Hi folks, can anyone tell me what this means "Compatible with QO plug-on neutral load centers only". My Square D load center has a neutral bus bar... I don't know anything about a "plug-on" neutral. I just ran a couple new circuits to put outlets on an exterior wall beneath a lean-to on the side of my barn and the GFCI outlets that I bought do not fit the weather tight enclosures (they fit the box but since the spring loaded lids are separated (one for each of the outlets) the shape of the GFCI outlet doesn't allow them to close properly). I wound up installing standard 20 amp duplex outlets in the boxes and the lids fit perfectly now but I want GFCI protection for them since they're on the outside... I saw this breaker without a pig tail and thought I might be able to use a couple of these instead of the GFCI outlets. I've installed these before but it was the ones with the pig tail; will this work?.... would like to hear your thoughts.