Impax IM-MMA140 Instruction Manual page 5

SAFETY INFORMATION
Sweat, sea water, or moisture between body
and an electrically LIVE part - or earthed metal -
reduces the body surface electrical resistance,
enabling dangerous and possibly lethal currents
to flow through the body.
Earthing the Equipment
When arc welding equipment is earthed
according to the National Electrical Code, and
the workpiece is earthed, a voltage may exist
between the electrode and any conducting
object.
Examples of conducting objects include, but are
not limited to, buildings, electrical tools, work
benches, welding power source cases,
workpieces, etc.
Never touch the electrode and any metal object
unless the welding power source is off. When
installing, connect the frames of each unit such
as welding power source, control, work table,
and water circulator to the building earth.
Conductors must be adequate to carry earth
currents safely. Equipment made electrically
LIVE by stray current may shock, possibly
fatally. Do NOT EARTH to electrical conduit, or
to a pipe carrying ANY gas or a flammable liquid
such as oil or fuel.
Electrode Holders
Fully insulated electrode holders should be
used. Do NOT use holders with protruding
screws or with any form of damage.
Connectors
Fully insulated lock-type connectors should be
used to join welding cable.
Cables
Frequently inspect cables for wear, cracks and
damage. IMMEDIATELY REPLACE those with
excessively worn or damaged insulation to avoid
possibly lethal shock from bared cable. Cables
with damaged areas may be taped to give
resistance equivalent to original cable. Keep
cable dry, free of oil and grease, and protected
from hot metal and sparks.
Terminals And Other Exposed Parts
Terminals and other exposed parts of electrical
units should have insulating covers secured
before operation.
Electrode
Equipment With Output On/Off Control
(Contactor)
Welding power sources for use with the gas
metal arc welding, gas tungsten arc welding and
similar processes normally are equipped with
devices that permit on/off control of the welding
power output. When so equipped the electrode
wire becomes electrically LIVE when the power
source switch is ON and welding gun switch is
closed. Never touch the electrode wire or any
conducting object in contact with the electrode
circuit unless the welding power source is off.
Equipment Without Output On/Off Control
(No Contactor)
Welding power sources used with shielded
metal arc welding and similar processes may
not be equipped with welding power output
on/off control devices. With such equipment the
electrode is electrically LIVE when the power
switch is turned ON. Never touch the electrode
unless the welding power source is off.
Changing Electrodes
In MMA (Manual Metal Arc) welding, the
electrode holder should be isolated when
changing the electrode, where a work piece is
earthed. If the electrode is changed without
isolating the electrode holder, the welder is
relying on the insulation properties of the glove
to avert shock from the OCV (Open Circuit
Voltage) which can be 80V between the
electrode and earth. If the glove is wet, the
electrode a bad insulator or the welder in
contact with a conductive surface, one or more
of these layers of insulation may be ineffective.
Safety Devices
Safety devices such as interlocks and circuit
breakers should not be disconnected or shunted
out. Before installation, inspection, or service of
equipment, shut OFF all power and remove line
fuses (or lock or red-tag switches) to prevent
accidental turning ON of power. Do not open
power circuit or change polarity while welding. If,
in an emergency, it must be disconnected,
guard against shock burns, or flash from switch
arcing.
Always shut OFF and disconnect all power to
equipment. Power disconnect switch must be
available near the welding power source.
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