If you walk into any high-street electronics shop and ask for ethernet cable, you'll be shown three options, each marketed harder than the last, and you'll leave with whichever one the bloke behind the counter pointed at. Here's what's actually different between them, and what to choose for a London home.
The short version
For almost every London house, flat or home office: Cat6 is the right answer. Not because it does anything Cat5e can't at gigabit, but because the spec difference is trivial in the bigger picture and you get headroom for the next router upgrade you'll inevitably make.
I haven't installed Cat5e in a new build in three years. I haven't installed Cat6a in a residential property ever — that's commercial-grade kit for server rooms and offices with 10-gigabit backbones, which isn't your kitchen.
The comparison
| Spec | Cat5e | Cat6 | Cat6a |
|---|---|---|---|
| Max speed (any distance) | 1 Gbps | 1 Gbps | 10 Gbps |
| Max speed at 100m | 1 Gbps | 1 Gbps | 10 Gbps |
| 10 Gbps possible at | — | up to 55m | up to 100m |
| Bandwidth | 100 MHz | 250 MHz | 500 MHz |
| Outer diameter | ~5.5mm | ~6.5mm | ~7.5mm |
| Shielding (typical residential) | U/UTP | U/UTP | F/UTP or S/FTP |
The thing nobody tells you is that the cable itself is the smallest part of any install. A typical run takes 60–90 minutes of labour (chasing cable through floors and walls, terminating both ends, testing), and the wall plate, jack and patch lead are also part of the parts list. The spec difference between Cat5e and Cat6 is invisible against the rest of the install — and you keep the future-proofing.
When Cat5e is fine
- Existing Cat5e already installed and working. Don't rip it out. It handles 1 Gbps, which is faster than your broadband and faster than most domestic equipment can sustain. Use it. Spend the time on something else.
- Adding one or two short runs in a property that already has Cat5e. Mixing cable types in the same install is generally fine for residential — you'll be limited to the slowest cable in any given path, but Cat5e gigabit is the practical ceiling anyway for most home use.
- You're a tenant with a six-month lease and you want a wired connection to one room. Cat5e patch lead, cable clip it round the skirting, take it with you when you go.
When Cat6 is what to install
- New install, any new build or renovation. Default to Cat6. The spec difference over Cat5e is invisible against the labour, and you keep the headroom.
- PoE+ powered cameras, doorbells, access points. Cat6's better noise margin and slightly thicker conductors handle PoE+ heating better over long runs. Critical for outdoor cameras with longer cable runs.
- Anywhere you'll regret installing Cat5e in five years. Server room in the under-stairs cupboard, dedicated home office for a video editor, anything that might one day need 2.5 GbE or 10 GbE.
James in Hackney is a video editor. Warehouse conversion, suspended ceiling above everything, single existing Cat5e run from a wall plate behind the TV. He was losing Dropbox syncs over WiFi daily and uploading 4K footage to a NAS in the cupboard.
I installed four Cat6 runs from a small patch panel next to the router: one to his desk, one to the NAS, one to the TV, one spare. All terminated to Cat6-rated keystone jacks, Fluke-tested for length and crosstalk before I left. His desk connection now runs 2.5 GbE to a switch he bought afterwards. Cat5e would have capped him at 1 Gbps. With Cat6 he's got room to upgrade the switch and the NAS without re-cabling.
Choosing Cat6 over Cat5e in his case meant a marginal spec difference across the whole install. The benefit in resale and future-proofing is the bit that matters.
When Cat6a is overkill (almost always, for homes)
Cat6a is the spec for 10-gigabit ethernet over the full 100-metre run. Three things are true about that:
- You don't have 100-metre runs in a domestic property. Most London flats are under 25 metres end-to-end.
- Cat6 already supports 10 Gbps over runs up to about 55 metres. Most London houses fit inside that.
