1. An electrode holder comprising: a) an outer housing having a head portion and a handle portion, b) an electrode clamping assembly in the head portion and which comprises a moving jaw and a fixed jaw, the moving jaw being movable between an electrode clamping position and a release position, c) a rigid conducting element having a lower power cable attachment portion attachable directly or indirectly to power cable, an upper portion electrically engageable with the moving jaw, and a track portion, the rigid conducting element able to move between a power on position where the upper portion electrically engages with the moving jaw to provide power to the electrode and a power off position where the upper portion is in an electrically isolating position relative to the moving jaw, d) the moving jaw being locked into the electrode clamping position such that the moving jaw is unable to move to the release position while the rigid conducting element is electrically engaged with the moving jaw, e) an operating member having a portion extending from the housing and able to be operated by a person, the operating member having a travelling portion that travels along the track portion on the rigid conducting element, the travelling portion adapted to travel along the track portion from a first position where the travelling portion pushes and locks the rigid conducting element into the electrically engaged position thereby providing power to the electrode, and to a second position where the rigid conducting element can move to the electrically isolating position relative to the moving jaw, f) a biasing member to bias the rigid conducting element into the electrically isolating position such that when the travelling portion moves to the second position, the biasing member biases the rigid conducting element into the electrically isolating position, and g) a jaw release member which is operable from outside the housing to enable the jaws to be released such that the electrode can be removed or inserted between the jaws.