By Alvin Wong, CEO of Innovative Green Power Sdn. Bhd.
Lately, many EV owners have reported their Miniature Circuit Breakers (MCBs) nuisance tripping repeatedly, especially on single-phase 7kW setups.
What Is Nuisance Tripping?
Nuisance tripping occurs when your MCB trips (switches off) even though there is no actual electrical fault. This interrupts your charging session and often leaves you frustrated.
Why Does Nuisance Tripping Happen?
It often comes down to poor quality MCBs that:
- Heat up excessively under continuous load near their rated capacity (such as charging at 32A for hours)
- Have lower tolerance against heat, voltage fluctuations, and inrush currents
- Use cheaper internal components that degrade quickly with daily use
On EV chargers, where charging can last 4 to 8 hours at near-full load, low-quality MCBs often weaken over time, leading to repeated tripping even though your charger and home wiring are in good condition.
Why Simply Replacing with the Same Low-Quality MCB Is Not a Solution
Many homeowners call their installer and claim warranty, only to replace it with another low-quality MCB from the same supplier. This often only delays the problem.
It is important to understand:
- Not all MCBs are built the same
- Rated capacity does not guarantee real-world endurance under EV charging conditions
- Continuous high-load applications like EV charging require high-quality, industrial-grade MCBs with better thermal management
How Should We Deal with It?
1. Choose High-Quality MCBs
Brands like Lovato and others known for consistent quality provide 10kA MCBs with robust internal components designed for endurance.
2. Proper Sizing
While your charger may use 32A, using an MCB rated for a slightly higher continuous tolerance, within safe regulatory allowances, can reduce nuisance tripping.
3. Confirm Your Wiring Health
Worn or undersized cables cause heat buildup, which can also trip MCBs. Always pair a good MCB with a well-sized, healthy wiring system.
4. Professional Installation and Testing
Have your system tested with a thermal camera to check for hotspots and ensure your MCB, wiring, and charger are all working in harmony.
The Bottom Line
Your EV charger deserves a reliable protection system, not just the cheapest part available. If you are experiencing repeated tripping, do not just replace it; replace with quality and test your system.
Let our obsession with quality protect your safety.
Because when it comes to EV charging and electrical systems, there is no room for compromise.
