If you decide to go ahead with a visit, it becomes a 'Conscious Decision To Appoint' (CDTA) fault. If our tests pass whilst on-site, and no audible noise can be heard ... then it becomes chargeable.
A 'hum' is usually associated with 'Earth faults' ..... a low resistance reading from one, or both, wire/s, to ground. If there is an internal cable linking the outside wire to your master socket, it could indeed be on that section as well as the chance of it being an external issue ?? You would be covered under 'Fair wear & tear' on your rental agreement though. In my experience, 'Earth faults' are
usually internal faults or E-side cable faults ....... the only other instance is a dropwire through trees if the premises is fed overhead ?.
However, tThe remote tests would generally pick these kind of faults up ?? So, in a nutshell, it's a bit of a gamble whether to proceed ?? Our 'Pair Quality Test' (PQT) does have wider quality gates than the remote test, so it may well find something
Good luck.