It is not a fault. Singapore mandates the strictest residual-current threshold in the world, and rain makes solar leak. Here is why — and what to do when it happens.
Singapore is one of only two countries that mandate a 30 mA residual-current threshold for homes. A breaker set that low reacts to leakage most other countries would simply ignore.
Every circuit leaks a tiny current to earth. Wet panels leak a little more. Add the two together and a 30 mA breaker can be pushed over its limit. Drag from dry to heavy rain and watch it happen.
Rain wets the PV arrayMoisture gives the array's normal leakage an easier path to earth.
DryHousehold circuits keep leakingFridge, air-con, lights and plugs leak a small amount all the time.
12.0 mAThe two add upThe RCCB does not care where leakage comes from. It measures the total.
18.4 mA30 mA breached → tripThe breaker opens and cuts power to whatever sits behind it.
HoldingIf it tripped in rain, solar resumes once the panels have enough sunlight.
Active thunderstorm at trip time? It is almost always rain-related.
Or it will not stay on? Contact FOMO Support for a site inspection.
The inverter catches leakage internally before it reaches the RCCB, keeping the system generating in wet weather. Available on some inverter models only.
Carried out with full homeowner consent and a clear understanding of the regulatory position.
Yes. Singapore is one of only two countries mandating 30 mA for residential. Trips during wet weather are expected, not unusual.
Unlikely if trips always coincide with rain. FOMO cross-checks weather against each trip. Dry-weather trips lead to a site inspection.
No. 100 mA is still a very small current — even accidental contact only causes a minor sensation. Singapore's 30 mA rule is precautionary.
If solar has its own RCCB, only solar drops and the house stays powered. If it is shared, the whole house cuts. FOMO installs a separate solar RCCB where possible.
Yes. The inverter physically disables its contactors — a real circuit gap, no fire risk. Insulation is monitored continuously; above 1 MΩ is healthy.
Usually the same event. The inverter logs 'Grid Failure' when it loses grid, which is exactly what happens when the RCCB opens.
Everything on this page, condensed into a single sheet you can save or forward. Prepared by the FOMO Energy Solar O&M team.
A trip in dry weather is worth a look. Send us the date and time, and our O&M team will check it against the inverter logs.
