Leviton Z-wave 800 Switch - ZW15S - stray voltage of 5V AC?

Hardware
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1

This is more of a electrical/electronics insulation/induction question.
I have this ZW15S switch(manual), and was trying to install it.
The switch is now hanging out in the air, outside of the connection box, just held by the wires & not touching anything.
The wires so far connected are Neutral, Line & Load. It is paired & works to control a lamp, either through home assistant or by tapping the switch itself
The ground is not connected yet.

What I did now was measuring the potential difference between the switch’s metallic wall mounting tab and the bare grounding wire in the box…that is one probe on the switch’s metal part of the body & other on the bare ground wire coming into the electrical box.

The multi meter reads 5V AC… I wanted to know if it is normal or not and how this can be explained.
Thanks!

2

It’s hard to say without knowing how the switch is constructed. You may simply be demonstrating why a ground conductor is required for safety. If you look at your breaker box, neutral and ground connect to the exact same thing, so why 2 conductors? Neutral carries current under normal circumstances, and since all conductors have resistance, a voltage is developed. Ground conductors are intended to carry current only during a fault, and even then, likely for a short time as you usually trip a breaker.