Part 1: The Breaker That Tripped Weeks Apart

Intermittent faults are rarely convenient.

Following an LED lighting upgrade in a 28-year-old building, one of the newly RCBO-protected lighting circuits began tripping at seemingly random intervals — sometimes with weeks between trips.  Other times, just hours.

We had already uncovered a faulty light switch in one room immediately the new breakers were installed. That fault pattern gave us a clear indication of where to look. This time, there was no such pattern.  No particular switch behaviour or operating condition could be linked to the trips.

The fault

The problem was traced to a fluorescent emergency light that had deteriorated with age but was still appearing to operate normally.  The emergency lighting in the room shared a neutral with the general lighting so the trip took out the new LED general lights.

The takeaway

The easiest assumption was that newly upgraded lighting tripping the circuit meant there was an issue with the new lighting.

But it was introduction of more sensitive RCBO protection into a 28-year-old electrical installation that exposed a pre-existing a problem.

And this wasn’t the only example we found at the site. In Part 2, another investigation of tripping breakers revealed an even more obscure cause.