ELECTRAGUARD.UK

If you’re renovating, extending, or installing underfloor heating, you may wonder whether electrical cables can be run directly through a concrete floor. The short answer is:

👉 Yes — electrical cables can be installed in a concrete floor, but only if they’re protected and installed correctly.

Here’s everything you need to know.

🔌 What the Regulations Say (BS 7671)
Electrical cables are allowed to run:
-In or under concrete floors
-Within screed
-Inside ducts or conduits
-Below insulation layers
But they must be protected against:
-Mechanical damage
-Chemical reactions
-Heat
-Moisture
-Movement caused during the pour
BS 7671 requires appropriate protection and routing — so you can’t simply lay a loose cable and pour concrete over it.

🧱 How Cables Should Be Installed in a Concrete Floor
✔️ 1. Use Conduit or Ducting
Cables should normally be run in:
-Plastic conduit (oval or round)
-Flexible conduit
-Rigid PVC ducting
-Metal conduit (for heavy-duty protection)
Why?
Conduit protects the cable and allows for replacement in future if a fault

✔️ 2. Use the Right Cable Type
Standard twin and earth (T&E) can be used if it is inside suitable conduit or ducting.
Armoured cable (SWA) may be used when:
-High mechanical protection is needed
-It’s running externally or underground to an outbuilding
SWA is not normally needed inside internal concrete floors.

✔️ 3. Keep Cables Away From Underfloor Heating
Electric or wet underfloor heating systems generate heat that can damage cables.
Clearances must be maintained, and in many cases, a thermal barrier is required.

✔️ 4. Avoid Running Cables Directly Under Load-Bearing Walls
Cables should not be crushed by:
-Structural elements
-Heavy steel reinforcement
-Fixings drilled later
Routing is important and must be planned before pouring.

✔️ 5. Maintain the Correct Depth
Cables should generally be:
-At least 50mm below the finished floor level, or
-Protected by conduit + RCD protection, or
-Installed to the manufacturer’s recommended depth

🚫 What You Should NOT Do
Never:
-Lay bare T&E cable directly into concrete
-Place cable where it can be punctured by fixings
-Run cables loose around rebar
-Cross hot heating pipes
-Pour concrete before the electrical installation is approved
These can all lead to:
-Electrical faults
-Overheating
-Fire risk
-Failed inspections
-Costly remedial work later

🏡 Typical Situations Where Cables Are Put in Floors
You’ll commonly see floor-installed cables in:
-Extensions
-Kitchen refits
-Garden room feeds
-Island sockets
-Underfloor heating controls
-Home offices in garages or outbuildings
It’s a normal practice — when done correctly.

✔️ So, Can You Put Cables in a Concrete Floor? (Simple Answer)
Yes — but only if they are properly protected using conduit or ducting and installed according to regulations.
Incorrect installation can make future repairs impossible and may cause overheating or damage.
If you're planning a project, always get the electrician involved before the concrete is poured.

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26/11/2025

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