Connecting jumper cables: the effectiveness of pictorial warnings
Each year, people are injured improperly jump starting their vehicle. They connect booster cables by incorrectly attaching them to the four battery terminals (i.e., positive to positive and negative to negative). These occurrences suggest the correct procedure is not commonly known (De Puy, 1990). The correct connection involves making the last connection for the car with the dead battery to an earth away from the battery. This procedure avoids having a spark ignite hydrogen gas from the battery, possibly causing an explosion and release of sulphuric acid.