Saturday 2 November 2013

A Real Challenge for Lightning Protection Designers


Situated 160 km from the Capital of Sri Lanka, Kandalama Heritage is one of the most picturesque five star hotels in the world. When we were contracted for designing the Lightning Protection system to the hotel, we were delighted as it will give us the chance to adventure one of the world’s top most holiday resorts. 

However, as we get into the work in evening of our first day there, we understood that our task is not that easy. The hotel is 1 km in width, with two wings expanding symmetrically from the Center lobby. The back side of the building is a solid rock for the entire one kilometer stretch. Some parts of the rock were included into the building even at the lobby area. 

The front is open to the sedate Kandalama Lake, where even wild elephants take a swim once in a while. Rest is thick green forest giving home to many wild animals from stags and deer to leopards and bears. The hotel is almost completely camouflaged with various green plants on the walls and at roof top gardens. 

There were several layers of the building. At each layer a large roof top garden has been designed and I rank that segment as the best part of each floor level. At the apex of the hotel, an ESE air termination was situated (at the middle of the top-most roof terrace) giving false security to the visitors and staff to use the terrace even during overcast conditions. Largely exposed outdoor swimming pools were situated at three levels. At several levels, parabolic antennas, coolers and electrical motor housings were installed at the roof top.

Our task of designing the LP system was really tough due to several reasons. Designed by the best architect that Sri Lanka has produced so far, Geoffrey Bawa, the management was strongly reluctant to see any detectable modification to the building due to the LP system.  Effective grounding on the backside was extremely difficult (almost impossible) due to the presence of the rock. Layered segments made it extremely difficult to stretch down conductors with small number of bends.  And above all the management was very concerned about the cost (fair enough as they have already spent on consulting us). 

The cost, impact on esthetic appearance, absence of pollutants or sea breeze made us select aluminium as the alloy for down conductors. Metallic parts at the roof top levels were used as much as possible for air-terminations (provided that the dimensions of such satisfy the conditions set forth by IEC 62305-3: 2006). Such parts were metal, railings, metal roofs etc. Wherever such natural components were available, we designed air terminations based on Mesh method so that the conductors were hardly seen at lower levels. Almost the entire air-termination network, whether it is aluminium conductor system or natural component, was integrated into a single mesh. 

Although we preferred interconnecting the air-termination system with steel reinforcement of the building at roof level, the management objected for such design. However they allowed such integration close to ground level. Each down conductor was ended up with an earthing system of copper tapes/rods. The grounding system was divided into three segments and in each segment the earthing pits were interconnected by copper (forming semi ring earths). There was no feasible method to integrate the three segments together due to strategic reasons. 

All metallic parts that could be touched by a visitor or staff during a thunderstorm were adequately separated from the LPS. Other such metal parts were integrated into the LPS. We have also recommended a set of coordinated SPDs to the building. 

The only expectation of the management that we could not satisfy was the “implementation of an LPS to protect visitors and staff who use open pools and roof top terraces during thunderstorms”.  So far, there are no such scientifically proven systems or techniques invented in the world. As a highly responsible and respected company, we could not (and will not) deceive our client.

1 comment:

  1. Thank you for your information. It was very easy to understand. You are expressing it in easy way. The images are very helpful. A very useful blog on lightning protection System, I am having this device in my home and also at my office.