Hi All, Another request for advice from any electrical experts please. Works are ongoing for the removal and replacement of electrical cables leading to multiple equipment. Electrical contractor has been employed and in charge of the work. The plant is very old and all the 230v cables are not ID or recorded on electrical drawings. Our site engineers have worked closely with them to identify cable locations back to MCC panels. However it has be discovered that one cable (out 84) had previously been installed back to a different panel then thought. The main panel was isolated and LOTO and all cables tested prior to work. However a day or two later one cable (that was previously wired to another Panel that no one was aware of) became live and arced to a metal guard cover on a pump motor. Its power source must have been returned to power but i must stress the panel that supplied the cable was not believed to have been the source for the cable. No injuries but a seriously dangerous near miss occassion. Now my question is why the contractor (experience & competent) did not request that all these cables that were not identified by drawings were not phyiscally traced back to its source as part of the works. Would this be a common approach you would expect from an electrical contractor doing this type of work? I'm not trying to find blame here but I want to know if these controls we are recommending to be part of our procedures going forward should have been the normal approach for an experienced and competent electrical contractor? Thanks for your help,

Safetyman2010, I believe that the approach was reasonable considering that there were as i read your post 87 cables. However, there was an issue and you need to get to the route cause. There are a few issues here, in that any previous works undertaken should have been recorded and certificated. Within reason the cables should have been physically traced back to their origin, however, this can be very time consuming & difficult. Are the contractors experienced in this type of work? I think that your plane personnel should perhaps have been able to assist more accurately in identifying the wiring? Perhaps it would have been better to "live" or "functionally" isolate the equipment, e.g. prior to starting any works whilst the equipmet was still functioning, & in a safe operational state, isolate the equipment whilst operational, that way, it would be known which equipment shut down and which did not, thus that the eqipment was actually fed from that isolation device. Then go on to your LOTO procedure. Will have a little more of a think