Method Statement For Lightening Protection System
- Ensure only trained persons shall operate the power tools.
- Ensure all concerned personals shall use PPE (Personal Protective Equipment) and all other safety items as required.
- Ensure adequate lighting is provided in the working area at all time.
- Ensure service area/work area openings are provided with barricade, warning tape, and safety nets where applicable.
- Check all material delivered to site is inspected properly by QA/QC Engineer and check if it is stored properly as per manufacturer’s recommendations.
- Work shall be carried out by the site staff under strict supervision and guidance of the concerned supervisors. The electrical engineer shall check all the lightening protection system installations are as per the installation check list.
|Hacksaw Frame and Blade|
|Sand Paper and Files|
|Meggar for earth testing|
|Exothermic welding tool kit|
Material Storage & Handling
On receipt of the Lightning Protection System materials at site necessary precautions shall be taken for unloading, shifting and storage, as follows:
- Material shall be stored in a covered / dry space at all the time to avoid being damaged.
- All materials received at site shall be inspected and ensured that the materials are as per approved material submittal.
- Any discrepancies, damage etc., found will be notified and reported for further action.
- Material found not suitable for site use will be removed from site immediately.
Lightening Protection System Installation Sequence
The installation team shall use 25 x 3 mm copper tape to form the air-termination mesh on the uppermost part of the building structure i.e. roof. Complete tape network shall be bonded to all down conductors around the periphery and a branch conductor to be taken horizontally and all these down conductors to be bonded by using approved clamps.
- Number of down conductors shall be based on the technical calculation or shop drawings.
- When different metal to be connected a bimetallic clamp shall be used.
- Any roof (e.g. staircase) on top of the main roof shall have air termination network and it shall be connected to lower roof network.
- The DC earth tape clamp shall be fixed on the route as shown in the approved shop drawings and the straightness shall be checked along with building finish, on the top roof high level.
- All the fixing clips for the copper tape shall be metallic (complying with Class ‘H’ of the electrical testing based on BSEN 50164) and shall be fixed at an interval of 1000 mm fixing distance for fixing conductors on vertical surface up to 20m from the ground level and on the horizontal surface i.e. roof.
- The down conductors shall be placed around the building as per approved drawing.
- A minimum of two re-enforcing bars shall be used as down conductors in each column.
- The minimum overlap dimension to connect two re-bars shall be at least 20 times the diameter of the re-bar.
- If it not practical to arc-weld two re-bars then suitable clamps should be used at a distance of each 10cm till the above dimension is achieved.
- Re-enforcement bars in the designated columns should be used as down conductors, with a suitable junction box to be recessed at approx. 1000 mm above the finished paving level for the test link.
- The electrical continuity of the reinforcing bars shall be determined by electrical testing between the uppermost part and the ground level.
- The overall electrical resistance should not be greater than 0.2 Ω, measured using test equipment suitable for this purpose. If this value is not achieved, or it is not practical to conduct such testing, the reinforcing bar shall not be used as a natural down conductor.
- Bond each copper down conductor throughout its length to the building reinforcement bar with spacing not more than 1.5 meter. All bonding to reinforcement bar shall be by using manufacturer’s standard materials and tools for the same.
- Thermo weld all connections between cables, aerial terminals and ground rods. Compression type connectors may be used where approved by the consultant.
- The earthing shall be done as per local authorities requirements.
- A minimum of 2400 mm copper electrode shall be provided with each down conductor separately and the number of earth rods in each earth pit shall be decided based upon the calculations. Wherever the soil resistivity is low (typically below <20 Ω /m), use either copper rods or stainless steel rods to ensure the longitivity of the earth termination network.
- Measure the resistance of the complete installation and submit for review to consultant/client.
- The complete Lightning Protection System measured at any point, should not exceed 10 ohms. With the test clamp disconnected, the resistance of each individual earth should be no more than ten times the number of down conductors in the complete system.
- The terminated head of each electrode shall be located in a light weight inspection pit. If clear earth is not available, then the Specialist Lightning Protection Installer has to install the earth pit inside the building using double flange earth electrode seals.
- Test clamps shall be provided in each inspection pit to allow for testing and commissioning.
- Concrete inspection pits with cover shall be installed flush with finished floor level and be fully accessible.
- All metallic parts protruding outside the extended air termination network (e.g. balcony hand rails etc) shall be connected to the air termination using suitable clamps (material complying to BSEN 50164) at every floor wherever the horizontal conductor is applied.
- The equipments on the roof shall be protected using vertical air terminals of suitable height so that it provides the zone of protection. This air terminal shall be installed at a suitable separation distance so that the partial lightning current doesn’t flow through the equipment as per approved shop drawing. The cable from the equipment shall be protected using an over – voltage protector.
If required to do the furse welding then you can check this method statement for furse welding.
Testing Of Lightening Protection System
- On completion of the installation the following isolated and combined measurement and / or checks has to be made and the results recorded in a lightning protection system checklist.
- The resistance to earth of each local earth electrode and in addition the resistance to earth of the complete earth termination system.
- Each local earth electrode has to be measured in isolation and the test point between the down conductor and the earth electrode in the disconnected position (isolated measurement)
- A further measurement has to be taken with the test point in the connected position (combined measurement)
- The results of visual check of all conductors, bonds and joints and their measured electrical continuity.
- If the resistance to earth of a lightning protection system exceeds 10 ohms, the value must be reduced. Necessary remedial action needs to be taken to reduce the value below or equal to 10 ohms.