Cabling
Cable run length checker
TIA/EIA permits a 100 metre channel for copper. The part that catches people is what the 100 metres includes: the patch cords at both ends, not only the cable in the wall. This checks a proposed run against that, and against the roughly 90 metres it leaves for the permanent link.
Measure the whole channel
Does this run fit?
Enter the route as it will actually be pulled, not the straight-line distance on a floor plan.
Enter a run length and the result appears here. JavaScript is required for this panel; the rest of the page works without it.
What this tool checks, and what it cannot
- It checks length only. Length is necessary and not sufficient. A run inside the limit can still fail certification, which tests the installed link instead of its length.
- The 100 metre channel and the roughly 90 metre permanent-link limit are the TIA/EIA figures. The channel includes the patch cords at both ends.
- It states no attenuation, voltage-drop or temperature-derating figure. None of those is in our fact pack, so none is published.
- It states no PoE wattage, for the same reason: IEEE does not publish the per-class figures on its free pages.
- It assumes the length you enter is the route as it will be pulled. A straight line on a floor plan is consistently and substantially short.
- It never outputs "pass". That word belongs to a test performed on installed cable with a certifier.
The figure buyers miss
100 metres is the whole channel, patch cords included
This single detail is why runs that measured fine on a drawing fail after installation.
TIA/EIA permits a 100 metre channel for copper, roughly 328 feet. The number is widely known. What is far less widely understood is what it covers: the channel is the complete path from equipment to device, and it includes the patch cords at both ends, not only the cable in the wall.
That is why the practical permanent-link limit is about 90 metres. Two three-metre patch cords are six metres of your hundred before any cable enters a wall, and generous cords at both ends can take considerably more. Add slack coiled above a ceiling tile and the margin most people think they have is already spent.
Then there is the route. A camera position 70 metres away across a floor plan is frequently much further once the cable has gone up to a tray, along it, around an obstruction, and back down to the device. Runs near the limit are the commonest cause of a link failing certification later, and the failure arrives after the ceiling is closed.
Choosing the cable
Per run, against what that run has to carry
Cable selection is not a building-wide policy decided once. It is a decision per run, made against what that particular run has to do.
- Cat6a supports 10 Gigabit to the full 100 metre channel. Its construction also handles the heat generated by higher-power loads in a bundle, which is a real consideration: cable in a commercial building does not sit alone, it sits packed in a tray with a lot of other cable, and a bundle carrying power warms up.
- Cat6 remains appropriate for general workstation and voice work. Specifying the most capable cable everywhere is not diligence, it is spending pathway budget on runs that will never use it.
- Fibre is for backbone, for inter-building runs, and anywhere the path crosses separately grounded structures. That last case is a genuine electrical consideration, not a bandwidth one.
- Labelling is a standard too. ANSI/TIA-606 is the labelling and administration standard, and it is the difference between a system somebody can maintain in five years and one where every fault starts with tracing a cable.
Where a position genuinely sits beyond the limit, the answer is a change of design, not a change of cable: an intermediate location, or fibre. There is no cable that makes 120 metres of copper into a compliant channel, and anyone offering one is describing something that will not certify.
Why we will not say "pass"
Length is necessary. Certification is a test
A run inside 90 metres is a run that has cleared the first hurdle. It is not a run that will certify. Certification is a measurement taken on the installed link with a certifier, and it fails for reasons length never predicts: a marginal termination, a kinked or over-tensioned pull, a cord that is not what it claims to be, interference along the route, or water in an external junction.
This is the same reason we require test results per link instead of a general assurance when we specify a job, and it is a clause worth putting in your own tender — our RFP and specification template carries it.
The power side of the same cable has its own calculator, the PoE power budget checker, and its own write-up in the PoE power budget. The discipline behind a full cabling job — survey, design, install, certify, document — is under structured cabling, and the camera design that sits on top of it is under commercial camera installation.
Two boundaries, as on every page here. We work on commercial premises only and not on private residences. And we do not hold a C-10 or a C-16, so we do not work on fire alarm systems; that is coordinated with your own licensed fire alarm contractor.