Non-ceramic (polymer, composite) insulators consist of a fiberglass core rod, weathershed housing, and metal end fittings. The housings generally are manufactured from polymeric materials. In service, the weathershed materials may be subject to degradation or aging due to harsh environmental conditions. One of the most commonly used laboratory tests to evaluate the performance of the weathershed materials is to employ fog chambers. Design and operational features of various fog chambers are reviewed in this paper, including size and main layout of fog chambers and their HV sources, data acquisition systems, systems for simultaneous visual observations and electrical measurements, and test cycles and techniques.