Busbar & Tap off box - power loss & Over-voltage issues

[Simonslimline]

You ought to check whether the busbars are actually correctly connected to the lines and neutral but it is the tap off box which is incorrectly wired to the busbars ie: Black, Grey and Blue (- if Brown is correctly terminated you would expect to see the Black on the second from left and then Grey which your image does not show ). The isolator might be switching the neutral feed which is not intended. You'd get some odd voltages if this was the case AND A DANGEROUS SITUATION.

The last job i was on had some crappy legrand busbar system installed throughout the multi story carpark and main building. The connections were, L1-N-L2-E-L3 Where the SWA,s terminated in to the feeder box for the busbar.



I have looked online but cant find the same busbar.

 

[Fozzy0207]

The last job i was on had some crappy legrand busbar system installed throughout the multi story carpark and main building. The connections were, L1-N-L2-E-L3 Where the SWA,s terminated in to the feeder box for the busbar.



I have looked online but cant find the same busbar.

This is the standard confirmation for busbar I have worked on. Mainly Eaton and E&I. The pitting on the bar will be as a result of a poor contact between the tap off fingers and the bar itself. Depending on the damage you will need to move the tap off position and potentially change out the length of bar as well. The fingers on the tap off are probably slack and will need replacing. A quality issue and may be covered under warranty. If you can’t move the tap off position I would change the fingers and depending on the damage clean up the bar and reinstate making sure to use good contact grease.

 

[Lucien Nunes]

Is this tinned aluminium busbar by any chance? (MPB is available with either copper or ali bars). If so, once damaged, the aluminium is exposed and will not make proper contact with the tap fingers even if it is cleaned up and tightened securely. Aluminium forms an insulating oxide layer instantly on contact with air, which requires abrasion under a layer of anti-corrosive paste to eliminate. A tap clamped on to bare ali could certainly make such poor contact that arcing would begin at low currents, or just be high resistance without arcing.

I don't have the MI's to know the official termination procedure but as above, I would start with a new set of fingers in a new position and make sure to proceed carefully regarding maintaining plating integrity.