Pole shaft (pole)Hollow tube of steel or aluminum with the wiring inside.
Luminaire (light fixture, head)The complete lighting unit: light source, optics, housing and power parts.
Mast armHolds the luminaire out from the pole and over the road.
LanternThe glazed head of a post-top lamp that shelters the light.
Base (pedestal, plinth)Wide cast foot of the post, often shaped with moldings.
FoundationConcrete or steel footing in the ground that holds the pole.
Fluted column (post)Flutes are the shallow grooves that run up the post.
Photocell (photoelectric control)Senses daylight, switching the light on at dusk and off at dawn.
Roadway street light 9
Anchor boltsCast into the foundation; nuts on top clamp the base plate.
LensGlass is advised; plastic lenses tend to discolor over time.
HousingWeathertight aluminum shell that holds everything else in the head.
Base plateFlat plate under the shaft with holes for the anchor bolts.
Handhole and coverSmall covered opening near the base for reaching the wiring.
Light source (LEDs or a lamp)Turns electrical energy into light: LEDs today, a lamp in older heads.
ConduitBuried tube that brings the supply wires up through the foundation.
SlipfitterBolted clamp at the back of the head that grips the arm.
House-side shieldOptional plate that blocks light spilling back toward houses.
Post-top street lamp 3
FinialAn ornament that marks the very top of the lantern.
Glass panesLet the light out and keep wind and rain off.
Ladder bar (ladder rest)A crossbar for a ladder; lamplighters carried one to tend the lamp.
How this list was compiled: Part names and the fact lines were written for this site and checked on 2026-09-20 against these sources, and the part names again on 2026-09-30; nothing was copied. A name is ringed only when two of them use it. (1) US Federal Highway Administration, FHWA Lighting Handbook, August 2012, read in the Internet Archive copy https://web.archive.org/web/20221228020107/https://safety.fhwa.dot.gov/roadway_dept/night_visib/lighting_handbook/pdf/fhwa_handbook2012.pdf because the agency's own host refuses automated fetches: luminaire as a complete lighting unit, glass lenses and why plastic ones discolor, the aluminum housing with tool-less entry, breakaway devices between foundation and pole, post-top lighting. (2) Minnesota Department of Transportation, Roadway Lighting Design Manual, May 2010, https://edocs-public.dot.state.mn.us/edocs_public/DMResultSet/download?docId=26348029 (linked from https://www.dot.state.mn.us/trafficeng/lighting/index.html): glossary entries for lamp, mast arm, davit and truss mast arms, transformer base, shoe base, slip base and post top lighting unit; pole shaft, pole base plate, anchor bolts in a bolt cluster, light bases and foundations of concrete or steel, conduit, the slipfitter and the luminaire housing, shields, and the rule that a luminaire has a photocell only where the service point has no photoelectric control. (3) Washington State Department of Transportation, Standard Specifications M 41-10, 2027 edition, Division 9, sections 9-29.6, 9-29.7, 9-29.10 and 9-29.11, https://wsdot.wa.gov/publications/manuals/fulltext/M41-10/Division9.pdf: shafts, base plates, handhole covers, anchor bolts and anchor rods, luminaire arms, aluminum weathertight housings, the four bolt slip-fitter mount on a tenon, house side shields, photocell sockets with shorting caps, twist-lock photoelectric controls, LED drivers behind an access door, fused connector kits at light standard bases. (4) A pole maker's product pages, https://lightpolesplus.com/products/10-tall-x-3-0-od-x-11ga-thick-round-straight-steel-anchor-base-light-pole and https://lightpolesplus.com/products/10ft-4in-od-abingdon-fluted-decorative-light-pole: pole shaft, top cap and tenon top, hand hole with cover and grounding provision, base cover, anchor bolts with an L bend, hex nuts and washers, fluted shaft, cast decorative base, handhole or base door for anchor bolt and wire access. (5) A luminaire maker's product page, https://leotek.com/product/greencobra-led-streetlight-gcm/: house-side light trespass shields, the mast arm entry, the photocell receptacle and the terminal block. A fixture page of the pole maker, https://lightpolesplus.com/products/40w-willstudio-mvx-architectural-coach-led-light-fixture , names the LED module, driver