Abstract: The invention relates to electric arc processes particularly for underwater use. Electric arc processes effected under water ordinarily operate at a voltage of 20 or 30 volts, with an open circuit of e.g. 50 volts, and are at a level that does not pose a serious risk to the diver. Such as plasma arc cutting has typical voltages of 100-200 volts, and an open circuit voltage of 200-400 volts, and can put a diver at considerable risk of electric shocks at a level that can be life threatening. The object of the invention is to avoid such risks, an objective met by electric arc equipment comprising an earthed safety electrode strategically positioned close to the torch of the electric arc equipment, to create the closest earth to which current could flow, but without the striking of an arc between a torch electrode and the earthed safety electrode.

Abstract: The invention relates to plasma arc apparatus. In plasma arc apparatus it is known to provide a torch, there being provided within the torch an electrode suitably connected to a source of supply, and there being the provision for the passage of gas through the torch and through a nozzle on the torch and for the supply of coolant to reduce the temperature of the electrode and the nozzle during use.