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OM-166 941 Page 5
quate to carry ground currents safely. Equipment made
electrically HOT by stray current may shock, possibly
fatally. Do NOT GROUND to electrical conduit, or to a
pipe carrying ANY gas or flammable liquid such as oil or
fuel.
Three-phase connection. Check phase requirements of
equipment before installing. If only 3-phase power is
available, connect single-phase equipment to only two
wires of the 3-phase line. Do NOT connect the equip-
ment ground lead to the third (live) wire, or the equip-
ment will become electrically HOT-a dangerous condi-
tion that can shock, possibly fatally.
Before welding, check ground for continuity. Be sure
conductors are touching bare metal of equipment
frames at connections.
If a line cord with a ground lead is provided with the
equipment for connection to a switchbox, connect the
ground lead to the grounded switchbox. If a three-prong
plug is added for connection to a grounded mating re-
ceptacle, the ground lead must be connected to the
ground prong only. If the line cord comes with a three-
prong plug, connect to a grounded mating receptacle.
Never remove the ground prong from a plug, or use a
plug with a broken off ground prong.
2. Electrode Holders
Fully insulated electrode holders should be used. Do
NOT use holders with protruding screws.
3. Connectors
Fully insulated lock-type connectors should be used to
join welding cable lengths.
4. 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.
5. Terminals And Other Exposed Parts
Terminals and other exposed parts of electrical units
should have insulating covers secured before opera-
tion.
6. Electrode
a. Equipment with output on/off control (contac-
tor)
Welding power sources for use with the gas
metal arc welding (GMAW), gas tungsten arc
welding (GTAW) and similar processes nor-
mally are equipped with devices that permit on-
off control of the welding power output. When
so equipped the electrode wire becomes elec-
trically HOT when the power source switch is
ON and the welding gun switch is closed. Never
touch the electrode wire or any conducting ob-
ject in contact with the electrode circuit unless
the welding power source is off.
b. Equipment without output on/off control (no
contactor)
Welding power sources used with shielded
metal arc welding (SMAW) and similar proc-
esses may not be equipped with welding power
output on-off control devices. With such equip-
ment the electrode is electrically HOT when the
power switch is turned ON. Never touch the
electrode unless the welding power source is
off.
7. 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. Disconnect all cables from welding power
source, and pull all 115 volts line-cord plugs.
Do not open power circuit or change polarity while weld-
ing. If, in an emergency, it must be disconnected, guard
against shock burns, or flash from switch arcing.
Leaving equipment unattended. Always shut OFF and
disconnect all power to equipment.
Power disconnect switch must be available near the
welding power source.
F. Protection For Wearers of Electronic Life Sup-
port Devices (Pacemakers)
Magnetic fields from high currents can affect pacemak-
er operation. Persons wearing electronic life support
equipment (pacemaker) should consult with their doctor
before going near arc welding, gouging, or spot welding
operations.
1-4. STANDARDS BOOKLET INDEX
For more information, refer to the following standards or
their latest revisions and comply as applicable:
1. ANSI Standard Z49.1, SAFETY IN WELDING
AND CUTTING obtainable from the American
Welding Society, 550 N.W. LeJeune Rd, Miami,
FL 33126.
2. NIOSH, SAFETY AND HEALTH IN ARC WELD-
ING AND GAS WELDING AND CUTTING ob-
tainable from the Superintendent of Documents,
U.S. Government Printing Office, Washington,
D.C. 20402.
3. OSHA, SAFETY AND HEALTH STANDARDS,
29CFR 1910, obtainable from the Superinten-
dent of Documents, U.S. Government Printing
Office, Washington, D.C. 20402.
4. ANSI Standard Z87.1, SAFE PRACTICES FOR
OCCUPATION AND EDUCATIONAL EYE AND
FACE PROTECTION obtainable from the Ameri-
can National Standards Institute, 1430 Broad-
way, New York, NY 10018.