Cable Avoidance Before You Drive or Dig — Scanning for Buried Services

Driving a stake into a buried cable or gas main is one of the few mistakes on an event site that can kill someone. Before you stake or dig where services might run, you check — and the standard tool for that check is a CAT and Genny. This guide covers why and when you scan, what the kit does, and the bit people forget: scanning informs safe digging, it never replaces it.

Why It Matters — and What the Rules Say

Event and marquee sites are full of reasons to put steel in the ground — stake lines, anchor points, ground bars. Estate, showground and heritage venues are also full of buried services that are often old, poorly documented, or unmarked. Put those two facts together and cable avoidance stops being paperwork and becomes the thing that keeps a crew alive.

It is also expected practice. MUTA's 2026 Best Practice Guide makes cable avoidance a formal requirement before ground penetration where underground services are unknown, and the HSE's HSG47, "Avoiding danger from underground services," sets out the approach the wider construction industry already works to: get the service drawings, scan with a cable locator, and dig safely. None of that is specific to marquees — but every one of those steps applies the moment you drive a stake into ground you do not fully know.

What a CAT and Genny Actually Does

A "CAT and Genny" is two tools that work as a pair. The CAT — Cable Avoidance Tool — is the detector: it picks up electromagnetic signals radiating from buried metallic services and turns them into an audible and visual response, so you can find and follow a line. The Genny — the signal generator — does the reverse: it applies a distinctive signal to a specific pipe or cable so the CAT can detect it, either by connecting directly to the service or by inducing a signal into it.

The detector has several modes, and they don't all find the same things — power mode reads loaded power cables, radio mode reads signals re-radiated by long metallic services, and the Genny mode reads the signal you have applied. The short version for this overview: a CAT used on its own, in its passive modes, will miss services that aren't radiating a detectable signal. That is exactly why you bring the Genny and why you don't treat a quiet detector as an all-clear. We cover the modes in what a CAT and Genny is, and how it works, and what a survey involves in how to survey with a CAT and Genny.

When You Need to Scan

The trigger is simple: any time you are about to break ground — drive a stake, drive an anchor, dig a footing — at a location where buried services could be present and you cannot rule them out from reliable drawings. In practice on event sites that means most ground near buildings, car parks, lighting columns, supply points, and anywhere with a service running to it.

Start before you arrive: ask the venue for service drawings. Treat them as a guide, not gospel — services move, get added, and are rarely as-built. On site, scan the staking area before you commit the layout, mark what you find, and keep clear of it. For a marquee specifically, that means sweeping the stake line and the high-load anchor positions, not just the centre of the footprint — our guide to scanning a marquee site before you stake walks through it step by step.

Locate, Then Dig Safely — the Whole System

A CAT and Genny is one part of a three-part system, and the parts only work together: plans, locate, dig safely. Drawings tell you what should be there; the scan tells you what you can detect on the day; and safe digging is how you confirm it without harm. Where you have to break ground next to a located or suspected service, expose it by hand-digging or vacuum excavation rather than driving or machine-digging blind.

This is the same discipline that underpins the rest of safe staking — drive vertical for holding power, yes, but only once you have established the ground is clear to drive into. See our guides on driving stakes with a powered breaker and staking in hard ground, both of which start from the same place: check what's underneath before the first blow.

What Scanning Won't Tell You

The honest part. A CAT and Genny reduces risk; it does not remove it. Power mode only finds loaded cables, so an unloaded or disconnected cable can sit silent. Radio-mode signals are not always present. And plastic or rubber pipes — increasingly common for water and gas — carry no signal at all unless one is applied, which is not always possible. A clear scan means "nothing detected with the methods used," not "the ground is empty."

So the right mindset is layered: use the drawings, scan in every mode, use the Genny, mark up carefully — and then still dig as if something is there. Treat the survey as the thing that tells you where to be most careful, not as permission to stop being careful.

Bringing Cable Avoidance Kit Into the Range

We're adding cable-avoidance equipment — a CAT and Genny — to the Hogan range, so the crews driving our stakes can scan the ground first with kit from a single supplier. If you'd like to know more, or talk through cable avoidance on a specific site or venue, get in touch.

No hard sell — just a straight conversation about what you're working with.

Email: hoganuk [at] hoganstakes.co.uk
Contact form: hoganstakes.co.uk/contact
Product range: hoganstakes.co.uk/products

Safety note — this is an overview, not training. Cable avoidance is safety-critical work. This guide explains why and when you scan; it is not a substitute for competent, trained use of a cable locator (see HSE HSG47) or for the venue's own service information and your risk assessment. If you are not confident a location is clear, do not break ground until it has been established safely.

Background drawn from HSE HSG47, the MUTA 2026 Best Practice Guide, and publicly available CAT & Genny training material (Paragon, Sygma Solutions, Proper DIY). Used as reference; adapted for UK event-site practice.