A street lamp has a job no other outdoor fitting has: it lights a surface that vehicles cross at speed, from a height where the fitting itself is out of reach. That single requirement drives everything below — the column, the optic, the ingress rating and the surge protection.
On an adopted public road the specification is fixed by the highway authority and the lighting class comes from EN 13201. On a private estate road, a farm track or a long approach drive you choose it yourself, and most people over-specify. A 6 m column with a 40 W LED head does more for a private road than a 10 m column borrowed from a trunk-road catalogue, and it costs far less to maintain.
| Use | Column height | Typical spacing |
|---|---|---|
| Private drive, single-track approach | 3–4 m | 12–16 m |
| Estate road, car park aisle | 4–6 m | 18–25 m |
| Two-lane residential street | 6–8 m | 25–35 m |
Spacing of roughly four times the mounting height gives an even carriageway with no dark pockets between poles. A post-top lantern throws light symmetrically and suits a straight run; a bracket with outreach pushes the light over the carriageway and is the better choice when the columns stand behind a verge or a kerb line.
Street heads sit in the weather with no shelter at all, so IP66 is the working minimum — dust-tight and proof against powerful water jets, which is what a lorry throws up in the wet. IK09 or IK10 protects the diffuser from stones. The failure that catches people out, though, is electrical: overhead and roadside supplies carry switching and lightning transients, and an LED driver without surge protection dies quietly in the first bad storm. Look for a head rated to 10 kV, or fit external protection at the feeder pillar.
There is no low-voltage version of this category. A street lamp is a fixed 230 V installation: armoured or ducted cable buried below the frost and plough line, a cut-out or feeder pillar with proper isolation, earthing or Class II double insulation throughout, and a residual current device on the circuit. This is qualified-electrician work everywhere in Europe, and on anything that touches a public highway it is notifiable work as well.
The head rarely fails first — the base does. De-icing salt sits in the splash zone for months, and a column bolted flat onto a concrete pad holds that brine against its own weld. Galvanised steel with a powder-coat topcoat, a raised base flange and a drainage path out of the door aperture buy years. Within a few kilometres of the coast, specify A4 stainless fixings rather than A2; the cheaper grade will streak rust down a new column in a single winter.
Obtrusive light is the most common complaint about new street lighting, and it is almost always an optics problem rather than a brightness problem. A flat-glass, full cut-off head puts nothing above the horizontal; a decorative lantern with a domed bowl scatters light into first-floor windows and into the sky. Where columns stand close to houses, choose a head with a rear shield or an asymmetric optic. Warm white around 3000 K reads as calmer at night, disturbs sleep less than 4000 K, and is now the default in most residential retrofits.
Far less than a public road. Continuity matters more than level — an unbroken line of modest light beats a few very bright poles with darkness between them.
A photocell handles dusk and dawn without seasonal adjustment. Pair it with a driver that dims after midnight if the run is long; that combination cuts running cost without leaving the road unlit.
On a short private drive in a sunny position, yes. On a road that must be lit reliably through a northern winter, no — panel output at that latitude in December is a fraction of the summer figure.
For lower mounting heights and softer applications, see the wider outdoor lighting range.
