Companies and organisations are increasingly becoming aware of the effects of lightning and other phenomena which cause overvoltage surges and the risk posed to buildings, equipment and their personnel. The effects do not have to be violent as expected from a direct strike. A lightning strike some miles away will induce surge voltages in electronic equipment and damage it or corrupt the data contained in it. In some cases personnel using the equipment may get an electric shock making them uncomfortable in their job.
Companies very often take some measures to provide protection but this usually takes the form of some ‘off the shelf’ device which is not up to the expected threat and in any case degrades with time.
To ensure that an organisation is aware of the risk posed to their particular situation Surgetech is able to carry out risk assessment surveys to the British Standards Institute Code of Practice regarding complete sites, buildings, equipment and personnel. Surgetech has worked to both the existing BS 6651 Standard and the new BS EN 62305 Lightning Protection Standard.
A comprehensive report is issued detailing the level of risks and where they are. The company is then aware of the situation and can make its own judgement as to what it should do – it can obtain independent quotation to carry out any work required – it can obtain further information from Surgetech regarding the costs of providing protection if any is required – or it can do nothing.
Soil Resistivity Measurement
New buildings and existing structures such as electricity sub-stations need to be well earthed and it is important therefore to know something of the soil resistivity and how it varies with depth over the site. This allows earth rods to be placed to minimise the impedance of the earthing sytem.
Surgetech normally use the Wenner (or “four electrode”) method to obtain resistivity values at different depths.