Advanced Energy's DC String Combiner Box provides a means of combining multiple positive or negative grounded source circuits into a single DC output. With no hardware changes required for positive or negative grounded systems, AE combiner boxes are ideally suited for bi-polar or mono-polar applications. Each source circuit is fused separately using a touch- safe fuse holder. The combiner box allows for fail-safe operation of the system in the unlikely event that a problem with a source circuit leads to abnormally high current. In addition, the combiner box provides a convenient means of accessing the DC portion of a PV system for routine maintenance and troubleshooting.