Electricity + Control January 2017

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EARTHING + LIGHTNING PROTECTION
Structures with external lightning protection and
insufficient separation distances
Lightning protection systems where adequate separation distances
cannot be maintained, should be protected as follows:
• LPS in accordance with lightning protection level
• Surge protection by means of Class 1 lightning arresters and
Class 2 and 3 surge arresters
• Equipotential bonding by means of 16 mm² copper conductors
or 50 mm² aluminium conductors
When the correct separation distances cannot be establishment the
PV systems are vulnerable to partial lightning currents, therefore the
protection of inverters and data systems is done by means of Class
1 lightning arresters and not Class 2 surge arresters. In accordance
with Supplement 5 of IEC 62305-3 [2] all of the PV lines entering the
building from the outside (i.e. roof) must be protected by means of
Class 1 lightning current arresters.
In many cases, rooftop PV systems are installed on top of steel
roofs, here the separation distances cannot be maintained due to the
type of structure. In all cases where the separation distance cannot
be maintained, then all of the metal components of the PV system
must bonded directly onto the external lightning protection. It is still
imperative that an air termination system be installed to protect the
PV system fromdirect lightning strikes in order to provide a controlled
interception and dissipation of the lightning current.
Conclusion
Solar power generation systems are an integral part of today‘s elec-
trical systems. They should be equipped with adequate structural
lightning protection systems, lightning current arresters and surge
arresters, thereby ensuring long-term faultless operation of these
sources of electricity.
References
[1] IEC 62305: 2010. Protection against lightning: Part 2. Risk Manage-
ment.
[2] IEC 62305: 2010. Protection against lightning: Part 3. Physical
damage and life hazard.
Trevor Manas started his lightning protection career at Pontins in
1991 as an installation technician, learning the ropes by working on
various sites and doing physical installations. Within two years, he
was promoted to a sales engineer position, where he was involved
in site assessments, soil resistivity surveys and compiling quotations.
In 1996, Trevor was promoted to the position of director and was in charge of
ensuring the company`s compliance with the earthing and lightning protection
codes of practice. In 1999, Trevor became the managing director of Pontins. In
2013, Pontins formed a partnership with DEHN Africa.
Enquiries: Email
Isolated LPS Non-isolated LPS
25 January ‘17 Electricity+Control