Recently, we have received a request to arrange lightning protection for a mall terrace wherein a canteen will be located. Certainly, it is always correctly to consider the building entirely and provide an integrated lightning protection, but when the customer only has a part of the structure, we have to deal with it.
To provide the lightning protection for the terrace, we used two 7 m lightning rods attached to the wall. We could install the rods at the distance of about 5 m beyond the terrace; therefore, they do not affect the appearance and reduce the hazards of the lightning current flowing along the current collector.
We are going to study the proposed solution for the terrace lightning protection.
Task
To calculate the lightning protection for the terrace.
Solution
Calculations of the terrace lightning protection are made in conformity with the following documents:
- "Electrical Installations Code" (hereinafter referred to as the EIC), 7th edition.
- "Instructions for the installation of lightning protection of buildings, structures, and industrial communications" SO 153-34.21.122-2003 (hereinafter referred to as SO).
- "Instructions for mounting the lightning protection of buildings and structures" Working Documentation 34.21.122-87 (hereinafter referred to as the RD).
The lightning arresters are used to protect the terrace against lightning strikes. Lightning discharger consists of an interception rod, intercepting a lightning discharge, the main conductor cable, and the ground electrode. All these elements let us divert lightning current into the ground safely, without any damage to the protected facility.
The terrace belongs to conventional facilities in terms of lightning protection according to SO and to Category 3 according to RD.
Description of the terrace lightning protection system
A set of arrangements ensuring compliance with the lightning protection requirements is based on the following solutions:
- Installation of 2 x 7 m lightning rods is carried out by attachment to the wall. It is taken into account that 1.5 m of the height of interception rods are necessary for mounting.
- Two current collectors are arranged from each lightning arrester using a zinc-plated wire D = 8 mm. The main conductor cables are mounted (with mounting step 0.6-1 m):
- to the walls using clamps GL-11703A;
- to the roof using clamps GL-11711.
A set of measures to ensure the requirements for the grounding arrangement is based on the following solutions:
- Installation of a grounding arrangement consisting of a horizontal electrode (steel zinc-plated strip having cross-section 4 x 30 mm), depth 0.5 m, distance to the foundation 1 m, and 3 vertical electrodes 3 m long (rods made of zinc-plated steel having diameter 16 mm).
- The connection of vertical and horizontal electrodes between each other is made using clamp ZZ-005-064.
- The connection of the current collector with the terminal of the zinc-plated ground bar is performed using control clamp GL-11562A.
- The design of the grounding arrangement corresponds to clause 1.7.55 of EIC Grounding arrangements for protective grounding and grounding for lightning discharges are common.
The location of the elements of the lightning protection system and the grounding arrangement is shown in Figure 1. The depicted protection area corresponds to area B, constructed as per Appendix 3 of WD.
Picture 1. Layout of the terrace lightning protection system
Условные обозначения - Key
Components of the terrace lightning protection system
Do you have any questions about grounding and lightning protection of the terrace? Please, contact the ZANDZ Technical Center!
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