You are Never Entirely Safe from Lightning – Kenneth Oigo

[caption id="attachment_1279" align="alignnone" width="640" caption="Image coutersy of Advanced Lighting Systems, http://advancedlightningsystems.com/"][/caption]

As we all learned during our physics lessons — at least those of us who paid attention — Benjamin Franklin discovered that a lightning bolt striking an elevated grounded rod follows a path of least resistance to earth.

This discovery, if we may call it thus, advanced fire safety considerably in those days — and still holds true today.

The installation of rods — also known as air terminals because they are termination points for bolts of lightning in the air — and a series of horizontal and vertical straps or wires connected to ground rods make up the classic definition of a Lightning Protection System (LPS).

An LPS can thus be defined as a path of least resistance for lightning as it travels from the point of interception to earth.

Lightning can at times be arbitrary, random and unpredictable, and has been known to strike buildings or targets on the ground that are up to four kilometres from the lightning cloud.

As a result of recent technological advancements in the construction industry, buildings nowadays are not made of simple wooden structures as was the case in the 18th century, when the first conductors were invented.

Most modern buildings are made up of structural steel, reinforced concrete, metal claddings, steel roof framework, cast iron waste pipes, copper gas pipes in walls, cable TV wiring, telephone wiring, electrical wiring, metal door and window frames, etc.

If lightning strikes an LPS on a structure, it is possible that the high voltage electricity may be transferred to the unintended conductors listed above, posing a huge danger to all people in their vicinity.

The magnetic effects of lightning may also affect these conductors, and his poses a huge danger to phone users during thunderstorms, those taking showers during thunderstorms, washing dishes at the kitchen sink, working with electrical appliances during thunderstorms, or leaning on metal doors or windows.

Therefore, despite the fact that buildings may be fitted with lightning arresters and a sophisticated LPS, it is important to refrain from these activities to minimise the risk posed to us.

The risk from indirect lightning strikes is considerably high and, as such, the LPS is of no merit during indirect lightning strikes.

Therefore, detailed attention should be paid to bonding, grounding, and surge protection of the building and its electrical accessories.

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Source: Daily Nation