In a wire mesh welder many welds are made at virtually the same time. The wire is in contact with the machine, fixtures and electrodes in many places. It is important that the current goes through the weld and not stray through the fixture or machine components. The most important step is machine design. It is imperative that all of the fixtures and support structure of the machine be electrically insulated and nonconductive. This is a machine design issue. The resistance of the wire will retard that flow but the goal is to have a designed path for the flow not a random path.
Secondly all machines should be properly grounded and or have the correct safety devices installed and functional. If a floating secondary is present a ground reactor will be employed for AC or a ground resistor for MFDC. The ground reactor is attached to both the positive and negative pads and is center tapped to ground. If the secondary voltage exceeds its reactors rating it immediately will flow all current to ground and trip the breaker. The ground resistor works in a similar fashion for the MFDC system except it only connects the negative pad to ground.
Proper electrical grounding is very important and should be performed by personnel familiar with the equipment and safety requirements necessary. Contact a machine builder, reputable distributor or facility engineer.
References: RWMA – Resistance Welding Manual 4th Edition
AWS – AWS J1.2 - Guide to the Installation and Maintenance of Resistance Welding Machines