Is my laptop grounded when connected to a grounded monitor?

[land.of.academic.pressure]

Hi there,

My ThinkPad Yoga 460 is connected to mains power through the two-pronged ungrounded North American power supply included in the box. The ThinkPad is also connected to a monitor via mini DisplayPort. The monitor has a built-in power supply and is grounded with a three-pronged cable. Will the connection between the monitor and the ThinkPad result in the ThinkPad being grounded as well? Will the grounding extend to connected USB devices as well? Thanks.

 

[Scottray]

The third prong in the USA is to provide safety, especially for appliances that are enclosed in metal cabinets. If a short occurs between the neutral and the ground, it will cause the circuit breaker to open and thus eliminate the risk of electrocution. Other appliance can be built safely with double insulation methods and don't require the third prong. So, 2 or 3 prongs are used depending on how a device is made and the safety requirements it needs to meet.

For your specific questions, no - the monitor's third prong does not provide grounding to the laptop. Both are referenced to neutral and designed for the appropriate fault protection. DP and USB signals are DC signals that are referenced to the power supplies of each device and ultimately to the neutral on the AC side of the power supplies.