In this study, a protection-pipe system has been developed for the protection of undersea electricity cable layout along shoreline with medium deep water. The protection pipes are made of cast-iron alloys while the dimensions are designed corresponding to the balk diameter of electricity cables. The water depth of the area with cable layout is ranged from several meters to a hundred meters, where berthing anchoring from commercial ships and towing operation from fishing boats are constantly found. Therefore, to make sure that the protection pipe can work dependably against the loadings mainly from the operation as was mentioned, both analytical analysis and experimental tests were carried out. In the experimental studies, the full-scale model of several sets of protection-pipe system was tested for impact loadings. It was found from the results of both the analysis and experimental tests that the protection-pipes are able to meet the requirements of the local power company TPC set for the cable layout under seawater.