Structured cabling: what to require from your contractor

Require a design before anyone pulls cable

Structured cabling is defined by having a design: where distribution points sit, how each floor or block is served, how many outlets a work area gets, and how the system is expected to grow. Without that, you are buying cable runs, not a cabling system.

Ask for the design as a document you can read. It should be understandable by a facilities manager, not only by the person who drew it, because that is the person who will use it in three years.

Require an outlet schedule with spare capacity stated

A quotation for "data cabling to the office floor" cannot be compared with anything. A schedule listing every outlet position, and how many outlets each position gets, can be.

Ask explicitly what spare capacity is included — spare outlets, spare containment space and spare patch positions. Spare capacity is the difference between absorbing a departmental move in an afternoon and treating it as a new project.

Require containment sized for later, not just for today

Trunking, tray and riser pathways are the constraint everyone forgets. Filling containment on day one guarantees that the next addition means new containment, usually through a finished ceiling.

Containment should also be installed before cable is pulled. If a contractor's sequence has cable going in first and containment appearing afterwards, expect a compromised result.

Require test results for every link

This is the single most useful thing to insist on. Ask for per-link test results — one recorded result per outlet — rather than an assurance that everything was tested.

Testing serves you twice: it catches bad terminations before they become intermittent faults months later, and it establishes the condition of the installation at handover, which matters if a fault is disputed.

If a contractor resists producing test results, that tells you something useful about the installation.

Require labelling and as-built documentation as part of handover

An installation without labelling is unfinished, however neat the cable dressing looks. Both ends of every link should carry a consistent label, and the labelling scheme should be recorded.

As-built documentation — what actually got installed, as opposed to what was designed — is what allows any future contractor to work on the system without rediscovering it. Make it a handover condition, not a favour asked afterwards.

• Consistent labels at outlet, patch panel and rack
• A record of which outlet lands on which patch position
• Per-link test results
• Updated drawings or schedules reflecting what was installed

Ask about standards in practical terms

Cabling categories, separation from power runs and length limits exist for good practical reasons, and any competent contractor will discuss them plainly. Ask what cable category is being installed and why, what the longest run is, and how data is being kept away from power and heat.

The useful test is not whether the answer cites a document. It is whether the contractor can explain, in terms you understand, what the choice means for the equipment you will connect over the next several years.

Agree coordination and disruption before the start date

Cabling interacts with ceilings, partitions, power and air conditioning, and in an occupied building it interacts with your staff. Agree working hours, routes, dust control and the sequence with other trades in advance.

This is also where phasing gets decided honestly. Phased cabling works well when the whole system is designed first and each phase fits that design — and badly when each phase is designed on arrival.