Hi everybody - I've been checking in reguraly but this is the first time I jumped off the fence... so to speak.
Here is a situation I am dealing with as a maintenace electrician and I would like your opinion on it- maybe an inspector's prespective too - before I take it up to the engineer. There is this Crane bridge fed from 480 V ducto-bars through two sets of colectors on each phase. Each colector set has two shoes so we have a total of 4 shoes per phase. The wire attached by the factory to each individual shoe is # 6 and is only aobut 18 inch long, then is spliced together with a 3/0 wire. All four 3/0 wires are connected together in a J-box and from there one 3/0 wire feeds the line side of the Main breaker in the control cabinet on the Bridge (for simplicity I am only following one phase here). I found one of those # 6 wires completely bare with the insulation melted off. Could this be an illegal tap, where basically a small unprotected wire gets overloaded acting like a weak link in circut otherwise sized at 3/0? Theoretically there are situations when the small # 6 is called upon to carry the whole load (up to 200A) when for example the other 3 shoes are on a dead section of the ducto-bar. Even in a normal situation the 4 shoes are not evenly loaded given the fact that the current will follow the path of least resistence. I am thinking of replacing all these # 6 wires with 3/0 welding cable so everything will be the same size. I appreciate your comments on this and I will share them with the crew. Thank you.
