Electronic – Why is earth pin absent in phone chargers plugs but present in laptop ac plugs


Both mobile phones and laptop get dc voltage from ac source for charging.These chargers have transformer for isolation and rectifier + filter if i am not wrong.I guess the amount of output dc and charging current may vary.

Why do modern mobile chargers use only 2pin plug or 3pin with dummy earth pin? But
Laptop chargers use 3pin plugs with earth pin?

Mobile charger Nokia

Laptop plug

Best Answer

In the EU (and probably in many/most other regions too) appliances that are double insulated, or which work from safe extra low voltages (SELV) are not required to be connected to protective earth.

In your first example, if the "wall-wart" is properly constructed, a single fault would not result in dangerous voltages being present on the low-voltage† lead from the wall-wart to the phone (and thence to you)

See also

† Typically 5V nowadays and maybe 1000 mA or so for a phone charger.