Hello everyone,
I have a question about the wiring of the VM-3P75CT. According to the instructions, you should connect N + L1 with a switch or circuit breaker. But why not L2 + L3?
Thanks for your answers in advance.
Cause device is powered from L1, there no load on L2/L3
Whether there is a load on it or not is irrelevant in my opinion.
But the cable from the grid is usually 10mm². And 10mm² does not fit into the VM-3P75CT. And a reduction in cross-section is only permitted if there is a circuit breaker in between.
Since there’s no (internal) load on L2/L3, those are not considered a consumer. They’re only connected for voltage sensing, not for transporting current or powering the meter and thus don’t need to be fused.
If you’re the cautious kind, nobody will prevent you from playing it extra safe and putting fuses on L2 and L3.
I know this is what I’m doing, even if it’s just to simplify connecting the thin wires.
Connecting thin wires and thick wires to the same side of a breaker is tricky.
Putting a fuse or breaker on N/L1/L2/L3 makes it easier to connect them and is aesthetically more pleasing, but not technically mandatory.
HTH
“technically not mandatory” for a reduction in cross-section? Sorry, there should always be a circuit breaker in between. Whether there is a load or not.
Wires in meters are used only to measure actual voltage on lines and network frequency. That’s why you don’t have 10mm2 connectors, cause your house loads are not going through a meter, but only something like 1-1.5mm2 (I don’t remember the actual size). The device is powered from L1, so it’s recommended that the device be protected.
When reducing the cross section there should be a fuse if the fuse upstream of the high section wire is too much for the lower section wire, and this only for load carrying wires - not for sensing wires as there will never be any current flowing through those.
But as stated: you’re completely free to add the extra fuses on L2 and L3.