A site transformer is a portable isolation step-down transformer, widely used for temporary power supply on construction sites. It is also called a construction safety transformer, which complies with UK HSE electrical safety requirements.
It converts 230V/240V mains supply into 110V output with a centre-tapped earth (CTE) winding design. Thanks to this structure, each live conductor only has 55V to earth. When cable damage or accidental contact occurs, the touch voltage is limited to 55V, greatly reducing the risk of fatal electric shock. Meanwhile, the primary and secondary windings are electrically isolated, preventing fault current from feeding back to the mains circuit.
Typical site transformers are fitted with robust yellow casings, usually IP44 rated for dust and splash resistance. Built-in thermal overload protection and circuit breakers cut off power automatically during overload or overheating. Common capacities range from 1.5kVA up to 10kVA, equipped with multiple 16A and 32A sockets to power electric drills, angle grinders, site lights and other handheld power tools.
This type of transformer is not an auto-transformer. It is dedicated to construction, renovation and outdoor maintenance work, offering reliable low-risk power for on-site workers.
