CAT and Genny equipment is an important part of planning and carrying out excavation work safely. However, it doesn\u2019t guarantee that all underground services will be found, so it should always be used alongside utility plans, a suitable site survey and safe digging practices.<\/p>\n\n\n
![\"Construction](\"https:\/\/www.highspeedtraining.co.uk\/hub\/wp-content\/uploads\/2026\/10\/construction-worker.jpg\")
<\/figure><\/div>\n\n\nA CAT detects electromagnetic signals from underground services. These signals may already be present, such as those associated with electrical power, or they may be deliberately applied using a Genny. The operator moves the CAT over the ground, following the manufacturer’s instructions and using the appropriate detection mode. Changes in the signal help indicate the likely position and route of a buried service.<\/p>\n\n\n\n
For the best results, operators need to understand the functions of both devices, and their limitations.<\/p>\n\n\n\n
How Does a CAT Work?<\/h4>\n\n\n\n
A CAT is designed to detect electromagnetic signals that can indicate the presence of buried cables or services. Different models offer different detection modes, which may include power, radio and Genny signals. The main functions of a CAT include:<\/p>\n\n\n\n
- \n
- Power mode<\/strong> \u2013 detects electromagnetic signals associated with electrical power cables. However, not all cables produce a detectable signal, particularly if they are not carrying a suitable load.<\/li>\n\n\n\n
- Radio mode<\/strong> \u2013 detects certain radio signals that can be picked up by buried conductive services, helping operators trace their routes.<\/li>\n\n\n\n
- Genny mode<\/strong> \u2013 detects the specific signal transmitted by a compatible Genny, helping operators locate and trace services that might otherwise be difficult to detect.<\/li>\n<\/ul>\n\n\n\n\n\n
Some CAT models operate manually, allowing the user to select the detection mode and adjust sensitivity. Others offer automatic functions that help manage sensitivity or reduce the chance of missing a signal.<\/p>\n\n\n\n
A CAT can indicate the approximate position of a service, but note that the reading can be affected by the type and depth of the service, surrounding conditions and the operator’s technique. Therefore, a CAT shouldn\u2019t be relied on as the only method of locating underground utilities.<\/strong><\/p>\n\n\n\n
How Does a Genny Work?<\/h4>\n\n\n\n
A Genny generates an electromagnetic signal that a compatible CAT can detect. This helps the operator trace a buried service more reliably, particularly when the service doesn\u2019t produce a strong signal naturally. Depending on the equipment and the type of service, the signal can be applied in different ways:<\/p>\n\n\n\n
- \n
- Induction <\/strong>\u2013 the Genny is placed above the suspected route of a buried service and transmits a signal that can induce a current in suitable conductive services below ground.<\/li>\n\n\n\n
- Direct connection <\/strong>\u2013 a compatible connection lead is attached to an accessible part of the service (where safe and permitted to do so). This applies the signal more directly and can help improve detection.<\/li>\n<\/ul>\n\n\n\n\n\n
Direct connection must only be carried out by someone competent to do so, following the equipment manufacturer’s instructions and the relevant safety procedures. Electrical services must never be accessed or connected to without appropriate authorisation and precautions.<\/p>\n\n\n\n
Once the signal has been applied, the operator uses the CAT in the matching detection mode to trace the service. Correct positioning, settings and technique are essential for obtaining reliable results.<\/p>\n\n\n\n
\n\n\n\nCAT and Genny Questions and Answers<\/h2>\n\n\n\n
Below are 10 common questions about using, checking and maintaining CAT and Genny equipment. Note that operators should always follow the manufacturer’s instructions and the Health and Safety Executive’s (HSE) guidance<\/a> on avoiding danger from underground services.<\/p>\n\n\n\n
Q: Can you use a CAT without a Genny?<\/strong><\/p>\n\n\n\n
A: <\/strong>Yes, a CAT can detect naturally occurring electromagnetic signals in Power and Radio modes without a Genny. However, these signals aren\u2019t always present or strong enough to detect. Using a Genny can help identify and trace suitable services more reliably.<\/p>\n\n\n\n
Q: Can a CAT and Genny detect every underground service?<\/strong><\/p>\n\n\n\n
A: <\/strong>No, the equipment has limitations and cannot guarantee that every buried service will be found. Detection depends on factors such as the material, depth and condition of the service, the strength of the signal and nearby sources of interference. For example, plastic pipes without tracer wires generally can\u2019t be detected directly, so additional equipment, such as a sonde or traceable rod, may be needed to locate them.<\/p>\n\n\n\n
Q: Why is CAT and Genny calibration important?<\/strong><\/p>\n\n\n\n
