Obviously you need to be careful around someone who has been shocked so you don’t put yourself at risk. If he is still touching the electric source, cut off the power. Get a broom handle or other length of dry wood, stand on a dry rubber mat or pile of newspapers, and use the wood to move him away from the source.  

The original tip next offers medical advice, which I’m not fond of posting here. Follow these suggestions at your own discretion:

“Once he is out of harm's way, douse burning clothes with a towel, blanket or fire blanket. If he is unconscious on the ground, check his breathing. If this has stopped, apply artificial respiration and, if necessary and you know how, chest compression. When he starts breathing, lay him in the recovery position.

Check the casualty for burns. Treat these with cold water and cover them with sterile dressings. Call an ambulance.”