Hi All,

The RCBO that supplies the compressor in my treatment plant tripped randomly the other day. As I have been doing some maintenance on it and subsequently monitoring it I noticed quite quickly. This was the first time it had tripped since installation 20 months ago and hasn't tripped again.

The RCBO is in a CU in the detached garage which itself is supplied via sub main direct off the incoming supply to the house.

So I thought some sort of monitoring device might be prudent. Originally I thought I could utilise a non maintained emergency light that I have kicking about but realised it wouldn't have enough life if the supply failed at night. I go into the garage daily but not necessarily first thing. Has anyone any (low cost) suggestions?

I'm thinking maybe batten lampholder, red lamp, supply from garage lighting circuit and, what, an NC relay with a supply from the outgoing terminals of the plant's RCBO?

We're not talking life critical, hospital standard here, but if the supply's off too long my poor little microbes suffer!

Thanks for any suggestions!