Is a heating cartridge supposed to be electrically isolated?

Hello guys.

I’d like to ask you if you’ve ever measured the voltage across different parts of your machines. I found out that between my extruder block and ground, there’s an 8 V voltage difference. Checking components, I discovered that the heating cartridge is leaking some voltage to the aluminum block in the hotend.

My question then is: is the cartride supposed to be electrically isolated from ground? Or is it mine faulty?