- Install a first-stage arrestor (usually a metal oxide varistor) with over 20 kA current capability between the phase and neutral lines and from both lines to a low impedance ground.
- Install a series inductor with adequate current rating on the line and on neutral conductors. Several meters of wire can also act as an inductor.
Install second-stage metal oxide varistors (over 3 kA rated) with lower voltage rating
at the equipment mains input.
Check that there are fuses or other overcurrent protectors in front of the first-stage arrestors.