant pressure switch that will shut off the power when
the pressure is released.
Electric Tools
Employees using electric tools must be aware of several dangers;
the most serious is the possibility of electrocution.
Among the chief hazards of electric-
powered tools are bums and
slight - shocks which can lead to injuries or even heart failure.
Under certain conditions, even a small amount of current can result
in fibrillation of the heart and eventual death. A shock also can
cause the user to falloff a ladder or other elevated work surface.
To protect the user from shock, tools must either have a three-wire
cord
with ground and be grounded, be double insulated, or be
powered by a low-voltage isolation transformer. Three-wire cords
Hand and Portable Power Tools
Page 5
OSHA 10 Hour Construction
contain two current-carrying conductors and a grounding conductor.
One end of the grounding conductor connects to the tool's
metal
housing. The other end is grounded through a prong on the plug..
Anytime an adapter is used to accommodate a two-hole receptacle,
the adapter wire must be attached to a known ground. The third
prong should never be removed from the plug.
Double insulation is more convenient. The user and the tools are
protected in two ways: by normal insulation on the wires inside, and
by a housing that cannot conduct electricity to the operator in the
event of a malfunction.
These general practices should be followed
when using electric
tools:
•
Electric tools should be operated within their design limitations.
•
Gloves and safety footwear are recommended during use of
electric in case of breakage.
•
When not in use, tools should be stored in a dry place.
•
Electric tools should not be used in damp or wet locations.
•
Work areas should be well lighted
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