Re reading the other comments again , that perhaps explains the US receptacles as per LearJet9.
A lot of land where several single family houses are to be built. Apparently they install the electric (underground) service in advance. (Aruba, Dutch Caribbean)
120V-60Hz. I was unable to ascertain any further info.
Aruba, Bonaire and Curaçao are the Nederlandse Antillen, and it is very likely that Dutch switchgear was used here and I think 120 or 127 Volts is common there hence perhaps the US receptacles to make interchange with American equipment easier.
