To bring some closure to this:
I continued with the “manual” strategy for a while, turning off the Eskom input when going to bed, putting it up in the morning. During the day I left it alone, and didn’t have any trips.
Of course, the one night I forgot to do it, it tripped, but this time with an Error 8, which was confusing.
From then on, it would constantly trip with Error 8 whenever Eskom power was resynced by the Multi. Manually tripping Eskom, and managing my battery levels carefully (I can get from 10pm to 7am and go from 95% to 25% most nights) allowed me to at least sleep through the nights.
@JacoDeJongh 's team were coming to Cape Town so I asked them to come around when they were here. Of course, they day they arrived, it declined to trip. Of course.
We tried and tried, but it behaved perfectly.
As a last resort, they opened up the DB, and found pretty much all the earths on the light circuits (ie the circuits not going through an earth leakage) were loose. Like, very loose. Also, a neutral on that circuit was loose.
According to Jaco, this is almost certainly the cause of the inconsistent tripping, both error 8 and error 11.
Since they fixed the situation, 2 weeks ago, I haven’t had any issues.
I’ll be honest, I’ve avoided this post mainly because I’ve become quite superstitious and convinced that as soon as I post it the system will trip tonight, so… 