Smart Home Cabling Guide: Cat6, Coax and HDMI Pre-wire for New Builds and Renovations

Quick Answer: A future-proof smart home pre-wire is structured cabling — Cat6 or Cat6A for data and PoE devices, RG6 dual-shield coax for satellite/aerial, optional HDMI 2.1 for video matrix systems, all terminated to a central hub (typically utility cupboard or under-stairs). Cat6A supports 10GbE up to 100m at £0.40–£0.85/m supply; Cat6 supports 1GbE at £0.20–£0.40/m. Run minimum 2× Cat6/6A to every habitable room and TV point during first fix — adding cables retrospectively is 10–20× more expensive.

Summary

Smart home pre-wire is the single most cost-effective electrical futureproofing decision in any new build or major renovation, and the most often skipped. A complete first-fix data and AV cable installation in a typical 4-bed house costs £450–£900 in materials and 8–14 hours labour at first fix — when the walls are open, joists exposed, and there's no plaster to cut. The same retrofitted post-completion costs £3,500–£8,000 in chasing, making good, redecoration, and labour. Skipping pre-wire saves £600 today and costs £4,000 in 5 years.

This guide covers the cable categories used in modern UK smart-home installs (Cat6, Cat6A, Cat7, RG6 coax, fibre optic, HDMI), the typical room-by-room cable specification, the structured cabling philosophy of central termination at a hub, and the relationship to BS 7671 wiring regs and Part P notification. It includes specific recommendations for new build vs renovation vs older property retrofit, the home-run vs daisy-chain decision, and the practical aspects of cable management at first fix.

The most important architectural decision: every cable terminates at a central hub, not chained between rooms. A typical 4-bed installation will have 25–40 cables converging on a 19" cabinet or wall-mounted patch panel in the utility cupboard. This makes future reconfiguration trivial (re-patching cables in a cupboard) versus impossible (rewiring a whole house). Old "telephone wired" houses with two-wire runs daisy-chained between rooms cannot support any modern data application — every retrofit becomes a full rewire.

Key Facts

Quick Reference Table — Room-by-Room Cabling

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Room Cat6/6A Coax HDMI Notes
Living room (TV wall) 2× Cat6A 1× RG6 2× HDMI 2.1 Plus 2× spare to TV position
Living room (sofa wall) 1× Cat6 — — Hidden cable for soundbar/sub
Kitchen 1× Cat6 — — Counter or undercounter outlet
Master bedroom (bed wall) 2× Cat6 — — TV point if planned
Master bedroom (workspace) 1× Cat6 — — Desk position
Other bedrooms 1× Cat6 — — Each room
Office / study 2× Cat6A — — Workstation futureproof
Hall (router/hub location) 4–8× Cat6 — — All home runs terminate here
Garage 1× Cat6 — — EV charger network sometimes wants Cat6
Loft 2× Cat6 — — WiFi AP, future use
External (cameras) 1× Cat6/6A per camera — — PoE cameras only
External (Doorbell) 1× Cat6 — — PoE smart doorbell

Detailed Guidance

Cable category selection

Choosing between Cat5e, Cat6, Cat6A, and Cat7 is a price-vs-futureproof decision:

Category Speed @ 100m Speed @ 55m Cost premium vs Cat5e Lifespan
Cat5e 1GbE 1GbE baseline 5–7 years
Cat6 1GbE 10GbE +33% 7–12 years
Cat6A 10GbE 10GbE +200% 12–20 years
Cat7 10GbE 10GbE+ +300% 15+ years (debatable)

For most domestic installs, Cat6 in the walls is the right answer: handles 1GbE everywhere, handles 10GbE on shorter runs (under 55m, which covers most domestic applications), and the cost premium over Cat5e is small. Cat6A is justified for office work areas, AV equipment locations, and any room expected to host a 10GbE workstation in the next decade.

Cat7 is generally overspec for residential. The connector ecosystem for Cat7 is GG45 or TERA, both rare and expensive — most "Cat7" cable in UK use is terminated to standard RJ45 connectors, which downgrades the cable to effectively Cat6A performance.

The structured cabling principle — home runs to a hub

Every cable runs from its outlet directly to a central termination point — typically a 19" wall-mount cabinet (£60–£200) or a wall-mounted patch panel in the utility cupboard or under-stairs. NOT daisy-chained from outlet to outlet.

The hub location should have:

Cable tray or conduit from hub location to ceiling void provides the route for all cables radiating out to rooms. Each cable is a "home run" terminated at the hub on a patch panel, then patch-cabled to the appropriate switch port.

