Download The “shocking truth” – surge protection Lightning damage and

The “shocking truth” – surge protection
Lightning damage and resultant claims – is there a cure?
Etana says a resounding YES! Did you know that by fitting an Etana-approved surge protection
device that you could prevent a significant amount of damage (and therefore claims) emanating
from lightning and surge damages – as much as up to 80% or 90%? The only reason it is not
100% is that the surge protection device that we are talking about is designed to prevent
damages as a result from surges on power cables only and not data cables. So any equipment
connected to power cables can have damages significantly reduced while those on data cables
may still be vulnerable but only via the data cable and not the power cable. There are solutions
for those as well, however.
So what is the lightning hazard and how does it cause damage?
Surge protection is not designed to prevent any physical damage from a direct strike, but there
is not really a need for this as the chances of a direct lightning strike are rare: The chance of a
direct strike to a large home (400 m2) is about 1 in every 250 years. Surge protection is
predominantly provided to prevent damage as a result of surges in the electrical system.
How do surges occur?
The most common over-voltage conditions occur as a result of:
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Utility switching
Isolation arching
Electrical motor cycling
Lightning
Lightning damage accounts for about 65% of all over-voltage damage to electrical distribution
networks in South Africa and is the chief cause of over voltage. When lightning strikes an area it
results in the creation of an electromagnetic field, which travels outwardly over a long distance.
Lightning’s danger rating is measured in lighting strikes per square kilometre. This magnetic
field creates most of the problems associated with lightning damage (besides a direct strike of
course). One to three strikes per m2 is considered a low hazard, four to seven strikes per m2 is
considered a medium hazard and anything above seven strikes per m2 is considered a high
hazard.
Some examples of areas that exhibit a high hazard according to the Council for Scientific and
Industrial Research stats below are: Johannesburg (7.5 strikes per m2), Pretoria (7.5 strikes per
m2), and Piet Retief, which has 11.3 strikes per m2.
Look at the graph below to see what the induced voltages are in relation to a lightning strike.
This graph basically indicates when a strike occurs that the surge can travel as far as 10
kilometres from the strike, though the likelihood of damage to equipment at that distance is
extremely low. The chance of damage to equipment when the strike is just 1km from the direct
strike area starts being a cause for concern, and if the strike happens just 100 metres away, the
electromagnetic field reaches 11 000 volts – which makes the chances of damage high.
This voltage is the same amount of electricity commonly found in sub-stations (11kV) and which
can supply large industrial premises with electricity.
Why are we concerned when the over voltage starts exceeding 1000v?
Lightning experienced in South Africa seldom exceeds 40kA (40 000 amps), which is a lot of
amps. The surge protector is designed to withstand up to 40kA. But just a very small amount of
over-voltage can cause damage to equipment, as the following graph shows:
From this table you will see that most equipment in your home is designed to withstand over
voltage up to 1500 volts and anything above this WILL cause damage. In industrial and
commercial properties, it is likely that any over voltage exceeding 2500 volts WILL cause
damage.
What can prevent this damage? You guessed it – an approved surge protection device!
The surge-protection device is fitted into the main DB Board (see picture below) – you only need
one device. The approved protection device does not allow any voltages higher than 1000 volts
to pass into the main electrical reticulation and rather diverts this “excess” voltage to earth. This
means that normal operations continue while the surge protection device has diverted the over
voltages through earth. This device suffers no damage unless more than 40kA (40 000 amps)
surges through it, though, as pointed out earlier, the chances of a surge higher than 40kA are
minimal.
The approved devices Etana is suggesting you install are known to operate without fault for 10
years and longer. The device has a mechanical flag (green flag for go and red flag for stop) that
indicates to you when the surge arrestor is no longer functional or has sustained damage.
Therefore, a routine monthly visual inspection of the status of the surge arrestor should be
carried out.
So what does this cost?
An Etana-approved surge-protector will cost less than a few thousand Rand – probably
cheaper than the cost of your excess!