http://www.lincolnelectric.com/assets/servicenavigator-public/lincoln3/imt237.pdf
• Do not touch electrically hot parts.
Input Power and Grounding Connections
Before starting the installation, check with the power company to be
sure your power supply is adequate for the voltage, amperes, phase
and frequency specified on the welder nameplate. Also, be sure the
planned installation will meet the United States National Electrical
Code and local code requirements. This welder may be operated
from a single phase line or from one phase of a two or three phase
line.
All models designed to operate on less than 250 volt input lines are
shipped with the input cable connected to the welder.
Place the welder so there is free circulation of air in through the
louvers in the back and sides of the case and out of the bottom on
all four sides. Mount a NEMA Type 6-50R receptacle in a suitable
location. Be sure it can be reached by the plug on the input cable
attached to the welder.
Using the following instructions, have a qualified electrician connect
this receptacle (NEMA 6-50R Type) to the power lines at the fuse
box. Three #10 or larger copper wires are required if conduit is
used. For long cable runs over 100'(31m), #8 or larger wire in
conduit will be needed to prevent excessive voltage drops. Fuse the
two hot lines with 50 ampere super lag type fuses as shown in the
following diagram. The center contact in the receptacle is for the
grounding connection. A green wire in the input cable connects this
contact to the frame of the welder. This insures proper grounding of
the welder frame when the welder plug is inserted into the
receptacle. If a separate disconnect switch is used, it should have
two poles for the two hot lines and both should be fused for 50
amperes.