Positive voltage of an electronic device touching the outter metallic casing

[beeboopbeep]

Hi everyone,

I was wondering if there are any safety concerns with the device and any concerns in the environment if the device's +5 V is touching an aluminum casing which will be exposed to the user. Please assume that there is no way for the device ground to somehow touch this +5 V. Also, the internal source resistance of the +5 V source will be large enough so that only max current of ~50 mA can be output when shorted with ground.

My assumption is that nothing will happen since the +5 V and its ground will be well insulated and this 'floating' +5 V will have no way to travel to ground or any parts of the device traces unless the user punctures the device accidentally and shorts something.

Here is a photo to better illustrate the device structure (https://imgur.com/a/ukCvaS2).

Thanks!

[SmokedComponent]

If the device has own isolated supply then it doesn't matter - there is no circuit if the device casing touches some other grounded object.
You can declare that internal +5V as external ground and device runs on -5V, as seen from the outside world.

[JustMeHere]

Cars used to be positive ground.

There is much debate as to why it was changed.  My guess is NPN transistors had a good bit to do with it.   Low side switching is cheaper.

[langwadt]

Cars used to be positive ground.

There is much debate as to why it was changed.  My guess is NPN transistors had a good bit to do with it.   Low side switching is cheaper.

if that was the case we should have stuck with positive ground, that way you only need one low side switched wire to each load. With negative ground you need two wires, positive supply and a switched ground to each load