I'm looking into temperature switches and came across this type which warns against shorts and instructs you to use a provided plastic sleeve to prevent this. Although I'm linking to a specific product here please consider it just as an example of this type (of which there seem to be many out there).
It is described as:
"60°C Normally Open Thermostat Temperature Control Switch ... 250V 5A N.O Thermal Protector Metal Bimetal Temperature Controller"
Here's the warning:
It also separately says "Attention: Do not remove the plastic shell when using, and beware of electric leakage."
I'd like to understand exactly what could short to what. I wouldn't have thought that the outer metal shell would be conductive to the leads, but is that actually what this warning is about? If not, what are they warning against?
I suppose one lead might have continuity with the shell... but if that is the case why would they use conductive packaging at all? (Cheapness?)
Aside from the risk of a short causing a problem, I would ideally want the metal case to be directly on the object whose temperature is being measured for the fastest response without any insulating effect of the plastic.