In my previous article, we explained all there is on how to buy UEDCL Light, but have you ever paused to imagine the magic behind this system? From the moment you pay for units via your phone to loading them on the Yaka meter, which then connects to the grey box on the electric pole that actually Light your house.
History (From Paper Electricity Bills to Yaka and now Light)
Since 2011, seven years into UMEME’s concession to distribute and sell electricity in Uganda, the company introduced a prepaid metering system known as Yaka. Ugandans quickly adopted, moving away from the post-paid system, where UMEME staff had to physically visit every household each month, record readings on the meter box, and issue a paper invoice that customers cleared at banks or designated offices. Yaka promised convenience by allowing customers to pay upfront and monitor their own usage.
However, the system soon developed a reputation for being exploitative and unreliable; customers complained about frequent token errors, unexplained deductions, and inconsistent Yaka unit allocations without clear explanation. Payment options were also limited in the early years, requiring long queues at UMEME service centres and specific bank branches before mobile money integration around 2013 and 2014.
Come March 2025, when the Uganda Electricity Distribution Company (UEDCL) took over electricity distribution from UMEME, the first noticeable change was the rebranding of the Yaka system as Light. The prepaid tokens are now called Light Tokens, although many households still use the same meters labelled Yaka to load their units. On the surface, it seems like nothing more than entering a twenty-digit token on the meter keypad, but behind that simple act, sometimes tedious, is a much deeper process that we are here to break down.
Making Payment (Buying Light)
The process begins when you pay for electricity through MTN Mobile Money, Airtel Money, or directly at a bank. After entering your meter number and the amount you want to spend, this request does not simply get logged and approved on the spot. Instead, it is transmitted to UEDCL’s central servers through a secure digital communication link called an Application Programming Interface (API). This API acts as a bridge allowing two different computer systems, such as MTN’s payment platform and UEDCL’s electricity vending system, to exchange information in real-time and safely authorise transactions.
Verification and Light Unit Calculation
Once your payment is approved for UEDCL’s system, it is verified against your meter number. This verification checks whether the meter number is valid and registered, and whether the payment amount is sufficient to generate the Yaka-now-Light units. UEDCL then calculates the number of electricity units to assign to you. This calculation is not always fixed and depends on the tariff category to which you belong, such as domestic or commercial, and whether you qualify for lifeline units. Lifeline units are a small block of low-cost units offered to households with minimal consumption, covering the first 15 kilowatt-hours purchased in a month. The system also factors in standing charges and sometimes past usage, which explains why spending the same amount of money may not always give you the same number of units each time.
Light Token Generation
After confirming the calculation, UEDCL generates a twenty-digit Light Token specifically for your meter and encrypts it using international security standards, making it impossible to forge or guess. This token serves as a one-time password, mathematically linked to your meter number (cannot be transferred to another meter), and contains a hidden timestamp to prevent reuse. Keep reading… Once ready, UEDCL sends the token to you via SMS or the payment platform used.
Entering Light Token (Yaka)
At this point, you enter the twenty-digit token on the keypad inside your house. This device is called the Customer Interface Unit (CIU), not the Yaka or Light meter, as many people call it, because it is not the actual meter. The CIU, which looks like a small calculator and sometimes hangs on a wall, only lets you enter commands and view information. The real work happens in the Metering and Control Unit (MCU), the grey box installed on the electricity pole from which the main cables run to your home. The CIU and the MCU communicate using a method called Power Line Communication, sending the numbers you enter along the same wires that carry electricity until they reach the secure meter outside, where your power supply is activated.
Tip: For households using an external Customer Interface Unit (CIU) bought to replace a failed one, usually white with a power cable, you don’t always have to run to your neighbour to enter the token code when the power is out. As long as they have working batteries and are connected to a wall power socket, entering the token will communicate with the meter and restore your electricity, even if the main power is off.
Processings Inside the Meter (Grey Box) on the Electric Pole
When the Metering and Control Unit (MCU) on the pole receives the twenty-digit token, it immediately decrypts it using its built-in processor. How? The meter holds a secret key that matches the one UEDCL’s central system used to generate your token, allowing it to independently confirm whether the token is genuine. At the same time, it checks the timestamp to ensure the token is still valid and has not been used before. Once everything is verified, the meter closes an internal relay switch and adds the purchased units to your balance. Surprisingly, all of this happens offline; the meter does not need an internet connection to validate or load your token, as the intelligence is fully embedded in the device itself.
Using and Monitoring Electricity
From that moment, every active device in your home begins consuming units in real-time. The meter subtracts units based on the amount of electricity each appliance consumes. The keypad display shows your remaining balance, and when units drop below 15 kilowatt-hours, the meter beeps as a warning. If you don’t recharge, the units eventually hit zero, and the system automatically disconnects power. Once you purchase and load a new Light Token, the connection is restored instantly.
Although the name has changed from Yaka to Light, with UMEME now replaced by UEDCL, the experience for customers remains the same. You still buy tokens, enter a code, and monitor your usage, yet a simple token purchase actually triggers a highly coordinated process involving payment providers, UEDCL servers, encrypted token generation, and smart offline meters that ensure electricity reaches you fairly and reliably.
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