Overhead power lines near construction sites are one of the higher-consequence hazards on scaffold design. HSG144 sets out the HSE guidance for work near overhead lines, and the specific clearance distances and control measures it requires directly shape what scaffold can be erected safely, where the material can be lifted, and how the site logistics have to operate.
HSG144, clearance distances and the control measures required
The core requirement in HSG144 is establishing safe clearance distances from the live lines. The distances depend on the voltage class of the lines: minor voltages (below 1kV), medium (1 to 33kV), and high or extra-high voltage (above 33kV). Each has its own clearance envelope that scaffold and lifting operations must respect throughout the works.
Where the required clearance cannot be maintained by design, additional control measures are needed. Isolation and earthing of the lines during the works, arranged with the network operator, is one option. Insulating barriers or covers on the lines is another. Diversion of the lines is a third and typically the most expensive. Each requires early engagement with the network operator, often months of lead time.
For scaffold contractors, the practical implication is that scaffold design near overhead lines cannot be finalised without confirmed clearance data. The scaffold layout, height and access sequence all depend on knowing where the lines are and what voltage they carry. Assumptions produce designs that cannot be safely erected.
Programme and lift-plan implications on live sites
Globe Cambridge's engagement with principal contractors on sites near overhead power lines includes early identification of the constraint at pre-construction stage. Where the lines are visible on the site plan, we raise the HSG144 conversation before designing scaffold. Where the lines are not obvious, we require confirmation from the site survey team before scaffold design proceeds.
There is a specific operational issue around loading and unloading scaffold materials on sites with overhead lines. Cranes, forklift trucks and telehandlers all reach into the vertical envelope where lines may be. The lifting operations under LOLER need to include the overhead line constraints in the lift plan, not just the scaffold erection sequence.
The programme implications of overhead line constraints are often underestimated at cost plan stage. Network operator engagement for isolation, earthing or diversion typically takes weeks to arrange and requires scheduled outages. The scheme programme has to accommodate these outages rather than assume they can be arranged on demand.
How tender pricing should reflect overhead-line exposure
Where the works are close to but not directly under overhead lines, the constraint is often about people and equipment moving beneath the lines rather than the scaffold itself. Delivery vehicles, operatives with long tools, banksmen managing lifts. Each is a moving element that has to respect the clearance envelope. Site inductions need to cover the specific hazard.
For principal contractors evaluating scaffold tenders on sites with overhead line exposure, the specific question is whether the contractor's design has considered HSG144 explicitly. A generic scaffold price without HSG144 review is priced for a lower-risk site. On a site with real overhead line exposure, the generic price does not cover the necessary controls.
For developers and QSs pricing schemes near existing overhead infrastructure, the HSG144 conversation should happen at design stage rather than at scaffold procurement. A design that respects the constraints from the start is significantly cheaper to deliver than a design that requires network operator coordination retrospectively.
Talk to Globe Cambridge
To discuss scaffold design near overhead power lines on your scheme, contact Globe Cambridge on 01223 890727 or email enquiries@theglobegroup.co.uk.
