Caused by either AC or DC current. Current follows the path of least resistance and causes injury in areas other than the contact/entry site. They cannot be judged from the external injury alone. High voltage > 1,000 volts, low voltage < 1,000 volts and lightening.
Electrical burns are thermal burns from very high heat.
Burns caused by hot liquids. Water, oil, grease, tar, oil. Water at 140 degrees F, creates a deep burn in 3 seconds, but at 156 degrees F will cause the same injury in 1 second. (Coffee is 180 degrees F just brewed).
Circumferential burns should raise suspicion of non-accidental trauma.
Tar needs to be removed either with an adhesive remover solution or petroleum based dressings