Street Light Arm
- Arc-welded galvanized steel arm bracket that mounts to existing distribution pole face to hold an LED street light luminaire 1–3 meters out from the pole
- 6 types covering 1 m to 3 m projection lengths in single-arm and double-arm (180° opposing) configurations
- Standard 60 mm parallel tube end fits all common LED roadway luminaire mounting brackets per IEC 60598
- Hot-dip galvanized per ASTM A123 / BS5135 welded construction; pre-drilled pole-side flat plate accepts standard U-bolt or pole-band mount
Technical Specifications
| Catalog | Arm Type | Projection | Rise | Tube OD | Pole Mount | Wt (kg) |
|---|---|---|---|---|---|---|
| RAX-SLA-1S | Single arm | 1.0 m (3.3 ft) | 200 mm | 60 mm | U-bolt 150–220 mm pole | 6.5 |
| RAX-SLA-15S | Single arm | 1.5 m (4.9 ft) | 250 mm | 60 mm | U-bolt 150–220 mm pole | 8.5 |
| RAX-SLA-2S | Single arm | 2.0 m (6.6 ft) | 300 mm | 60 mm | U-bolt 180–260 mm pole | 11.0 |
| RAX-SLA-25S | Single arm | 2.5 m (8.2 ft) | 350 mm | 60 mm | Pole band 200–280 mm pole | 14.0 |
| RAX-SLA-3S | Single arm | 3.0 m (9.8 ft) | 400 mm | 60 mm | Pole band 220–320 mm pole | 17.5 |
| RAX-SLA-15D | Double arm @ 180° | 2 × 1.5 m | 250 mm | 60 mm each | U-bolt 180–260 mm pole | 16.0 |
Application & Installation
Where it is used
- Retrofit lighting on existing wood / concrete / steel distribution poles where no dedicated streetlight pole exists (the dominant retrofit use case for utility-cooperative LED upgrades)
- Rural roadway lighting where a single distribution pole carries both power conductors AND a mounted street light arm (saves the cost of a separate streetlight pole)
- Parking lot perimeter lighting on existing site poles — mount the arm + LED fixture without replacing the pole
- Median / boulevard configurations where one pole serves two opposing roadway directions (RAX-SLA-15D double-arm at 180°)
- Pedestrian path / sidewalk lighting at heights of 4–6 m where short 1 m arms suffice (RAX-SLA-1S)
Installation sequence (RAX-SLA-15S on wood distribution pole, U-bolt mount)
- De-energize the line if working within 1.5 m of any energized conductor; otherwise observe NESC working clearance per voltage class.
- Confirm arm mounting height: typically 6–8 m above grade for residential streets, 8–10 m for collector roads, 10–12 m for arterial. The arm should mount at least 1.5 m below the lowest energized conductor.
- Position the arm's flat plate against the pole face with the arm pointing toward the roadway centerline. Pass the 2 × M16 HDG U-bolts around the pole and through the plate's mounting holes.
- Install the U-bolt nuts + flat washers + lock washers on the back side; alternately torque to 80 N·m to settle the U-bolt around the pole circumference.
- Pull the luminaire feeder cable from the pole's lower handhole, up the inside of the pole, and out through the arm's rear cable entry hole; allow 30 cm service loop at the tube tip.
- Slip-fit the LED luminaire onto the 60 mm tube tip; tighten the luminaire's set-screws (typically 2 × M8 grub screws at 25 N·m). Connect the feeder + ground at the luminaire's wiring compartment.
Buyer’s Guide: Street Light Arm
1. What the Street Light Arm Actually Does — Pole-Mounted Lighting Retrofit
A Street Light Arm is a welded galvanized steel arm bracket that mounts to the face of an EXISTING distribution pole (wood, concrete, or steel) and projects horizontally outward to position an LED roadway luminaire over the lane it's lighting. Unlike a dedicated streetlight pole (which is purpose-built for lighting only), the street light arm shares an existing power-distribution pole — significantly cheaper than installing a separate pole, faster to deploy, and the dominant choice for utility-cooperative LED retrofit programs in rural and small-town distribution networks. The arm includes a pole-side flat plate for U-bolt attachment and a luminaire-side parallel tube sized 60 mm OD to fit any IEC 60598-compliant LED roadway fixture.
