Consumer unit RCBO tripping

Our PV/AIO was installed approx 4 weeks ago. Been working fine, but a couple of times our downstairs lighting circuit has tripped in the main consumer unit.

I appreciate that its not likely anything to do with the solar/battery install, but wondered if an underlying problem with our consumer unit has been exposed. I’m especially wondering about earth leakage as the new AIO has had a separate earth rod installed. Its very random and to my knowledge its only happened on the odd sunny day bizarrely - could be a major coincidence.

Any help with fault finding would be much appreciated. As its so random I’m loath to call in an electrician at this stage until I can pinpoint the cause.

Issues I have considered are:

  1. Overloading of lighting circuit, but it’s happening with no lights on
  2. Earth leakage issue
  3. Over sensitive RCBO

…anything else to consider…?

RCBOs are specifically used to prevent different circuits causing each other to trip, an RCD covering multiple circuits could cause this problem. The earth rod should be for the whole installation not just the AIO. It provides an additional route to earth in the case of a fault, it can’t induce additional earth leakage.

If the trips occurred with no lights turned on, I suggest calling an electrician.

Yes, the earth rod covers the whole installation. And it’s only one circuit that trips.

I’m just trying to isolate the possible causes, especially as it’s intermittent. I have isolated the outside lights and have had no more trips today. Will monitor the situation over the next few days.

Hi Couplands, Your problem could well be resolved by now but I recently had a problem with a lighting circuit tripping an RCBO. In the end I found out that a shower room ventilator pipe wasn’t thermally insulated in the loft and the hot steamy air was condencing in the pipe and running back into the fan and causing the RCBO to trip, even when the lights were turned off. Could your outdoor lighting be allowing waster ingress?

Inverters may produce surge currents. It’s normal to use a different type of RCD/RCBO on inverter-based equipment to that used on equipment which runs from the grid and uses the AC direct. My heat pump uses an inverter and has a B curve type A RCBO (FuseBox RTA1063230B). The GivEnergy/solar PV kit has a type A RCD (Niglon RCD2-63/30-A). Both have worked fine without tripping.