How do circuit 1 and circuit 2 differ? Choosing the right setup for a home EV Charger installation

Circuit 1 is a direct cable run from the main panel to the charger, suited to homes with a 5/100 or 30/100 meter or larger that want to charge at maximum power. Circuit 2 separates the charger circuit from the household supply without upgrading the meter, suiting typical homes. Both use an RCD Type B and the same standard-compliant earthing system.

Installing an EV charger at home is not just a matter of fixing the unit to the wall. A charger draws power continuously for several hours each session, so the electrical system must be able to support it safely from the outset. EV Easy Thailand recommends 2 types of electrical circuit to suit each home. This guide sums up the differences between the two in one place, compiled from our installation team's articles on Circuit 1 and Circuit 2, with examples from real installations

Where do circuit 1 and circuit 2 differ?

The figures in this table come from the circuit 1 and circuit 2 articles published by our installation team. The actual equipment sizes for each home may differ, depending on the site survey, e.g. the cable run distance, the size of the existing consumer unit and the power of the chosen charger.

Who is circuit 1 for?

Circuit 1 (Maximum Safety & Power Circuit) suits homes with a high available power supply, or that plan to use an EV for the long term. It is designed to support charging at the charger's maximum power, according to the number of phases in the home, both 1 phase and 3 phase. The heart of this circuit is a direct cable run from the home's main panel to the charger installation point only. Think of it as an express lane where current flows to the charger without disturbing other circuits in the home.

This circuit uses an extra-large cable of 35 sq.mm or more to reduce heat build-up in the cable when drawing high power continuously for long periods, and a dedicated 40A sub-breaker just for the charger as the first line of protection for the unit. Real installation examples include Model U Gen 2 7.4 kW, circuit 1 with DLB, Sai Mai district and Circuit 1 installation with storage cabinet and Model U

Who is circuit 2 for?

Circuit 2 (Standard Setup) was developed as the standard option for typical homes, most of which were not originally designed to carry high loads. Its key advantage is that there is no need to upgrade the meter or do extensive rewiring, yet the charger circuit is still clearly separated from the existing electrical system. This reduces the impact on household power and prevents voltage drops when many electrical appliances are used at the same time.

• 50A main breaker controlling the overall load of the whole home
• Dedicated 40A sub-breaker just for the charger, keeping charging stable without disturbing other circuits
• 16 sq.mm cable that supports continuous power delivery for many hours without heat build-up
• Standard-compliant earthing system (Ground Rod) that safely discharges fault current to earth
• RCD Type B protecting against both AC and DC earth leakage

Among the projects published on this website, more are listed as circuit 2 than circuit 1. Examples include Model U Gen 2 7.4 kW, circuit 2, Lak Si district Model Q 7kW, circuit 2 with storage cabinet, Pathum Thani province and Model U Gen 2, circuit 2 with Max storage cabinet

Why do both circuits need an RCD Type B?

EV charging systems can leak direct current (DC), which an ordinary RCD cannot detect. An RCD Type B is designed to detect both AC and DC leakage current, which is why it is the standard our team uses in every circuit. Our FAQ recommends a 40A breaker with an RCD Type B for 32A chargers (7.4 kW or 22 kW), and a 20A breaker with an RCD Type B for 16A chargers (11 kW or 16A portable chargers). Read more in What is an RCD earth leakage protection system?

Related equipment is available on the product pages

• RCCB Tongou x EV Easy 40A 30mA Type B (2-pole) for 1-phase power
• RCCB Tongou x EV Easy Type B (4-pole) for 3-phase power
• Under-/over-voltage protector with display

Which circuit should I choose if my home has a small meter?

Our installation team's circuit 1 article states that for homes with a small meter, such as 15/45, circuit 2 is the more standard and flexible option, but this must be considered together with the charger's power. According to our FAQ, a 15/45 meter can handle a continuous current of around 20A, which may not be enough for a 32A charger, with a risk of the meter tripping. That is why our installation team always surveys the site first and then proposes a safe solution, such as replacing the meter, adjusting the charger's power, or using a charger with load management. Read more in What is DLB? and What size electricity meter do you need to install an EV charger?

Is the installation covered by a warranty?

Yes. For EV Easy installation work, the warranty period depends on the product model; see the warranty period for each model on its product page. This is separate from the warranty on the charger unit itself, whose period depends on the model (see each model's product page). After installation, our team checks the electrical system and tests charging with the customer's car before handover.

Summary: how to choose a circuit?

If your home has a 5/100 or 30/100 meter or larger and you want to charge at maximum power in the long term, circuit 1 offers the greatest stability. If yours is a typical home and you would rather not upgrade the meter, circuit 2 is safe, practical and the option most homes choose. Both use an RCD Type B and the same standard-compliant earthing. The most reliable way to decide is to have our installation team survey the site. See all installation steps and options on our Installation services page, or choose a charger that suits your circuit in the guide Choosing a 7.4, 11 or 22 kW charger