Buzzing MK Sentry Consumer Unit

[vxxbcks]

Recently had consumer unit replaced with MK sentry job, split load.

Downstairs light circuit suddendly stopped working BUT the breaker hadn't tripped. Initially thought the breaker might have died but is working OK.

So inspected the connections in the consumer unit, no probs, and the various ceiling roses/junction boxes. One showed evidence of heat - clear plastic covers on the connection terminals discolored over the -ve's, and a general "soot" on the wires.

Removed, cleaned, inspected and reassembled. No apparent defects in the insulation on the cables, although there was a fair amount of unsheilded earth which I rectified. It was all a tight fit coming apart but went back much more neatly.

After reassembly the circuit now works fine. However, there is a slight buzzing coming from the consumer unit when lights are on, which increases with load, although the breaker doesn't trip. There are some LV downlightss with electronic dimmers and transformers on the circuit.

Any ideas on the buzzing?

Cheers
Jim.

 

[AdamW]

When you said "had replaced", I presume you got someone in to do the work? If I were you I would call them back to it as you are obviously dubious about the quality of their work since you resheathed the earth!

Soot on the insulation of a cable is not a good sign.

If I were you I would call the spark back and ask them to have a look at it. If the spark supplied the equipment, and the breaker or CU is faulty then it is up to them to replace it and take it up with their supplier.

If there was no humming before, and all they did was replace the CU then it is most likely that the fault lies at the CU end.