An electrical contractor created a short circuit during a battery installation. In 2016, we received a called for assistance from one of our customers when their “embedded” electrical contractor installed two battery systems in a new unit at their refinery. During one of the installations, the electrical contractor inadvertently connected cell #1 to cell #60 in one of the 120-vdc battery strings. Fortunately for the installer, there was a loose connection between cell # 39 and cell #40 further down the string. This loose connection acted as a fuse for the short. Unfortunately, this did result in the disintegration of the connector nut and bolt hardware, turning the parts into shrapnel. No one was injured during the event but five of the cells were damage requiring replacement to get the string in service. During the initial call, the customer asked us to assess the battery damage and to get their system back in service as soon as possible.