2. Projection Length Selection — By Roadway Geometry
Arm projection (the horizontal distance from pole face to luminaire) is set by the pole-to-curb offset and the roadway width to be illuminated. Rule of thumb: 1.0 m arm for narrow residential street (5–6 m pavement, pole at curb); 1.5 m for typical residential (7–9 m pavement with parking strip); 2.0 m for collector road (10–12 m pavement); 2.5 m for 2-lane arterial; 3.0 m for 4-lane arterial with median pole placement. Over-spec'ing increases wind load on the pole (the arm's leverage triples lateral moment per meter of projection); under-spec'ing leaves dark zones at lane edges that fail IES RP-8 photometric uniformity ratios.
3. Single Arm vs Double Arm (180°) for Median Installation
For roadways with a center median, two design approaches: Option A: install a single-arm street light on every pole along the median, with arms alternating left-right (RAX-SLA-15S or -2S). Option B: install a double-arm street light (RAX-SLA-15D) on every OTHER pole, with two opposing arms covering both lanes from one pole. Option B uses half the poles + half the arm assemblies but doubles the wind load + load moment on each used pole — require Class 4+ wood pole or pre-stressed concrete for stability. Cost analysis usually favors Option B for new infrastructure (saves trenching + pole erection labor) and Option A for retrofit (uses existing pole spacing).
4. Arc-Welded Steel Tube vs Aluminum Tapered (Mast Arm)
Two distinct pole-mounted arm products in the Raxsteel catalog: Street Light Arm (this page) uses arc-welded carbon steel tube + flat plate base, weighs ~10 kg per meter, HDG finish, costs ~$65 per arm for 1.5 m projection. Mast Arm (see related products) uses tapered aluminum 6063-T6 or steel sch 40, weighs ~5–9 kg per meter, mill-anodized or HDG, costs ~$120–200 per arm for similar projection. Use Street Light Arm when: budget-constrained retrofit, distribution-class wood pole, simple LED fixture, standard 60 mm tube mount accepted. Use Mast Arm when: dedicated streetlight pole, decorative aesthetic (tapered profile), coastal site (aluminum), or fixture requires 2-3/8″ ANSI tenon (C136.13 spec).
5. Pole Mount Hardware — U-Bolt vs Pole Band
The arm's flat-plate base attaches to the pole via one of two methods. U-bolt (RAX-SLA-1S / -15S / -2S): two heavy M16 HDG U-bolts wrap around the pole and through the plate's slotted holes — simple, fast, sufficient for poles up to 260 mm diameter and arms up to 2 m projection. Pole band (RAX-SLA-25S / -3S / -15D): a stainless steel banded strap with cinch buckle wraps the pole circumference and the plate bolts to the band fitting — required for larger pole diameters (220–320 mm) and heavier arms where U-bolt would deform under load. Pole band kits sold separately if you specify U-bolt mount but later find your pole exceeds 260 mm.
6. Galvanizing & the LED-Era Vibration Question
Standard Street Light Arms ship hot-dip galvanized per ASTM A123 at ~50 μm zinc coating. In normal C2–C3 atmospheric service expect 25–30 year service life. For coastal sites, specify duplex coating (HDG + epoxy paint, +$15/arm) for 40+ year service. The newer concern unique to the LED era: LED luminaires weigh 40% less than legacy HPS fixtures, so the arm's natural vibration frequency shifts upward into the 12–18 Hz range where wind-induced oscillation can excite resonance. For arms over 2 m projection in chronic-wind sites (mountain passes, coastal bluffs, open prairie), specify the 4 mm wall tube variant (suffix -4W) to shift resonance back below the wind excitation band — +$8/arm with 5-day add to lead time.