- You don't have 10-gigabit equipment. Your laptop has a 1 Gbps port. Your TV has a 1 Gbps port. Your NAS, if you've got one, is probably 1 Gbps. Even the latest gaming PCs ship with 2.5 GbE, which Cat6 handles trivially.
Cat6a is also harder to install. The cable is fatter, the bend radius is bigger, the terminations are fiddlier, the shielding has to be earthed properly. Anyone who installs it in a residential property either has a specific reason (rare) or is upselling.
The exception: if you're wiring a server room in your basement and you genuinely need a 10 GbE backbone to multiple workstations, sure, Cat6a or fibre. But that's a specialist install and you'll know if it applies to you.
What I install
For 95% of London residential jobs: unshielded Cat6 (U/UTP), terminated on Cat6 keystone jacks at the wall and a 24-port patch panel at the router end. Pure-copper conductors (not copper-clad aluminium — a common shortcut on cheap cable that ruins PoE performance). The cable colour matches the keystone jack so future engineers can trace it.
I'll spec shielded Cat6 (S/FTP) if the run is going alongside mains cabling for any distance, or if the customer is in a flat with significant electrical noise nearby. But that's maybe one job in fifteen.
The PoE camera question
Tom in Fulham wanted a single ethernet point at his front door for a PoE camera above the porch. PoE means Power-over-Ethernet — the camera takes both data and power down the same cable, no separate plug needed. Modern outdoor cameras use PoE+ (up to 30W) or PoE++ (up to 60W) and they get hot. Heat moves down the cable.
Cat6 handles PoE+ comfortably. Cat5e can do it on shorter runs but starts losing voltage on anything over about 25 metres, and the heating on the cable jacket is noticeable. For an outdoor camera with a 15-metre run through a wall to the porch, Cat6 is the only sensible choice.
Common installation mistakes
Three things go wrong with ethernet cabling regardless of which Cat type:
Wrong termination pinout. T568A and T568B both work, but you have to use the same one at both ends. Mixing them creates a "crossover cable" by accident, which works for some equipment and not others, intermittently. I always use T568B as the default — same as Openreach.
Untwisting too far during termination. The twists in the cable pairs are what give it its noise rejection. If you untwist the pairs more than ~13mm at the termination, you lose the crosstalk protection and your Gigabit drops to 100 megabit silently. Quality terminations are what separate a cable that does what it says on the tin from one that throttles every device on the network.
Not testing. Every cable I install gets tested with a Fluke MicroScanner — length, wiremap, signal-to-noise. If anyone runs you Cat6 and doesn't hand you (or email you) a test certificate, you don't actually know what you've got.
Common questions
Is Cat6 worth installing over Cat5e?
For a new install, yes — the spec difference is invisible against the labour and Cat6 future-proofs you for 2.5 GbE and 10 GbE equipment. For an existing working Cat5e install, no — leave it and put the effort somewhere else.
What's the difference between Cat6 and Cat6a?
Cat6 supports 10 Gbps up to about 55 metres. Cat6a supports 10 Gbps over the full 100 metres and has heavier shielding for noise rejection. For domestic runs (almost always under 30 metres), Cat6 hits the same gigabit ceiling with easier termination.
Can I run Cat6 alongside mains power cables?
Not in parallel for long runs. Crossing perpendicular is fine. UK best practice is at least 50mm separation between mains and data cables when they run parallel. Shielded Cat6 (S/FTP) is more tolerant — worth the upgrade if your route has no choice but to follow the ring main.
Do I need shielded or unshielded cable?
Unshielded (U/UTP) is the right answer for residential. Shielded (S/FTP, F/UTP) makes sense in commercial fit-outs, flats with industrial equipment nearby, or runs that must follow mains cabling. Shielded cable needs proper earthing at the panel end — not all installers do that correctly.
Need data cabling installed?
Tell me what you want connected and where. Ring me and we'll talk through the cable spec, the route, and what gets tested before I leave.