Cabling is the least glamorous purchase in an office build-out and the one you live with the longest. Switches get replaced every five to seven years. Access points come and go. The cable in the walls stays for fifteen or twenty. We get called into plenty of offices where a "cheap" cabling job from years ago is quietly causing the problems someone is now blaming on the Wi-Fi, the switch, or the internet provider. Here is how to think about copper versus fiber, what actually matters in a cable run, and why cutting corners here is the most expensive discount available.
When copper is fine
For runs inside an office, standard Cat6 copper cable is the default and it is the right default. Cat6 comfortably carries 1 gigabit to 100 meters and 10 gigabit over shorter runs, and it delivers Power over Ethernet to access points, cameras, and phones over the same wire. Almost every drop to a desk, ceiling AP, or camera should be Cat6.
Cat6a is the step up: it holds 10 gigabit for the full 100 meters and handles PoE heat better in big bundles. It costs more and is stiffer and fatter, so it is harder to pull. We spec it for new construction where the walls are open anyway, for camera-heavy jobs, and for runs feeding wireless gear you expect to upgrade twice before the cable is touched again. Skip anything marketed as Cat7 or Cat8 for an office; those are answers to questions a small business is not asking.
One thing to insist on either way: solid copper conductors, not copper-clad aluminum. CCA cable is cheaper on the spool, performs worse, handles PoE poorly, and in many cases does not meet code. It shows up constantly in bargain jobs.
When fiber is worth it
Fiber earns its cost in three situations.
Distance. Copper Ethernet tops out at 100 meters, about 328 feet, and that includes the patch cables on both ends. A run from the front office to a warehouse, a detached building, or the far end of a long facility often blows past that. Fiber goes hundreds of meters to kilometers without breaking a sweat.
Electrical interference and isolation. Fiber is glass. It does not pick up noise from motors, fluorescent ballasts, or heavy machinery, and it does not conduct electricity. That last part matters between buildings: a copper run between two structures can carry lightning-induced surges and ground-potential differences from one building's electrical system into the other's network gear. Between buildings, fiber is not a luxury, it is the correct answer.
Uplinks. The links between switches, or between a switch stack and the server room, carry everyone's traffic at once. Running fiber for those backbone links, even inside one building, gives you an easy path to 10 gigabit and beyond without repulling anything later.
Fiber's downsides are real but smaller than they used to be: termination takes skill or pre-terminated assemblies, and it carries no power, so a far-end device still needs electricity or a PoE switch on its side.
Plenum, riser, and why the jacket matters
Cable jackets are rated for where they can legally and safely go. If a cable runs through air-handling space, which in many commercial buildings means the open area above a drop ceiling that HVAC uses for return air, it must be plenum-rated (CMP). Plenum jackets are built to resist burning and to give off less toxic smoke. Riser-rated (CMR) is for runs between floors, and general-purpose jacket is for everything less demanding.
Plenum cable costs noticeably more, which is exactly the corner a cheap bid cuts. The problem surfaces later: a fire marshal or building inspector flags it, an insurance claim gets complicated, or a landlord makes you rip it out. Ask your installer, in writing, what jacket rating is going where and why.
Testing and certifying: the part cheap jobs skip
There is a difference between a cable that lights up a link and a cable that performs to spec. A basic continuity tester proves the eight conductors are connected in the right order. A certification tester, the kind from Fluke and similar, actually measures the run against the Cat6 standard: crosstalk, return loss, length, the works, and produces a pass/fail report for every drop.
A run can pass continuity and still fail certification because of a sloppy termination, too-sharp bends, a staple crushed through the jacket, or cable pulled tight along a fluorescent fixture. Those runs mostly work, which is the worst outcome: intermittent errors, gigabit links that negotiate down to 100 megabit, PoE cameras that reboot randomly. Nobody suspects the wall.
Real installers hand over certification reports labeled per drop. Ask for them before the job starts, because asking after is too late.
Why cheap cabling is the most expensive option
The math is lopsided. Materials are a modest slice of a cabling job; labor and access are the bulk. Doing it right with solid-copper Cat6, proper jacket ratings, clean terminations, and certification might cost some percentage more than the lowest bid. Doing it twice costs double, plus the ceiling tiles, plus the disruption, plus every hour anyone spent troubleshooting "network problems" that were actually a bad punch-down in a wall.
We have replaced entire cable plants that were only a few years old. It is never fun to bill for, and it was always avoidable.
How to know it was done right
Walk-away criteria for a cabling job: every drop is labeled at both ends with matching identifiers. You have certification reports for every run, not a verbal "it all tested good." The jacket ratings match the spaces the cable passes through. Runs between buildings or past heavy equipment are fiber. Uplinks between switches have fiber or at least Cat6a with room to grow. And there is a simple floor-plan document showing where every drop lands.
Meet that bar and you will not think about your cabling again for fifteen years, which is exactly the point.
Stuck on this, or want it done for you? That's the job.
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