and heat sink. The plan asked for two makers' installation guides; the guides themselves sit behind download tokens, so the makers' public product pages were read instead. (6) Wikipedia, https://en.wikipedia.org/wiki/Street_light (light-sensitive photocells that switch the lamp automatically, mounting arm, lanterns with glass windows), https://en.wikipedia.org/wiki/Lantern (street lights enclosed in glass panes; an enclosure that keeps wind and rain off the light source), https://en.wikipedia.org/wiki/Finial, https://en.wikipedia.org/wiki/Fluting_(architecture) and https://en.wikipedia.org/wiki/Lamplighter (lamplighters carried a ladder and renewed candles, oil or gas mantles). (7) Descriptions of listed cast iron lamp posts, which cite the National Heritage List for England, in Wikipedia's lists https://en.wikipedia.org/wiki/Listed_buildings_in_Chesterfield,_Derbyshire , https://en.wikipedia.org/wiki/Listed_buildings_in_Middleham and https://en.wikipedia.org/wiki/Listed_buildings_in_Nottingham_(Mapperley_ward) (ladder rest), https://en.wikipedia.org/wiki/Listed_buildings_in_Burnley and https://en.wikipedia.org/wiki/Listed_buildings_in_Harrogate_(Bilton_Ward) (ladder bars), https://en.wikipedia.org/wiki/Listed_buildings_in_Rochdale (fluted shaft, capital, hexagonal lantern with a finial), https://en.wikipedia.org/wiki/Listed_buildings_in_Churchtown,_Merseyside (pedestal, shaft, lantern with a finial) and https://en.wikipedia.org/wiki/Listed_buildings_in_Wigton (fluted column on a plinth, ladder brackets, lantern). (8) Added on 2026-09-30 as a second, independent source for the ladder bar: Wikipedia, https://en.wikipedia.org/wiki/Honeyfield_Drinking_Fountain , a New Zealand monument described from Heritage New Zealand's list and a 1907 newspaper (a tapering lamp post of cast iron with an ornate ladder bar under a hexagonal lantern). Ladder rest is printed only in the English listings of (7), so the label now gives ladder bar first. Licence: own work
The drawing: Drawn for this site on 2026-09-30 from plain geometry. Own original schematic drawing of composite teaching lamps; nothing traced or copied, and no maker's product is shown. Licence: own work
How it works
The parts of a street lamp fall into two sets: the head that makes and aims the light, and the pole, base and footing that hold it up. Four drawings show a roadway light, its head, its foot and an old post-top lamp.
Read the full guide
Parts of a street light, from the ground up
A foundation sits in the ground with anchor bolts cast into it and a conduit bringing the supply wires up through the middle. Nuts on the bolts clamp the base plate, and the pole shaft rises from it, with a handhole low down for reaching the wiring. Near the top the mast arm reaches over the road, and the slipfitter at the back of the luminaire grips the end of the arm.
What the old post-top lamp has instead
It has no arm. The lantern sits straight on a fluted column above a wide cast base, with glass panes on its sides and a finial on top. The crossbar under the lantern is the ladder bar.
Pick the group Post-top street lamp for its 6 parts alone: lantern, finial, glass panes, ladder bar, fluted column and base.
Start here: 8 main parts covers what you can name from across the street, from the pole shaft to the lantern.
Questions and answers
What is the knob on top of a street light?
It is the photocell, part 11. It senses daylight and switches the light on at dusk and off at dawn. Not every head has one: where a control cabinet switches a whole row of lights, the socket carries a plain shorting cap instead.
What is the difference between a luminaire and a lamp?
The luminaire is the complete lighting unit: housing, lens, light source and the parts that power it. The lamp is only the light source inside. In newer heads an LED array takes the lamp's place.
What is the bar across an old street lamp for?
It is the ladder bar, also called a ladder rest, part 17. It gave a ladder something to lean on just below the lantern. Lamplighters carried a ladder on their rounds to renew the candles, oil or gas mantles.
What is the small door at the bottom of a light pole?
It is the handhole, part 15. Behind its cover are the wiring connections and, on many poles, a fuse for the luminaire. A decorative post often puts the same opening behind a door in its base.