Zhaga and D4i: the standard for smart street lighting

Why municipalities ask for Zhaga-D4i

Smart street lighting was a closed system for a long time: node, driver and management software from a single supplier. Anyone wanting to switch after a few years often had to open every luminaire. For some years now there has been an open alternative: the Zhaga socket on the luminaire combined with a D4i-certified driver. More and more municipalities include that combination in their specifications, because every certified node fits every certified luminaire.

For you as an installer this means a luminaire you fit today can take a node or sensor later without tools. No opening up, no extra wiring, no new driver.

The Zhaga socket on the luminaire

Zhaga is the consortium that standardises interfaces for LED luminaires. For outdoor lighting, Book 18 applies: a four-pin socket on the top, the bottom or both. Two pins carry 24 V DC auxiliary power from the driver, the other two form the DALI bus. A node or sensor twists onto the socket with a bayonet fitting and is powered and connected in a single action.

The socket is compact, weatherproof and smaller than the older 7-pin NEMA socket. Without a node, a blanking cap seals the socket so the luminaire keeps its IP rating.

D4i: requirements for the driver and the data

D4i is a certification by the DALI Alliance on top of DALI-2. A D4i driver powers the node, keeps its own records and passes them on over the bus:

• Energy metering: power drawn and consumption per luminaire.
• Diagnostics: burning hours, driver temperature and fault reports.
• Luminaire data: nominal power, colour temperature and luminous flux, stored in the driver's memory.

Every D4i node reads that data the same way. Socket plus driver together is called Zhaga-D4i: only that combination guarantees that node and luminaire work together without configuration.

Node on top, sensor underneath

The communication node sits on top. It talks wirelessly to the municipality's central management system, for example via LoRaWAN, NB-IoT or a mesh network, and controls the driver over DALI. A motion or daylight sensor fits underneath, raising the light when someone passes and lowering it on an empty cycle path.

What this delivers in practice:

• Dimming schedules per street: dropping to 50 percent between 23:00 and 05:00 puts six of roughly twelve burning hours a night at half power, which soon adds up to about a quarter less annual consumption.
• Faults visible immediately: the management system reports a failed luminaire before a resident calls.
• Maintenance based on actual burning hours instead of the calendar.
• No supplier lock-in: a node from another brand fits just as well.

Which VIA luminaires have DALI-2 and D4i

In the VIA range, the street luminaires in the DALI-2 group are fitted with a DALI-2 driver with D4i and AstroDIM: up to 40 W, 2700 K, up to 160 lm/W, IP66, type III optic and 10 kV surge protection. They tilt on a 60 mm column top or bracket and therefore fit directly on the 4 and 6 metre steel columns of TURRIS.

AstroDIM is the fallback: the driver derives the night from its own switching times and dims without a node or control cable. The installation works from day one and the municipality can add nodes later. The other VIA luminaires from 25 to 100 W have a DIP switch or a separate driver. If your specification calls for a Zhaga socket, request a quotation; we match the version to each project.

Practical points for the specification

• Check whether the specification demands Zhaga-D4i or only DALI-2; that determines which driver and which socket are needed.
• The column wiring does not change: live, neutral and earth run through the NEXUS column cut-out box, communication is wireless.
• Keep the 10 kV surge protection; a node contains electronics that will not survive a spike.
• Have a lighting calculation made for the lighting class in the specification, for example P4 with an average of 5 lux for a residential street, and record how far the dimming schedule may drop at night.

Frequently asked questions