How is work near overhead power lines managed?

Contact with an overhead line is one of the small number of construction incidents that is routinely fatal, and it happens to plant operators doing ordinary tasks.

Which is why the controls are prescriptive rather than judgement based, and why the assessment happens before plant comes to site rather than when it arrives.

Establish the voltage first

The approach distance depends on the voltage, and the voltage cannot be judged by looking at the line.

So it is confirmed with the network operator. Low voltage distribution, high voltage distribution and transmission lines each carry a different exclusion distance, and the distance for a transmission line is substantially larger than most people assume.

The confirmation is in writing and it forms part of the assessment. Where the operator identifies the line as part of a larger network asset, the engagement with them runs alongside the work in [service location and utility relocations](/answers/service-location-and-utility-relocations).

The approach distances apply to more than the boom

The exclusion zone is around the conductor, in three dimensions, and the distance applies to anything that enters it.

**Plant,** including the boom, the jib, the bucket, the mast and any part that can be raised.

**The load,** which on a crane lift can swing well outside the plant footprint. Lift planning near lines has to account for the load path and for the possibility of a swing.

**Scaffolding and formwork,** as it is erected and as it is dismantled. The dismantling is when a panel is tipped and reaches higher than it ever did in service, which is the connection to [working at height on occupied buildings](/answers/working-at-height-on-occupied-buildings).

**Materials being handled by hand,** including lengths of pipe, reinforcement and sheeting carried upright.

**Water,** because a hose stream can conduct, which matters for dust suppression and concrete washdown.

**The line itself,** which moves. Conductors sag further in hot weather and sway in wind, so the clearance measured on a cool still morning is not the clearance on a hot windy afternoon.

The control options

In order of reliability.

**Avoid the zone entirely.** Reposition the work, the plant or the access so the exclusion zone is never approached. Always the first option considered.

**De-energise the line,** arranged with the network operator, with a scheduled outage. The most reliable control and the one with the longest lead time, because an outage affecting customers has to be planned and notified.

**Relocate or raise the line,** which is a network operator work order with design, approval and construction time attached. Appropriate where the conflict is permanent rather than for a single activity.

**Insulate the line,** with covers fitted by the operator, which reduces the approach distance without removing the hazard.

**Physical barriers and goal posts,** which stop plant physically entering the zone rather than relying on the operator noticing.

**A trained safety observer,** who watches the clearance continuously and does nothing else. The weakest of the controls because it relies on a person, and it is never the only control on a high voltage line.

Tiger tails, the visible markers on a line, are a warning device rather than insulation. They mark the hazard and they do not change the approach distance.

Where it comes up on a live site

The conflicts that recur on school and council projects are predictable.

**Crane and truck access at the site frontage,** where a low voltage service crosses the entry. The most common one, and the reason the delivery route is assessed before the first truck, per [traffic management and deliveries to a live site](/answers/traffic-management-and-deliveries-to-a-live-site).

**Roof work on a building with a service attached to it,** which brings the line within reach of the working platform. Relevant to [roof replacement on an occupied building](/answers/roof-replacement-on-an-occupied-building).

**Tree works** near a line, where the branch being removed is itself in the zone, which overlaps with [tree protection on construction sites](/answers/tree-protection-on-construction-sites).

**Excavators working with the arm raised** while travelling, which puts the boom tip higher than the operator is thinking about.

**Lighting pole and goal post installation** on a sports field crossed by a line, as in [sports field floodlighting](/answers/sports-field-floodlighting).

Documented and inducted

The assessment, the approach distances and the controls go into the site safety documentation and into every induction, with the location of each line marked on the site plan.

Which means every operator who comes to site knows where the lines are before they start, rather than finding out from a spotter, and it forms part of the process in [workforce screening and site inductions](/answers/workforce-screening-and-site-inductions).