i hv a doubt...in three prong plug...there is hot neutral and ground wire.......through ground we can make ground connection to metal frame to the applicance...if hot wire touches the metal ground connection will shorted so user is safe......but in two prong plug.IT IS NOT POSSIBLE...NOW A DAYS WE ARE ASLO USING TWO PRONG ONE.....HOW TO GET RID OFF THIS PROBLEM...PLZ HELP ME.........

 

Two-pronged plugs are normally only allowed on double insulated equipment. Where the possibility exists for the active wire to dislodge and make contact with an exposed or accessible metal part of the equipment then the earth prong is mandatory with all exposed metallic surfaces bonded to that earth point.

Hot neutral is is not normal with conventional M.E.N (multiple earthed neutral) installations.

It's not clear to me in reading your post what your actual problem is.

 

The ground wire is used in devices with metal cases were there might be risk to the user of being electrocuted. However most devices these days are either well insulated or have a non-conducting plastic case so there isn't need for there to be a ground wire anymore. As far as I understand your question, if you want to use a two-pin-plug device on a three pin socket-it is perfectly OK.

 

You can add a ground rod if you need a ground for protection.

This is not very difficult if the outlet is on a first floor exterior wall.

You can run the ground rod into the Earth and run the ground wire to the outlet box and replace the outlet with a 3 prong.

If this is a design task, the double-insulated route is the way to go.