What calibration actually checks
Calibration and validation to BS EN IEC 60974-14 measures what a welding power source really delivers (current, arc voltage and, for MIG/MAG, wire feed speed) against traceable reference instruments, and compares it with what the machine's display or settings say.
The standard sets two accuracy grades: standard grade, for manual and semi-automatic welding, and precision grade, for mechanised and automated welding where tighter control matters. The certificate tells you whether the machine meets its grade.
BS EN IEC 60974-14 replaced the older BS EN 50504, so if your paperwork still quotes 50504, it's worth asking why.
How often
The standard doesn't set a fixed interval. In practice, annual calibration is what most quality systems, customers and auditors expect.
If you work to ISO 3834 or EN 1090, your welding procedures depend on the parameters on the machine being right. An out-of-date or missing calibration certificate is one of the easiest findings an auditor can raise.
When to check sooner
- After any repair that touches the power circuit or control boards.
- If a machine has been dropped, flooded or damaged.
- If welders notice it behaving differently, or weld quality changes for no obvious reason.
- Before a new contract or audit, if the last certificate is close to running out.
What you should get
A certificate per machine showing the readings taken, the grade and the result, plus a sticker on the machine with the next due date. If a machine fails, you should be told why and what it will take to put right.