This is a topic I have avoided for some time. On occasion I have had customer ask why I dont fit surge protection into the new DB's we install, my response "you dont have to install surge protection where we live".
What I have learnt from insurance claims in the past, no matter how much money you spend on "surge protection" , if the insurance company checks the weather for the day of the claim, if no lightning happened on that day, sorry for you. So you need to check your policy to make sure you have a clause in your policy which covers you for other types of high voltages surges, which could be caused by transient switching current, stolen neutral conductors, faults on the mains supply caused by transformer short circuit etc. In other words everything not lightning related.
I have had 2 requests this week to install surge protection, 1 for a factory with a 1000 amp supply required by the insurance company and the other a home owner who requested a DB replacement.
SANS 10142-1 2021 ED3.01 covers it in
Annex I
(normative where surge protection
is required or installed (see 6.7.6))
Installation of surge protective devices (SPDs) into low-voltage
systems in order to protect the installation
NOTE The installation of surge protection is not compulsory, but where it is installed or deemed
necessary by the risk assessment (or both), compliance with this annex is required.
I.1 Installation of surge protective devices (SPDs) into lowvoltage
systems
I.1.1 Surge protection
I.1.1.1 Surge protective devices (SPDs) are used to protect, under specified conditions,
electrical systems, components and equipment against various transient overvoltages
and surge currents such as lightning and switching surges. The selection, connection
and application of SPDs installed in low-voltage installations shall be in accordance with
this annex. The type and class of SPD to be incorporated in the lightning protection
design will depend on the risk assessment and protection level. The Risk assessment
needs to be carried out in accordance with SANS 62305-2 and tables Q1.1 and Q1.2 in
annex Q.
I.1.1.2 Class I surge protective devices (SPD), that comply with the requirements of
SANS 61643-11, are installed to protect an installation against partial lightning currents.
(Iimp 10/350μs) and induced overvoltages, caused by atmospheric discharges (lightning).
NOTE In order to protect against transient and switching overvoltages, , class II SPD should be
installed in conjunction with class I SPD and energy coordination between the SPDs, as per
SANS 61643-12, needs to be proved.
I.1.1.3 Class II surge protective devices (SPD), that comply with the requirements of
SANS 61643-11, are installed to protect an installation against transient overvoltages
and surge currents (In 8/20μs) caused by switching operations or induced atmospheric
discharges.
I.1.1.4 Class III surge protective devices (SPD), that comply with the requirements of
SANS 61643-11, are installed to protect an installation against switching surges and by
limiting transient overvoltages (Uoc 1.2/50μs; 8/20μs) caused by switching operations.
NOTE It is recommended that a class III SPD be used in conjunction with an energy coordinated
class II SPD.
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