Every year, thousands of underground utility strikes occur across the UK. The cost runs into hundreds of millions of pounds when you factor in emergency repairs, project delays, compensation claims, and HSE enforcement actions. The human cost is harder to quantify: injuries, fatalities, and the psychological impact on operatives who strike a live service.
What is less widely discussed is where in the process these strikes happen. Industry data consistently shows that the overwhelming majority of incidents trace back to failures that occur before the excavation begins, specifically during the pre-dig survey phase. In practical terms, this means the first 20 metres of a cable route scan, the first few sweeps of a locator, and the first decisions an operative makes about what signals mean.
The Four Behaviours That Lead to Strikes
After delivering thousands of cable avoidance courses and carrying out on-site competency assessments, Sygma's trainers see the same four patterns repeated across every sector, every contractor, and every region.
1. Passive-Only Surveying
The single most common failure is an operative who scans in Power mode and Radio mode, decides the area is clear, and begins excavation without ever connecting a Genny. Passive detection picks up signals that are already present on buried services, but not all services carry detectable passive signals. A telecoms duct, a gas main, or a water pipe will often produce no response in passive modes at all. Without applying a known signal using a Genny, these services remain invisible. This is not a theoretical risk. It is the cause of a significant proportion of all utility strikes in the UK.
2. Inadequate Genny Application
Some operatives do connect the Genny, but only use Induction mode because it is the quickest and easiest method. Induction applies a signal to the general area rather than to a specific service. The signal can couple onto adjacent services, producing misleading readings and giving a false sense of security. Direct Connection, Clamp, and Capacitance are all more targeted methods that produce significantly more reliable results, but they require more knowledge and take more time. If an operative has only been trained to use Induction, they are missing the methods that matter most.
3. Misreading or Ignoring Signals
A locator produces numerical readings, graphical displays, and audio tones. Interpreting these correctly requires an understanding of signal behaviour, depth estimation limitations, and the difference between a peak and a null response. When operatives are not trained to interpret what the locator is telling them, they either miss services entirely or mark them in the wrong position. A service that is 30 centimetres from where it was marked is a strike waiting to happen.
4. Not Consulting Plans
Utility plans are not perfect. They are often out of date, lack positional accuracy, and may not show every service present. But they remain a critical starting point. An operative who does not consult asset owner plans before scanning is working blind. They do not know what to expect, cannot cross-reference their locator readings against known infrastructure, and cannot identify services that should be present but are not producing a response. Plans alone do not prevent strikes, but skipping them removes an important safety layer.
What Training Does to Address These Failures
The purpose of cable avoidance training is not just to show someone how to turn on a locator. It is to build the decision-making framework that prevents each of these four failure modes. A well-structured course should cover all four locating modes (Power, Radio, Genny, and Avoidance), all Genny signal application methods (Direct Connection, Clamp, Capacitance, Induction, and Nulling Out), signal interpretation and depth estimation, and the role of plans in the survey process.
This is why Sygma's approach centres on what we call the Genny-First methodology. Rather than treating the Genny as an optional extra that gets used if there is time, our training positions it as the default starting point. Operatives learn to apply a known signal first, locate it, and then use passive modes to identify additional services. This reversal of the typical workflow catches the services that passive-only surveying misses.
The data from organisations that have adopted this approach is consistent: Genny usage rates increase by 70 to 80% after training, and the number of services identified before excavation rises correspondingly.
Not All Training Delivers the Same Standard
A half-day refresher that covers the basics of Power and Radio mode, with a brief demonstration of the Genny, does not address the behaviours described above. Preventing utility strikes requires hands-on practice with all four modes, all Genny application methods, realistic signal interpretation exercises, and an assessment that tests whether the operative can apply what they have learned.
If you are responsible for operatives who carry out pre-excavation surveys, the question to ask your training provider is not whether they cover the CAT and Genny. It is whether they cover all four modes, all Genny application methods, and whether they assess competence across each one. That is the difference between a course that ticks a box and one that reduces your strike rate.