Lightning is one of those natural events which catches imagination with its obvious violence and the destructive power attributed to it. Hence inconvenience to domestic, and commercial sectors.

Lightning damages to both residential and commercial premises can be various. Take a look at below diagram.

1. Lightning strikes to overhead cables , being power , communication, and data. Surge can travel whole kilometres onto this cable and enter in consumer units.

2. The surge entered through the mains cable into the distribution board. Or through the telephone line or else through terrestrial coaxial cable of Television.

3. Lightning can be to trees and nearby structures,which is in most cases. A voltage potential in the surrounding earth and soil induces a voltage to our earthing.

THE EARTH ELECTRODE

It is usually a copper or steel rod that is drilled or hammered into ground.Getting it in depth in order to get the maximum of moisture,thus less resisitance. However the resisitance varied to several conditions.

Diameter of earth rod. Depth of rod into ground. Material between rod and ground.

The idea of the earth electrode is to provide the least resistance path to ground should a lightning, or surge occur. If the resisitance is high,then the surge would try to find another path to dissipate,passing through equipment connected to wall socket receptacles.

THE RCD / RCCB / ELCB

RCD – Residual Current Device. ( Salvavita )RCCB – Residual current circuit breakerELCB – Earth leakage circuit breaker.

All the above cater for a specific purpose, that is to trip this device in case there is an earth leak of any appliance . Ratings vary and also may have delayed function. So it is important to know what type of protection you have installed in your consumer unit.

There are cases where actually the RCD is not in function !!

Either due to bad earthing connection to earth rod due to corrosion. Faulty RCD either tripping with the minimum of load or worst does not

trip.Pressing the tripped button situated on same RCD is not efficient in testing.It is the bare minimum.

RCDs fail at time due to loose wiring in same RCD connections. Appliances that are not earthed.That is keeping the round two pin plug,instead of

using the 3-pin plug.

TYPICAL LOCAL DAMAGES RELATED TO FAULTY OR NO PROTECTION

Shorted wall socket .No earth Welded/arced contacts of timer. No earth

Besides the above pictures, CCTVs, Decorders, Alarms, etc…. list never stops.

INVESTMENT IN KEEPING IN GOOD EARTH CONDITION

Regular testing of Earth Electrode . Regular testing of RCD/RCCb/ELCB. Investment in a surge arrestor. Further specific protection to PCs , telephone and Ethernet , CCTVs, etc…..

The main function of a surge protector is to provide protection against the indirect effects of lightning surges thus minimising the inrush current to the mains.