Direct Burial Light Poles: Embedment Depth, Backfill and When to Use Them
Direct burial light poles explained: how they are installed, embedment depth rules, backfill and concrete, wood, steel, aluminium and fibreglass poles, pros and cons vs anchor base, and backyard uses.
Key points
- A direct burial pole has its lower part embedded in the ground instead of standing on anchor bolts.
- A common rule of thumb is embedment of about 10% of pole length plus 2 ft (0.6 m), but the engineer's design governs.
- Direct burial is quick and cheap for low and medium poles; anchor base poles are easier to replace and adjust.
- Backfill with compacted gravel or concrete, keep the pole plumb, and protect the ground line from corrosion.
Most commercial light poles stand on a concrete foundation with anchor bolts. A direct burial pole skips that: its lower section goes straight into a hole and is backfilled. The method is older than steel poles; wooden utility poles have always been set this way. This guide explains when direct burial makes sense and how to do it properly.
How direct burial works
The pole is made longer than its above-ground height. The extra length, the embedment, is set in a drilled or dug hole. The hole is backfilled with compacted soil, crushed stone or concrete, holding the pole upright against wind and fixture loads.
Direct burial poles come in:
- Wood: utility and rural poles, sports fields, rustic settings
- Steel: usually galvanised, with extra protection at the ground line
- Aluminium: often with a protective coating on the buried section
- Fibreglass (FRP): light, non-conductive, corrosion-proof; popular for residential and coastal sites
- Concrete: heavy, durable, used for roads in some regions
Embedment depth
A common rule of thumb is:
Embedment = 10% of total pole length + 2 ft (0.6 m)
| Above-ground height | Approximate embedment |
|---|---|
| 8 ft (2.4 m) | about 3 ft (0.9 m) |
| 12 ft (3.7 m) | about 3.5 ft (1.1 m) |
| 20 ft (6 m) | about 4–4.5 ft (1.2–1.4 m) |
| 30 ft (9 m) | about 5–5.5 ft (1.5–1.7 m) |
This is a starting point. Soft or wet soils, high wind speeds, heavy fixtures and slopes need deeper embedment, larger holes or concrete. Follow the pole maker’s design and local codes.
Backfill options
Native soil, compacted in layers. Cheapest; suitable only in firm soils for small poles.
Crushed stone, compacted. Drains well, easy to correct plumb, common for wood poles.
Concrete. Stiffest; good in poor soils and for taller poles. Allow a slight crown at the top so water runs away from the pole.
Compact backfill in 150–200 mm layers and keep checking plumb from two directions as you go.
Corrosion at the ground line
The ground line, where the pole meets soil or concrete, is where moisture, oxygen and salts concentrate. Steel poles corrode fastest here.
- Specify hot-dip galvanising plus a ground-line coating or sleeve
- Avoid letting grass trimmers and fertiliser damage the surface
- Keep a concrete collar sloped away from the pole
- Inspect the ground line during maintenance
Fibreglass and concrete poles avoid this issue.
Pros and cons
Pros:
- No anchor bolts or separate foundation; faster installation
- Lower cost for small and medium poles
- Works well for wood and fibreglass poles
- Simple in rural areas with augers or post-hole diggers
Cons:
- Harder to replace; the pole must be dug out
- Harder to correct plumb later
- Corrosion risk at the ground line for steel
- Breakaway designs for roadsides are more common with anchor bases
Anchor base poles, by contrast, sit on a reusable foundation and can be swapped after a vehicle strike. See square light poles for anchor base details.
Backyard and garden uses
For backyards, gardens and driveways, short direct burial poles are a practical way to raise lights above head height:
- Backyard pole lights: 8–12 ft poles with post-top or small area lights light a patio, play area or yard
- Driveway lights: short poles every 20–30 m along a long drive; see solar driveway lights
- String light poles: posts set to carry festoon lights over a patio
- Lamp posts: classic post-top lanterns; see driveway lamp post
Solar lights pair well with direct burial poles because no cable trench is needed at all. Our all-in-one solar street light is often mounted on 4–6 m poles for yards and private roads.
Wiring direct burial poles
Mains-powered direct burial poles have a cable entry slot below ground and a handhole above ground for connections. The cable runs in a duct to the pole and up inside it. Keep the handhole above flood and snow levels, and fit a sealed connection block. Mains work must follow local codes.
Installation steps
- Locate underground services before digging
- Auger or dig the hole to the required diameter and depth
- Place a layer of gravel at the bottom for drainage
- Insert the cable duct and set the pole
- Plumb the pole and brace it
- Backfill in layers, compacting each, or pour concrete
- Crown the top to shed water
- Remove bracing after concrete cures; fit fixtures and connect
Checking an existing direct burial pole
Older direct burial poles should be inspected for lean, cracks in the concrete collar and corrosion or rot at the ground line. For steel, dig back a little soil at the base and check the wall for pitting; for wood, test for soft rot just below ground. A pole that leans after storms may need deeper embedment or a concrete collar. Replacing a failing pole before it falls is far cheaper than repairing damage afterwards.
When to choose which
Choose direct burial for residential, garden, rural and park poles where cost and speed matter and replacement is rare. Choose anchor base for parking lots, roads and commercial sites where poles may be hit, need to be replaced quickly, or must meet breakaway rules. Our street light pole guide covers road poles in more depth.
Our supply
We supply LED and solar lights with poles for gardens, estates, parks and roads, in direct burial or anchor base versions. Send us the heights, quantities and site conditions, and we will propose poles and lights together.
Sources
Frequently asked questions
How deep should a direct burial light pole be?
A common rule of thumb is 10% of the total pole length plus 2 ft (about 0.6 m). For a 20 ft pole, about 4 ft. Soft soils, high winds and heavy fixtures need more, and local codes or the pole maker's design take precedence.
Should you set a direct burial pole in concrete?
Many are set in concrete for stiffness, especially in poor soils. Others use well-compacted crushed stone. Steel poles in concrete need protection where they leave the concrete, where corrosion concentrates.
What are direct burial poles used for?
Backyard, garden and driveway lights, residential street lights, parks and paths, sports fields with wood or fibreglass poles, and rural roads where quick installation matters.