Why welding sets are different
A welding power source has a mains side and a welding output side. A PAT test is designed for ordinary portable appliances and looks at the mains side. The hazards specific to welding, like the voltage across the output when the machine isn't welding, aren't part of an ordinary PAT test.
BS EN IEC 60974-4 is the standard for periodic inspection and testing of arc welding equipment in use, and after repair.
What 60974-4 covers
- A visual inspection of the machine, leads, plugs and connections.
- Protective conductor continuity.
- Insulation resistance, including between the mains and welding circuits.
- Leakage current.
- No-load voltage on the welding output, and a functional check of any voltage reducing device.
Who should do it
The standard says tests should be done by an expert, meaning someone with the training, experience and knowledge of the equipment to judge the work and the hazards. Opening the machine is for expert test personnel only. Under the Electricity at Work Regulations, the person doing the work must have the technical knowledge or experience to prevent danger, or be properly supervised.
What about engine-driven welders?
60974-4 doesn't apply to engine-driven power sources. Those need their own inspection, covering both the engine and the welding side.