4-Aspect Traffic Signal Head Wiring: Red Yellow Green and Arrow Sections
Introduction
A 4-aspect signal head adds a fourth indication (usually a green or yellow arrow) to the standard red/yellow/green ball. Used for protected left turns and split phases, 4-aspect heads need six switched conductors plus common. This guide covers the wiring standard.
The Six Switched Conductors
A 4-aspect head with red ball, yellow ball, green ball and green arrow needs:
- Red ball (RB)
- Yellow ball (YB)
- Green ball (GB)
- Red arrow (RA) - if it's a 5-aspect arrow head
- Yellow arrow (YA) - if it's a 5-aspect arrow head
- Green arrow (GA)
Plus one common conductor (COM) shared by all six. Total: 7 conductors, sized to the run length.
Wire Colours by Region
| Conductor | North America | Europe (IEC) | China (GB) |
|---|---|---|---|
| Red ball | Red | Brown | Red |
| Yellow ball | Yellow | Orange | Yellow |
| Green ball | Green | Green/Yellow striped | Green |
| Common | White or Grey | Blue | Blue |
| Arrow red | Red (separate) | Brown | Red |
| Arrow yellow | Yellow (separate) | Orange | Yellow |
| Arrow green | Green (separate) | Green | Green |
Always confirm the project's colour code before pulling wire.
Cable Gauge and Length
Use 14 AWG for runs up to 100 m, 12 AWG for 100-200 m, and 10 AWG for longer runs. Size for voltage drop (max 3% at the signal head), not just ampacity. For long runs, drop to a lower gauge to reduce voltage drop.
Terminal Layout in the Head
The terminal block in a 4-aspect head has one terminal per switched conductor plus a common bus. GAOQIAO heads use numbered terminals that match the wiring diagram. Wire entry is through a waterproof cable gland on the bottom of the housing. Leave 1-2 m of service loop inside the head for future maintenance.
Featured Products
GAOQIAO supplies 4-aspect and 5-aspect arrow heads with documented terminal layouts. See the wiring diagram guide.
Conclusion
A 4-aspect signal head needs six switched conductors plus common, sized for the run length. GAOQIAO heads ship with documented terminal layouts. Send us your run length and project colour code for a wire schedule.
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Frequently Asked Questions
What gauge wire for a 200 m run?
12 AWG minimum, 10 AWG preferred. Verify with a voltage drop calculation.
Can I use a single multi-conductor cable?
Yes. GAOQIAO supplies 7-conductor traffic signal cable with colour-coded insulation. Use a single cable from the cabinet to each head, not multiple single conductors.
How do I label the conductors?
Use heat-shrink markers at both ends matching the head's terminal numbers. GAOQIAO supplies labelled cable on request.
Relevant GAOQIAO products
These public GAOQIAO catalogue pages are related to the guide. Open them for the representative description, then confirm the latest drawing and configuration before ordering.
- Traffic signal controllersWired and solar controllers with 6, 22, 44 and 56 output options.
- LED traffic signal heads200mm, 300mm and 400mm signal heads with MUTCD, EN12368, GB14886 compliance.
- Signal polesVertical, signal arm and double-arm poles for any intersection geometry.
- Spare parts and accessoriesSpare LED modules, lenses, visors, surge arrestors and anchor bolts.