The goal of this research is to improve the quality of polyethylene cable spacer using proper design, robust materials, and consistent manufacturing processes resulting in HDPE cable spacer prototype. Field tests have been conducted in 3 designated areas which are 1) high air-borne salinity coastal area at Koh Samui, Surat Thani, 2) high micro-particulates, air polluted area at Na Phralan, Saraburi and 3) high humidity area at Doi Inthanon National Park, Chiangmai. The results show that, after 360 days in commission, the mechanical properties of the cable spacers currently used in the PEA distribution system drop dramatically and the degradations by UV are obvious, while prototype cable spacers show no trace of photo and thermal degradation all through the test period. The maximum loads of the prototype are stable. In term of flammability, new material used in the prototype can reduce the burning rate by 16%. All examined cable spacers still surpass electrical properties requirements after 360 days in service.