Structured cabling has one feature that sets it apart from the rest of IT infrastructure: it gets replaced once every 15–20 years, so almost nobody in the company remembers what the previous replacement looked like. And then it turns out that an office of 300 people has to be re-patched in a way that leaves everything working on Monday morning.

When an upgrade makes sense

Three signals show up most often. First, the network can no longer keep up — a cabling category from the days when 100 Mbps satisfied everyone now throttles traffic to the server room and to Wi-Fi access points. Second, the racks are chaos: years of ad-hoc additions without documentation mean tracing a single outlet takes an hour. Third, an office redesign after which the old cable routes simply no longer match the new desk layout.

There is also a harder signal: new systems — IP-based access control, cameras, building automation, telephony — need PoE power and bandwidth the old installation cannot deliver.

Phased delivery instead of a big bang

The biggest mistake is planning the replacement as a single sweep. In a live office, a zone-based approach works: the building is divided into areas, each area gets its own delivery window, and the old and new installations run in parallel for a while. Noisy, dusty work — core drilling, cable trays in corridors — is scheduled for nights and weekends; re-patching workstations happens in the evenings, zone by zone, a few dozen outlets at a time.

Sequence is critical: new routes and racks first, then new cabling installed and tested, and only at the end the users are switched over. That way the cutover takes minutes rather than days — and if anything goes wrong, you can always fall back to the old installation.

Testing and documentation: the difference between an installation and a tangle

Every cable link should be measured with a certified tester, with a test report for every outlet. This is not bureaucracy: the report settles warranty disputes later and saves hours of troubleshooting. Add as-built documentation — floor plans with outlets marked, rack labels matching workstation labels, consistent numbering. An installation without documentation loses half its value on the day it is handed over.

What to ask your contractor

Whether they provide the cabling manufacturer's system warranty (25 years is standard with serious vendors), how they plan phasing and out-of-hours work, whether certification testing and as-built documentation are included in the quote, and who on their side coordinates with other trades — because in an office building a cabling replacement always touches suspended ceilings, power and fire protection.

A well-run upgrade is almost invisible to users. That is the right measure of its success.