The need for a Systems Approach
As specialist consultants in the field of Earthing and its related topics, it is fortunate for us, that “inadequate earthing” is so often blamed for so many problems which range from:
Repetitive Motor Failures
Damage to electronic systems
Shocks to people
Fire and Explosions
Electrical protection schemes which fail to trip.
(The list could fill a book)
For the past 25 years we have investigated hundreds of these problems all over South Africa. The solutions to the problems have indeed “had something to do with earthing”. However looking back through our reports, there is no one common cause of problems. The only common conclusions found are the following:
There are two identical sites.
Inadequate earthing is common yet the solution has seldom been more earthing.
Surge protection is a “last resort” measure, we have seldom been forced to recommend.
There really is only one common cause of all the problems.
This is the lack of a Systems Approach.
For any design task to be successful, the designer or design group must have a clear set of OBJECTIVES to be met. This is where most of us fall down. Yes including matra.
We have wasted many engineering hours producing beautiful drawings which end up in the file 13, simply because we deviated from the primary object of the measures to be implemented. The objectives cover a broad range of disciplines and equipment. ie:
After defining all the objectives, you find your expertise is stretched from Geology and soil mechanics to software with the whole spectrum of electrical engineering in between.
Reference to Codes-of-Practice and Mil Specs do not provide all the answers because all of these have limited scope and do not form a logical or single source of reference. All too often we find that specifying compliance with Code SABS… or IEC or Mil… results in the delegation of important design decisions to those who are not qualified to make them.
This form of “passing the buck” takes place at design and implementation levels and needs to be addressed by education and training at all levels.
One must take a System Approach which must include the following steps:
Define the multitude of objectives and sort these in terms of priorities.
Identify and quantify the source of risk (of Overvoltages, EMI, static etc.)
Quantify the frequency of risk.
Consider the physical realities eg: Soil conditions, Civil layout and conductor lengths, existing electrodes and inherent screening offered by structures and enclosures.
Consider all the fortuitous conductors provided by civil and mechanical structures. From reinforcing steel mesh, pipe bridges to access flooring. All these must be exploited not only to save as money but for sound technical reasons.
Decide on the most appropriate theoretical philosophy of design. Although this is usually dictated by the equipment, there can be different types of equipment within one room which may require different theoretical design.
All of the above must be absorbed and an overall picture formed, before the design concepts can be finalized.
During the design stage, recognition of all the practical constraints is crucial. These may be obvious and unavoidable, such as constraints imposed by layout and existing structures. However most frustrating are those caused by poor workmanship. For example, cable screens you want grounded, may have been cut back and there is no slack in the cable.
The final challenge is to produce a “How To” document which a non-expert can use to implement the whole SYSTEM. This requires a lot of detailed illustrations and very specific instructions. Statements like “use the shortest” are too open-ended.
At the end, it can look so simple and obvious. You wonder why it took so long to arrive at the final design.
However this simplicity is confirmation that the design will meet the overall objectives.
Adopt a Positive Approach
Added to the System Approach we must adopt a Positive Approach. So many clients still consider lightning as one of those Acts of God which we cannot protect ourselves against.
This leads to half-baked, token efforts, based on “Just do your best”.
At the other extreme, tons of material are buried in the ground in the belief that “a good earth” will solve all the problems. Or the “shot gun” approach whereby everything is bonded to everything and/or every gadget on the market is installed in the belief “that every possible measure was taken.”
There is no reason why clients should not demand a lightning-proof installation. However, this can only be achieved by adopting a Systems Approach and lots of common sense.