Subscribe to our newsletter to receive the latest news and events from TWI:

Subscribe >
Skip to content

Legislation with far reaching effects

Connect, no. 137, July/August 2005, p.8

Measurement of the magnetic field close to the electrodes of a resistance welding machine
Measurement of the magnetic field close to the electrodes of a resistance welding machine

The Physical Agents Directive to be introduced in April 2008 will have a major impact on manufacturers, operators and users of welding and non destructive testing equipment and installations where exposure to electromagnetic radiation needs to be considered.

The directive places a range of duties on employers, the most significant of which are:

  • To assess and measure levels of electromagnetic fields (EMFs) to which workers are exposed
  • Where these levels exceed 'action values', to assess whether exposure limits are overstepped
  • To ensure that exposure limits are not exceeded
  • To erect warning signs where EMF levels may cause exposure limit values to be exceeded
  • To provide appropriate information and training

The main processes believed to produce significant EMFs are;

  • Resistance welding
  • Some arc welding processes
  • High frequency welding processes as used in plastics
  • Magnetic particle inspection
  • Processes using high currents at AC or higher frequencies, eg induction heating

TWI has experience of carrying out and interpreting the results of electromagnetic field measurements and has recently carried out a project for the HSE, see www.hse.gov.uk/research/rrhtm/rr338.htm

TWI can advise companies on the risks from welding processes, guidance on minimising exposure and whether a workplace assessment is required.

For further information please contact Geoff Melton at TWI. E-mail: geoff.melton@twi.co.uk

For more information please email:


contactus@twi.co.uk