Electricity can cause injury in several ways, which include Electric Shocks, Burns and injury caused by violent movement as a result of electric shock. The effects of an Electric Current passing through any part of the body can exhibit various effects and severity including a tingling sensation, a severe jolt, complete muscular contraction and finally respiratory failure and death.

In most instances electric shocks occur when persons touch a live conductor and another part of their body is connected to earth potential. It may be that there is a damaged cable on an electrical applience and the operator is leaning agaist a wall whilst touching the exposed conductor. The reason behind this is that most electricity supply systems are deliberately connected to earth at some point and by touching the exposed conductor the person is completing the circuit through their body. An example of this not happening is when a bird pearches on a 20,000,000 volt pylon wire. Because the bird is only connected the the conductor and not earth the is no circuit so no current will flow.

To help understand how electricity can cause injury it is necessary to understand that in order to function the body requires a certain ammount of electrical energy. The muscular system is controlled by small currents in the order of 4 micro amps acting on the central nervous system. In order to grasp with the hand a small current as mentioned is sent down the nervous system to the required muscle which causes it to contract. The strength of the contraction or grasp will depend upon the amount of current supplied. To release the contracted muscle the current is removed which causes it to relax but a new signal must be sent to the corresponding release muscle to return the limb to its normal position. It is important to appreciate that the release muscles are not as strong as the grasping muscles. When a hand to hand electric shock is received , the arm muscles will react to the electric current in a similar way to the currents generated in the body. In practice if the current is in excess of 10 milli-amps the contracting muscles will over come the release muscles and invoulentary grasping will take place whilst the current continues to flow. Because this current is in excess of the normal control currents generated the muscles (hand ) will be unable to Let Go. Therefore this value is called the "Let Go value".