With industrial premises of any age there are normally a variety of problems that are evident. The original main supply and various other circuits tend to be wired in VIR (vulcanised impregnated rubber) cables. Over a period of years other circuits are added; normally with no design criteria observed and eventually the new circuits are added to compiling the problem.
Although it has always been necessary to test circuits as they are installed it was not common practice in the past. Most circuits were installed using a “rule of thumb” method where certain cable sizes were used for certain types of circuit, not taking into account the volt drop or Zs (circuit impedance).
When testing industrial premises that have not undergone such a procedure we recommend that the whole of the system is inspected and tested and a report compiled on the condition of the installation.
Within the report will be a list of Observations and Recommendations required to bring the system in line with BS7671 IEE Regulations 16th Edition (17th in 2008).
Once the deviations from the regulations are attended top a “Satisfactory” report will be issued.
Any test results for new installations should be added to this report until it is due for a re-test (see chart).
If this situation is adhered to; on the anniversary of the re-test, the company compiling the test report will be able to “sample test “a percentage of the system therefore making the procedure less expensive.
