Be careful not to confuse some “act of good faith” repair that may be made to a Lot Owner’s property by the Owners Corporation subsequent to some “event” occurring on its Common Property, with what may be covered by its Strata Insurance.
The only “lot property” that Strata Insurance covers are those parts of a Lot that are considered to form part of the Common Property, and the cover for “lot owners’ fixtures” relates only to items that have been fixed in some permanent way to a part of the Common Property within a Lot by the Owner.
Even if the security system was installed as part of the building’s construction, if it’s for Ross‘s Lot only and it doesn’t form part of some centralised system that is perhaps integrated with the intercom, then I agree with Marvin (thread#3); it’s his responsibility.
As Ross‘s intercom wasn’t fitted by him it’s not a “lot owners’ fixture”, but the responsibility for the cabling from the handset in his Lot back to the main access panel has been correctly accepted by the Strata Manager as an Owners Corporation responsibility, as should the electrical supply cabling from the sub-board in Ross’s Lot to the “common meter box”.
Marvin‘s advice about the electricity supply cabling is correct – try to have your Strata Manager treat the maintenance of that in the same way as they have agreed to for the intercom cabling; perhaps ask your neighbours if they’re experiencing similar problems.
There are a few nuances around the electrical wiring in the Lot and a few other items, but a reference to them here would only serve to confuse matters (further); so I won’t.