Electrical safety and touch voltage design

Abstract

The provision of safe and reliable means to afford protection against electric shock in the built environment is deemed one of the most important design elements for electrical services engineers who design low voltage electrical installations to conform to BS7671: 2008 (17th edition IEE Wiring Regulations) and ET 101:2008. The fact that, domestic properties rank as one of the leading locations for electrical injury and death, and domestic electrical installations lack routine inspection and scheduled maintenance in a European environment where an ageing housing stock exists in many countries, highlights the growing concerns for domestic electrical safety. However, by performing a value-engineering design through the implementation of residual current devices and a ‘low touch voltage’ design, a higher level of domestic electrical safety can be attained. Practical application: The ‘touch voltage simulator’ Excel application presented is a powerful tool for designers and installers of low voltage electrical installations to test and evaluate the resulting touch voltage for various design parameters. It can also be used to identify the sensitivity of resulting touch voltages to any variations in the four main design parameters U OC, Ze, R1 and R2. The ‘interactive touch voltage charts’ can plot interactive graphs, which can be used as visual aids for engineers to ascertain how the touch voltage could fluctuate with variations in the major design parameters at the design stage.