Evaluating the quality of electrical wires used for residential building wiring in Delta State, Nigeria

The utilization of counterfeit and substandard building materials for residential building construction had become a major concern, due to the hazards the occupants of those buildings are being subjected to. This research was carried out to appraise the quality of electrical wires used for residential building wiring in Delta State, Nigeria, and to also investigate the reasons why property developers still use these substandard materials despite the glaring negative consequences. Three commonly used electrical wire sizes (1.5, 2.5 and 4 mm2) for residential building electrical wiring were randomly selected within the Delta state, and their electrical properties (electrical resistance and electrical resistivity) and mechanical properties (area, tensile strength, and tensile strain) were determined following the Institute of Electrical and Electronics Engineers (IEEE 400), Nigeria Industrial Standard (NIS), and America Standard Testing Material (ASTM) International recommended procedures; also, well-structured questionnaires were administered to four groups of respondents. The findings indicated that the mechanical and electrical properties of most electrical wires, used for residential building wiring in Delta State failed to meet NIS standards. Across the five sampling locations, the mean electrical resistivity of the 1.5 mm2 wire ranged between 2.04±0.07x10-7 and 2.09±0.08x10-7 Ωmm, while the 2.5 mm2 wire's mean electrical resistivity varied from 1.90±0.06x10-7 to 1.97±0.13 x10-7 Ωmm, and the 4 mm2 wire’s mean electrical resistivity varied from 1.75±0.08 x10-7 to 1.87±0.06 x10-7 Ωmm. Also, across the five sampling locations, the mean tensile strength of the 1.5 mm2 wire ranged between 144.1 and 163.3 MPa, while the 2.5 mm2 wire's mean tensile strength varied from 163.2 to 177.4 MPa, and the 4 mm2 wire’s mean tensile strength varied from 169.4±20.6 to 185.4±17.2 MPa. Furthermore, the analysis of variance indicated that sampling location had no significant effect on the wires' mechanical and electrical properties (p≤0.05); portraying that this fraudulent practice is widespread across the state. The analysis of the questionnaire results confirmed that financial constraints and inappropriate actions of many building contractors were the major contributing factors to the utilization of substandard wires for residential building wiring in Nigeria. Based on this study's findings, it is recommended that standard regulatory agencies should step up their efforts against substandard building materials, to avoid its impending danger in Nigeria.