Most cable strikes on UK construction sites are not caused by missing certificates or faulty equipment. They are caused by a small number of recurring habits, and they are entirely trainable.
Walk a few excavation sites, a pattern emerges. The strikes that happen rarely come down to a freak event or unmappable utility. They come down to a handful of behavioural shortcuts, repeated across thousands of digs, that quietly turn a routine excavation into an incident.
Peter Ashcroft, founder of cable avoidance specialist Sygma Solutions, has spent more than two decades training operatives across the UK utilities and construction sectors. The same four behaviours, he says, account for the vast majority of strikes Sygma is asked to investigate after the fact. None of them requires new equipment to fix. All of them require deliberate training and reinforcement.
1. Reaching for the CAT Without Connecting the Genny
This is the single most common shortcut on UK excavation sites. The Cable Avoidance Tool gets used in its passive Power or Radio modes. The operative walks the area, the sweep shows nothing alarming, and the dig begins. The Genny, the signal generator that gives the CAT genuine accuracy, stays in the van.
The problem is that passive sweeps miss services routinely. Unenergised cables and metallic services without strong re-radiated signals can sit invisible under a passive scan, and plastic mains can’t be detected by a CAT in any mode – with or without a Genny. Connecting the Genny applies a known signal to a target conductor, which transforms detection rates on the metallic services that a passive sweep would otherwise miss.
The fix is structural. Training that introduces the Genny first, before passive sweeping, changes the muscle memory operatives bring to the site. Sygma reports that clients who adopt this Genny-first approach see Genny use on live sites rise by 70 to 80 per cent, measured directly from locator data downloads.
2. Skipping Pre-use Equipment Checks
The CAT and Genny are precision detection equipment. A flat battery, a damaged signal clamp, or a unit drifting out of calibration will produce readings that look credible but are not. Pre-use functional checks take less than two minutes and confirm the equipment is doing what it is supposed to do.
The recurring pattern in incident investigations is that these checks were either skipped entirely or rushed to the point of being meaningless. The fix is to make pre-use testing a non-negotiable part of every dig, written into the method statement and enforced at toolbox talk level. Operatives need to be trained to treat a pre-use test the same way a driver treats a seatbelt: not optional, not occasional, every time.
3. WOrking From Outdated or Absent Utility Plans
HSG47 and the CDM Regulations require contractors to obtain utility plans before excavation begins. In practice, plans are often missing, partial, decades old, or never reconciled against what the CAT and Genny actually find on site.
The strike risk here is not abstract. Utility records in the UK are notoriously incomplete, and assuming a plan reflects reality is one of the more dangerous shortcuts an operative can take. Good training addresses this by teaching operatives to treat plans as a starting point rather than a conclusion, and to use the CAT and Genny to verify what the plan claims. Where plan and instrument disagree, the instrument wins.
4. Going Straight to the Mechanical Plant Without Trial Holes
The temptation, especially under programme pressure, is to bring in the excavator as soon as the sweep is complete. HSG47 is unambiguous that trial holes dug by hand should be used to verify the location and depth of services before the mechanical plant is brought to bear.
This is the behaviour that most directly causes the catastrophic strikes, the ones involving high-voltage cables or gas mains, where the consequences move from financial to fatal. Training that drills the trial-hole step as a fixed part of the procedure, rather than an optional safety check when there is time, is what separates sites that have strikes from sites that do not.
The Common Thread
What unites these four behaviours is that none of them is caused by ignorance. Operatives know they should connect the Genny. They know pre-use checks matter. They know plans are unreliable. They know trial holes are required. The behaviours persist because time pressure, habit, and the lack of on-site reinforcement between formal training cycles erode the discipline that good training originally instilled.
Pete Ahscroft is direct about what this means for site managers. “A certificate dated three years ago tells you the operative was trained. It tells you nothing about whether they are still applying that training today. The contractors who avoid strikes are the ones who check, on site, that the behaviour is still there.”
For construction businesses looking to reduce strike incidence, the route is not exotic. It is rigorous initial training, regular reinforcement, and competency evidence between certificate renewals. Further information on cable avoidance training is available from Sygma Solutions.
