What a controller gives you, and when you do not need one.
Learning Track · Module 3: Controllers · Step 14 of 101
Showing content for Europe. Change the region at the top of the page.
Without a controller, you know a light is dark only when a resident reports it or a patrol drives past. A controller tells you in minutes.
What you get
- Faults without patrols. Each dark light, day burner, or tripped circuit raises an alarm.
- Flexible dimming. Change schedules for a street, an event, or a season from your desk.
- Measured energy. Know what each circuit or light uses.
- Proof for contracts. Uptime and repair times come from data, not from argument.
- Asset data. D4i drivers report model, burn hours, and faults automatically.
- A base for sensors. A Zhaga socket can hold a motion or air quality sensor later.
Check how you pay for energy
Europe: In some countries, the utility bills street lighting from an inventory, not a meter (an unmetered supply). In the UK, a CMS can act as an equivalent meter, so dimming reduces the bill. Check the rules with your supplier before you count dimming savings.
Middle East: Most networks are metered at the feeder pillar, so energy savings show on the bill. Where an authority pays a fixed rate, agree how savings are counted first.
South Asia: Most networks are metered at the feeder pillar, so savings show directly on the bill. Smart city tenders often make CCMS mandatory.
USA: Many US cities pay the utility a flat monthly rate for each light (an unmetered tariff). Dimming then saves nothing on the bill unless the utility offers a dimming or metered rate. Check the tariff first. Some cities buy their lights from the utility to get control of them.
What it costs
Hardware, installation, connectivity (SIM or network fees), and the platform. Add them over 10 to 15 years and compare with the savings. Use the cost of ownership tool.
When you may not need one
- Small networks where patrols are easy and cheap.
- Low-traffic roads where a driver profile (virtual midnight) gives most of the dimming saving.
- Where the maintenance process does not work yet. A controller finds faults, but somebody must fix them. Start with maintenance software.
Note
A good middle path: buy luminaires with a Zhaga Book 18 socket and a D4i driver now, even with no controller. Try the controller decision tool.
Sources
- Zhaga Book 18
- TALQ Specification
- Elexon guidance on unmetered supplies (Great Britain)
Changes: 30 October 2026: First publication: guides for Europe, the Middle East, South Asia, and the USA; failure library; tender clause library; comparisons; tools; downloads. See the changelog. Found a mistake? Report it.