This architecture means future reconfiguration is trivial — moving an internet-only port to a CCTV port is a 30-second patch lead change in the cabinet, not a wall chase across the house.

Coax (RG6) — when it's still needed

Despite the rise of streaming, satellite (Sky), terrestrial aerial, and any TV in a property still served by a satellite dish or roof aerial requires coax. Spec dual-shield RG6 (better noise immunity than single-shield RG59).

Run coax from the dish/aerial to the hub location, then from the hub to each TV point. F-type connectors at both ends. For Sky Q multi-room, both single and double shotgun cable (two paired RG6) is used — Sky Q hubs need two satellite feeds.

If the property has no satellite dish and TV is exclusively streamed (Netflix, Disney+, etc.), coax is optional but cheap and worth installing for futureproofing. RG6 is also occasionally used for security analogue cameras, though IP-over-Cat6 has displaced this.

HDMI runs — the difficult cable

HDMI 2.1 supporting 4K@120Hz over passive copper is limited to about 10m. For longer runs:

Best practice: install a 25mm conduit between AV equipment location and TV positions, then pull HDMI through the conduit. Future HDMI 2.2/2.3 cable changes don't require wall destruction.

Power over Ethernet (PoE) — the modern advantage

PoE devices that pre-wire benefits include:

A typical smart-home install includes 4–6 PoE devices; the PoE switch (8 or 16 port) sits in the central hub.

Specific room considerations

TV wall outlets: 2× Cat6A + 1× RG6 + 2× HDMI 2.1 in a wall plate behind the TV, plus a 13A socket. Run the cables in 25mm conduit from a junction box to the TV position. Allow extra cable length (1m+) coiled in the void for future TV mounting position changes.

Bedroom / study desk: 1× Cat6 to a desk-height outlet (above socket level, typically 750mm). PoE-capable for a desk phone if needed.

Loft: 2× Cat6 — one for a loft WiFi AP (PoE), one for future expansion (smart-home loft devices, security NVR if loft-mounted).

Kitchen: 1× Cat6 to an under-counter or worktop position. Often used for smart fridge, hub speaker, or intercom panel.

External: 1× Cat6 per planned camera position. Doorbell at front door. Outdoor WiFi AP. All PoE-powered. Use external-grade cable with UV-resistant jacket (LSZH or PE outdoor).

First fix vs second fix

First fix (during build):

Second fix (after plaster, before painting):

Never terminate cables at first fix — the cables need to remain in coils until plastering and painting are complete to avoid damage.

Cable management and BS 7671 considerations

Data cabling alongside mains power requires separation:

BS 7671:2018+A2:2022 Part 7 brings telecom cabling formally in scope of the wiring regs but data-only installation remains non-notifiable under Part P (Part P applies only to mains power circuits in dwellings).

For homeowners — what should I expect?

A complete smart-home pre-wire on a typical 4-bed new build costs £1,500–£3,500 supply and fit at first fix. Component breakdown:

Compared to the £3,500–£8,000 cost of retrofitting the same cable infrastructure post-completion, the case for first-fix pre-wire is overwhelming.

Frequently Asked Questions

Do I need Cat6A or is Cat6 enough?

For most domestic installations, Cat6 is enough. Cat6 supports 1GbE on every port (much faster than home internet speeds for the foreseeable future) and 10GbE on shorter runs (most domestic runs are under 55m). Cat6A is justified for:

For a normal lounge or bedroom outlet, Cat6 is fine.

Can I use existing telephone wiring for ethernet?

No. Telephone wiring is typically two-wire CW1308 cable, designed for analogue voice frequencies. Even modern Cat3 telephone cable lacks the twisted-pair geometry needed for ethernet. The bandwidth is inadequate (under 10MHz vs 250MHz for Cat6). Pull new Cat6 cables.

Do I need to notify Building Control for data cabling?

No. Part P notification applies to mains power circuit work. Data-only installations are not notifiable. However, if the data work is part of a wider electrical installation that is notifiable (consumer unit replacement, new circuits, kitchen/bathroom additions), it should be documented as part of that notification.

Should I run fibre to every room?

For most homes, no. Fibre is justified at the WAN entry point (incoming BT FTTP or ISP fibre service) and terminates in the hub. Within the house, Cat6/6A handles all current and near-future bandwidth needs. Consider fibre runs only for very long runs (>100m) or specialised AV applications.

Can I run Cat6 alongside power cable?

With separation. BS EN 50174-2 specifies 25mm minimum gap between Cat6 and unscreened mains power, increasing to 50mm for circuits over 10A. Crossing at 90° is preferred over parallel runs. Bundling data and power in the same conduit causes signal-integrity issues and is not best practice.

Regulations & Standards