Here’s the official diagram. L is live and N is neutral. Since the polarity of how Shelly 1 Plus is powered has no effect on the output relay, I’m wondering if it’s ok to swap L and N so that there’s no voltage on the SW terminal at all time. It worked in my experiment. Not an electrician here. May I ask for any suggestion on whether this is fine? Thanks!
Hi,
N (neutral) is not necessarily at 0V. And is some countries it is forbidden to only cut the neutral. You cut the phase (L/Live) or the phase + neutral (L+N) but never the neutral alone.
Furthermore, swapping L and N on this Shelly may lead unexpected behavior or incompatibility if you have 3x400V + N (so 230 between one phase and the neutral).
Indeed by swapping L and N you will not be able to “chain” neutral along several Shelly 1 Plus that will control circuits that are not on the same phase (or even if you place energy meter). At one moment, you will be lost in your wiring.
I hope I am understandable.
Best regards.
I am an Electrical Engineer.
The answer is NO, using a device against the manufacturer’s instructions is dangerous.
Why?
The designer of the switching power supply for the electronics likely included a drain capacitor to link parts of the low voltage side of the design to N, which is assumed to be ground-referenced in many countries (e.g. TNCS in the UK).
A relay with volt-free contacts may give some isolation, but ignoring the installation instructions means safety testing is invalid.
Doing the same Phase - Neutral reverse trick with something like a USB charger could easily be fatal (e.g. metal body of the USB-A socket referenced to Phase).
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Switches should always switch the line not the neutral.
I totally agree with technical and precise explanation of @FloatingBoater.
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