A: <\/strong>Calibration helps confirm that the equipment is operating within the required tolerances and detecting signals, as expected. Faulty or poorly maintained equipment may give misleading readings or fail to detect services, increasing the risk of a strike. The HSE’s guidance<\/a> also recommends regular checks and calibration of locating equipment.<\/p>\n\n\n
\n![\"Calibration](\"https:\/\/www.highspeedtraining.co.uk\/hub\/wp-content\/uploads\/2026\/10\/calibration.jpg\")
<\/figure><\/div>\n\n\nQ: How often should a CAT and Genny be calibrated?<\/strong><\/p>\n\n\n\n
A:<\/strong> Many manufacturers recommend annual calibration, but the correct interval depends on the specific model and the manufacturer’s instructions. Employers may also set shorter intervals based on how frequently the equipment is used and the conditions in which it operates. Equipment may need checking or recalibrating sooner if it has been dropped, damaged, exposed to water or has started producing inconsistent readings.<\/p>\n\n\n\n
Q: What pre-use checks should you carry out on a CAT and Genny?<\/strong><\/p>\n\n\n\n
A: <\/strong>Before using the equipment, operators should complete checks to identify faults that could affect its performance. These typically include inspecting the CAT, Genny, leads and accessories for visible damage, checking the batteries, confirming that any self-test completes successfully, checking that the display, controls and audible signals work correctly, testing the equipment’s response against a known signal and confirming that it is within its required calibration or service period. If the equipment fails a check or appears faulty, do not rely on it to locate underground services until the problem has been resolved.<\/strong><\/p>\n\n\n\n
Q: Can weather or ground conditions affect CAT and Genny readings?<\/strong><\/p>\n\n\n\n
A:<\/strong> Yes, nearby metallic objects, other buried services, electrical interference and site conditions can affect signal detection and interpretation. The depth and material of a service can also influence whether it can be located. Operators should follow the manufacturer’s guidance, scan systematically and investigate unexpected or inconsistent readings rather than assuming the ground is clear.<\/p>\n\n\n\n
Q: Can a CAT and Genny tell you how deep an underground service is?<\/strong><\/p>\n\n\n\n
A: <\/strong>Some models can estimate the depth of a service when used with a suitable signal and the correct technique. However, depth readings are estimates and can be affected by signal distortion, nearby services and operator error. A depth reading should not be treated as an exact measurement or used on its own to determine whether excavation is safe.<\/p>\n\n\n
\n![\"Construction](\"https:\/\/www.highspeedtraining.co.uk\/hub\/wp-content\/uploads\/2026\/10\/digging.jpg\")
<\/figure><\/div>\n\n\nQ: Do you still need utility plans if you use a CAT and Genny?<\/strong><\/p>\n\n\n\n
A:<\/strong> Yes, utility plans provide important information about the services that may be present, while CAT and Genny equipment helps investigate their likely positions on site. Plans may be incomplete or inaccurate, and detection equipment also has limitations, so both should be used alongside visual inspections and appropriate safe digging methods.<\/p>\n\n\n\n
Q: Does using a CAT and Genny mean it is safe to dig?<\/strong><\/p>\n\n\n\n
A: <\/strong>No, the equipment helps locate services but doesn\u2019t guarantee that the ground is free from buried hazards. Services may be missed because they don\u2019t produce a detectable signal or because of the equipment’s limitations. Detected services should be clearly marked and excavation must follow the site’s safe system of work<\/a>.<\/p>\n\n\n\n
Q: Does someone need training to use a CAT and Genny?<\/strong><\/p>\n\n\n\n
A: <\/strong>Yes, anyone using the equipment should receive suitable CAT and Genny Training<\/a> and understand how to operate it correctly, interpret readings and recognise its limitations. Training should cover the relevant detection modes, pre-use checks, equipment maintenance and the steps to take when readings are unclear or unexpected. Refresher training may also be appropriate when equipment or working practices change.<\/p>\n\n\n\n
\n\n\n\nUnderstanding how to use and maintain CAT and Genny equipment is essential for anyone involved in excavation work. Regular checks, appropriate calibration and suitable training help ensure the equipment can be relied on to support safe working practices.<\/em><\/p>\n\n\n\n
\n\n\n\nFurther Resources:<\/h3>\n\n\n\n
- \n
- CAT & Genny Training<\/a><\/li>\n\n\n\n
- Toolbox Talks in Construction: Guidance on Meeting Topics and Resources<\/a><\/li>\n\n\n\n
- Grinding Safety Precautions and Control Measures<\/a><\/li>\n<\/ul>\n\n\n\n
<\/p>\n","protected":false},"excerpt":{"rendered":"
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- Direct connection <\/strong>\u2013 a compatible connection lead is attached to an accessible part of the service (where safe and permitted to do so). This applies the signal more directly and can help improve detection.<\/li>\n<\/ul>\n\n\n\n\n\n
- Radio mode<\/strong> \u2013 detects certain radio signals that can be picked up by buried conductive services, helping operators trace their routes.<\/li>\n\n\n\n