Temporary electrical installations power construction site offices, lighting, and equipment before the permanent supply is commissioned. These systems are exposed to weather, physical damage, and constantly changing site conditions. A poorly installed or maintained temporary supply can cause electrocution, fire, and extended project shutdowns. This talk covers the standards and checks for temporary electrical installations on site.
Key Hazards
Electrocution from damaged temporary cables or poorly connected distribution boards
Fire from overloaded circuits or water ingress into temporary switchgear
Electric shock from unprotected 230V outlets without RCD protection
Power failure affecting safety-critical systems such as lighting and pumps
Control Measures
Ensure temporary installations are designed and installed by a competent electrician to BS 7671.
Protect all socket outlets with 30mA RCDs and test them at least monthly using the test button.
Use 110V centre-tapped earth supplies for all portable tools and equipment on the construction site.
Route temporary cables at height or in protected conduit to prevent physical damage from plant.
Ensure all distribution boards are weatherproof rated and locked to prevent unauthorised access.
Inspect the temporary installation regularly and after any event that could have caused damage.
Label all circuits clearly on the distribution board with the area or equipment they supply.
Provide emergency lighting on backup supply for escape routes and high-risk work areas.
Record all inspections, tests, and modifications in the temporary installation log for the project.
Remember
Temporary installations must be designed and installed by a competent electrician to BS 7671
All 230V socket outlets must be protected by 30mA RCDs tested at least monthly on site
Use 110V centre-tapped earth supplies for all portable tools and equipment across the site
Route cables at height or in protected conduit to prevent damage from plant and vehicles
Distribution boards must be weatherproof, locked, and clearly labelled for every circuit
Record all inspections, tests, and modifications in the temporary installation log
Applicable Legislation: Electricity at Work Regulations 1989 · BS 7671 (IET Wiring Regulations) · BS 7375 (Distribution of Electricity on Construction Sites) · Health and Safety at Work etc. Act 1974