I have a Microsoft Surface Pro tablet which, when charging from the included power adapter, gives a slight tingling feeling when touching anywhere on the Magnesium shell.
This is a commonly reported problem with the Surface Pro and Microsoft are willing to replace affected units free of charge.
Out of curiosity, I would like to measure the voltage on the case with respect to ground. The AC adapter is a 2-prong device which uses a IEC standard figure-8/shotgun connector (no ground pin) and outputs both 12V and 5V DC.
If I take a multimeter and connect one lead to ground, and the other to the case of the tablet, will I damage either the multimeter or the tablet? My understanding is that the voltmeter input is a very high impedance and as such a negligible current should flow.
Best Answer
AC probing is safe so long as your multimeter is rated for the full AC mains voltage you'll be playing with, and the probes that you'll be using are insulation-rated for that voltage as well. Most reasonable-quality multimeters are OK for 120VAC work. Make sure the probe wire insulation doesn't have any breaks in it.
The meter will present a voltage measurement resistance in the megohm range, so there's no real risk of damaging anything (yourself, the meter or the tablet).