“Check CT Grid” Issue- How to Fix it?

Electric Vehicle Charging Points play a crucial role in the widespread adoption of electric vehicles, offering a convenient and efficient way to recharge. Zappi, a popular brand of EVCP, has gained attention for its innovative features.

However, like any technology, users may encounter challenges during installation or operation. One common issue reported by users is the “Check CT Grid” message displayed on the Zappi unit.

In this article, we will explore the possible reasons behind this message and the steps to troubleshoot and resolve the problem.

Understanding the “Check CT Grid” Message

The “Check CT Grid” message on a Zappi EVCP indicates an issue related to the Current Transformer (CT) grid.

CTs are devices that measure electrical current, and in the context of Zappi, they are integral to the charging process. The Zappi unit relies on these CTs to monitor and regulate the electric current flowing to the vehicle.

Possible Causes

CT Clamp Not Connected: The default configuration of the Zappi assumes that a CT clamp is connected. If the clamp is not installed, the unit may display the “Check CT Grid” message.

CT Configuration Settings: Zappi units come with default settings that assume the presence of a CT clamp. If the CT clamp is not connected, the user must access the CT configuration settings to disable the CT, allowing the Zappi to operate without it.

CT Wiring Issues: Problems with the wiring of the CTs, such as open circuits or incorrect connections, can trigger the “Check CT Grid” warning. Proper installation and connection of CTs are crucial for the Zappi unit to function correctly.

Incorrect Placement of the Grid CT: The grid CT is not positioned correctly. For accurate measurement of all power entering or leaving the property, the CT must be installed in a specific location. The ideal placement for the CT is on the live cable originating from the electricity meter. In many installations, especially when setting up EV chargers like Zappi, a typical practice is to bifurcate the supply at this juncture and introduce a new consumer unit (fuse box). The division of the cable is facilitated through the use of a “Henley Block”.

Important: EV battery replacement can cost $1000s. To avoid high-voltage battery replacement, there are some things you can do. Read this article to find out the 10 best ways to maximize EV battery life and save tons of money!

Troubleshooting Steps

Check the Manual: Start by consulting the Zappi user manual. The manual provides valuable information on the installation process, CT configuration, and troubleshooting steps. Users should pay special attention to sections related to CT settings.

Accessing CT Configuration Settings: To resolve the “Check CT Grid” issue, users need to access the Zappi unit’s advanced settings. This typically involves entering a code (e.g., 0000) and navigating to the CT configuration section. Here, users can disable CT1, CT2, and CT3, which are default settings assuming CT clamps are connected.

Consulting Zappi Support: If troubleshooting on your own proves challenging, consider reaching out to Zappi support. While this might involve waiting for assistance, the support team can provide guidance tailored to your specific situation.

Also read: EV Battery in Hot Temperature: 5 Things to Know


The “Check CT Grid” message on a Zappi EVCP can be a common concern, but it is a manageable issue with the right troubleshooting steps.

By understanding the potential causes, consulting the user manual, and following the guidance provided by experienced users and support resources, Zappi owners can resolve this issue and continue enjoying the benefits of efficient and reliable electric vehicle charging.

Remember, a well-functioning CT system is crucial for the Zappi unit to optimize charging performance and contribute to the seamless integration of electric vehicles into our daily lives