Plasma cutters use a number of methods to start the pilot arc, depending on the environment the unit is to be used in and its age. Older cutters use a high voltage, high frequency circuit to start the arc. This method has a number of disadvantages, including risk of electrocution, difficulty of repair, sparkgap maintenance, and the large amount of radio frequency emissions. Plasma cutters working near sensitive electronics, such as CNC hardware or computers, use the contact start method. The nozzle and electrode are in contact. The nozzle is the cathode, and the electrode is the anode. When the plasma gas begins to flow, the nozzle is blown forward. A third, less common method is capacitive discharge into the primary circuit via a Silicon Controlled Rectifier.

especially those without power factor correction, cannot be run from a generator. However newer models have internal circuitry that allow units withour power factor correct to run on generators.

The HF Contact type typically found in budget machines uses a high frequency high voltage spark to ionise the air through the torch head and initiate an arc. The arc can only be formed if the torch is in contact with the job material. HF Contact type machines are not suitable for applications involving CNC cutting.