Quick question regarding this error, whenever I switch off a fuse on our fuse board (recently the first floor lighting), I get this error, is that normal? The system sorts itself out as soon as the fuse is switched back on.
Electricity Meter Comm Fail
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The EM115 if that is what you have needs 3 sets of wire connections
mains L&N to power it
- & - to the inverter to give the inverter the readings
black and white to the CT clamp to get readings
https://midsummerwholesale.co.uk/pdfs/giv-ct-manual.pdf
I presume you mean a particular breaker only, in your case 1st floor lighting that must be being used to provide the L&N

Mine is the same, the EM115 is getting it's power from the circuit breaker next to it (downstairs lights) so if I turn that off the EM115 also turns off.
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Mine has its own MCB, its own switch and its own box on the wall. Treated like royalty. 🤣