How do I know if my power supply is grounded?

You can use a multimeter to test your outlets for proper grounding.

1. Connect the multimeter's probes to the main body of the meter. ...
2. Turn the multimeter to the highest AC voltage range available. ...
3. Insert the two test leads into the hot and neutral parts of the outlet. ...
4. Remove the black lead and put it in the ground outlet.

Shenzhenshi Zhenhuan Electronic Co.,Ltd was founded in 2008, specialize in external power adaptor, ac dc adapter, Outdoor Waterproof Power Supply, led driver, Power Transformer, switching power supply, dimmable or non-dimmable LED Drivers and Battery Charger in Shenzhen, China. 

Zhenhuan is one high quality power supply manufacturer, we also have own brand  KSPOWER, and our products of power range from output 4.2W to 384W (output voltage 4.2V to 48V, output current 0.2A to 20A) a total of 1000 kinds of models and come with safety regulation standards: IEC/EN 62368, IEC/EN 61558, IEC/EN 61347, UL/cUL 62368, UL/cUL ETL/cETL 8750, UL/cUL1310 CLASS 2 and in full compliance with UL/cUL ETL/cETL RU/cRU CE ROHS SAA C-TICK KC KCC GS TUV FCC CB NOM CCC PSE CB certifications for global markets.