When sourcing a new EV charger supplier, the first thing most buyers ask for is the specification sheet. Then you will find that the vast majority of EV charging stations feature

✅ AC 30mA + DC 6mA leakage protection

It has almost become a standard feature in today’s EV chargers.

But here’s the real question…
Are all A+6mA leakage protection systems actually the same?

The answer is: Not necessarily.

Meeting the same specification doesn’t always mean achieving the same performance.

The reliability of a 6mA DC leakage detection system depends on much more than the electronic circuit. One key factor that is often overlooked is the magnetic core inside the current sensing transformer.

What’s the difference?
• Pure iron cores
These are mainly used in cost-sensitive products where low manufacturing cost is the top priority. They can meet basic functional requirements, but their long-term stability is generally more limited, especially in demanding environments.
• Iron-based nanocrystalline cores
This is one of the most widely used solutions in today’s EV charging industry because it offers a strong balance between detection accuracy, stability, and cost. For many residential and commercial applications, they provide reliable performance when properly designed and manufactured.
• Cobalt-based amorphous cores
These are often chosen for premium EV chargers or projects requiring higher long-term reliability. Compared with conventional iron-based solutions, they typically offer better long-term sensitivity, lower temperature rise during continuous operation, stronger resistance to humidity and corrosion, and more stable performance over many years. The trade-off, however, is significantly higher material cost.

So, which one is the best?
There isn’t a universal answer.
The right choice depends on the installation environment, expected service life, product positioning, certification requirements, and the total cost of ownership—not simply the initial component cost.
A leakage protection system shouldn’t only work on the day it leaves the factory—it should continue performing reliably after years of operation.

At FUDA EVSE, we believe great engineering is about understanding what happens behind the specification sheet. Two chargers may both claim “AC 30mA + DC 6mA protection,” but the engineering behind that claim can be very different.

Have you ever compared two EV chargers with the same specifications but very different prices? What do you think makes the difference? Let’s discuss below.