The guide
How deep should armoured cable be buried in a garden?
The UK wiring regulations do not set a fixed depth. They say a buried cable must be armoured or in a duct, marked with warning tape or covers, and deep enough to avoid foreseeable damage. The IET, which publishes the regulations, recommends a minimum of 500 mm. Your electrician sets the depth for your job.
Last checked 2 October 2026. We supply the sand, not the electrics: always use a qualified electrician.
What the regulations ask for
BS 7671, the UK wiring regulations, cover buried cables in Regulation 522.8.10. In plain words:
Armoured, or in a duct
A cable buried in the ground has to have an earthed armour or metal sheath, which is what steel wire armoured (SWA) cable has, or be run in a duct that protects it just as well.
Marked above
The route has to be marked with cable covers or a suitable warning tape laid above the cable, so anyone digging later finds it first.
Deep enough
It has to be buried deep enough that ordinary digging and ground movement will not damage it. The regulations themselves do not give a number.
How deep, then?
Because the regulations only say “deep enough”, the figure comes from guidance. The IET’s Guidance Note 1 recommends aminimum of 500 mm, to protect the cable from ground movement and frost heave.
Go deeper where the ground is likely to be dug, such as vegetable beds or anywhere a post might be driven in, or route the cable round those areas. Under a driveway or anywhere vehicles go, ask your electrician what they want. Their depth is the one that counts.
Why it needs an electrician
In England, running a new circuit, such as one to a garden office, workshop or car charger, is notifiable building work. It has to be done by an electrician registered with a competent person scheme, or notified to your local building control before it starts. Wales, Scotland and Northern Ireland have their own rules.
Many people dig the trench themselves to save money. Agree the route, depth and width with your electrician first, and leave the cable, connections and testing to them.
The layers in the trench
Sand under the cable, sand over it, warning tape or covers above, then the soil back to the surface. The sand keeps stones off the cable and makes it easy to find and dig out safely later.
- 1BackfillDug-out soil or imported fill, as the job specifies.
- 2Warning tape or tilesMarks the cable for whoever digs here next.
- 3BlindingCable sand packed over and around the cable, by hand.
- 4Cable or ductLaid on the bedding, never on stones or rubble.
- 5BeddingA compacted layer of cable sand across the full trench width.
Work out how much sand you need with the calculator. Most garden runs need a bulk bag or two. More for homeowners on the homeowners page.
Questions
How deep should armoured cable be buried in a garden?
The wiring regulations (BS 7671) do not give a fixed depth: they say deep enough to avoid foreseeable damage. The IET, which publishes them, recommends a minimum of 500 mm in its guidance. Dig deeper where the ground is likely to be dug, such as vegetable beds, and ask your electrician for the depth for your job.
Do I need armoured cable to a garden office?
A cable buried in the ground has to be armoured, or run in a duct that protects it as well as armour would. Steel wire armoured cable is the usual choice. Your electrician will choose the cable and size for the load.
Can I lay the cable to my garden office myself?
You can usually dig the trench, but in England a new circuit is notifiable building work, so it has to be done by an electrician registered with a competent person scheme or notified to building control. Wales, Scotland and Northern Ireland have their own rules. Ask your electrician before you start.
Do I need sand around armoured cable?
Bedding and covering the cable in clean, fine sand keeps stones off it and makes it easier to find and dig out safely later. A bulk bag or two is enough for most garden runs.
What goes above the cable?
Sand under and over the cable, then warning tape or cable covers above it, then the soil back to the surface. The trench bedding guide shows the layers.
Sources
- IET, Wiring Matters 101 (July 2024): Buried conduits and ducts. Explains BS 7671 Regulation 522.8.10 and the IET Guidance Note 1 recommendation.
- IET, Part P (England and Wales). Which electrical work has to be notified.
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Sand for your garden trench
A bulk bag or two, delivered to your door anywhere in the UK. One bag is fine.