*The secondary lightning rod (wire) prevents direct lightning strikes from damaging buildings, while the secondary lightning arrester prevents induced lightning from damaging electrical equipment; Third level equipment lightning protection to prevent lightning induced interference with electronic devices * Second level lightning protection, which is familiar to everyone; The third level lightning protection is little known.

The third level equipment lightning protection, using anti electromagnetic dry RAO devices to prevent lightning induction interference, is a new technology field called "electromagnetic compatibility". An "anti electromagnetic dry RAO device" can be used. It can absorb electromagnetic interference and convert it into heat for consumption. It can independently eliminate industrial interference of several thousand volts, making the anti-interference degree of intelligent products reach the highest standard without grounding, thus rejecting lightning induction interference.

The third level protection for lightning protection generally involves installing a first level lightning arrester in the main distribution, selecting an SPD with a relatively large current capacity (80KA~160KA depending on the situation), then installing a second level lightning arrester (10KA~40KA) at the distribution box in the subordinate area, and finally installing a third level signal lightning arrester at the front end of the equipment.

The installation of SPD (lightning arrester) requires a nearby grounding flat iron at the installation location, so that lightning waves can be quickly released when passing through the lightning arrester. The grounding resistance needs to be below 1 ohm, and in some areas there are special regulations that can be relaxed to below 4 ohms because voltage limiting SPDs are generally used, so the length of the line between them should not be less than 5 meters.

The third level protection for lightning protection generally involves installing a first level lightning arrester in the main distribution, selecting an SPD with a relatively large current capacity (80KA~160KA depending on the situation), and then installing a second level lightning arrester (10KA~40KA) at the distribution box in the subordinate area, followed by installing a third level signal lightning arrester at the front end of the equipment. The installation of SPD (lightning arrester) requires a nearby grounding flat iron at the installation location, so that lightning waves can be quickly released when passing through the lightning arrester. The grounding resistance needs to be below 1 ohm, and in some areas there are special regulations that can be relaxed to below 4 ohms because voltage limiting SPDs are generally used, so the length of the line between them should not be less than 5 meters.