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This the 6th article, in my series of articles, describing what could be included in your Electrical Safety Management System. Electrical Safety UK has a model Electrical Safety Management System (ESMS) which includes an Electrical Safety Policy, Electrical Safety Rules and over 30 supporting instructions specific to different aspects of electrical safety. We can use this model system when developing with our clients a bespoke new ESMS or a review of their existing ESMS.
This article looks at the subject of breaking ground and the associated electrical risks. You need to comply with statutory regulations, ensuring safe working practices when breaking ground and excavating near buried electrical services. When breaking ground there is a risk of coming into contact with buried electrical cables, which may expose workers to electric shock and arc flash hazards.
Scope
You should have an instruction in your Electrical Safety Management System that addresses the electrical risks when breaking ground. That instruction should provide requirements and guidance on good practice that should be implemented to mitigate the risk. Your instruction should cover all electrical circuits, including high voltage and low voltage transmission and distribution systems, control circuits, and final circuits to equipment and services. Your instruction should outline the requirements and expectations for employees and appointed contractors working on electrical installations. It should also apply to third parties working on these systems where a “Transfer of Control” has not been established.
Responsibilities
Responsibilities extend beyond those directly involved in the operation and maintenance of electrical systems. Individuals involved in the design, planning, management, and implementation of projects affecting electrical services should comply with your instruction.
Procedure
While the instruction should focus on electrical services, it should also consider other underground services that may be disturbed. Works involving breaking ground include street works, roadworks, excavation, drilling, piling, demolition, site remediation, and investigation surveys. All excavation works should be planned and coordinated to minimize the risk of striking buried electrical services. Safe systems of work should be used to minimize damage to exposed services.
Identifying and Managing Dangers
Assume underground services exist and implement necessary control measures to avoid danger. Injuries can result from arcing current, fires, or electric shocks caused by live cables being penetrated or crushed. Incidents may also arise from disturbed or damaged cables left unreported. Consider the effects on other buried services, such as gas or mechanical pipes, and the risks posed by cable ducting. Follow the Confined Spaces Regulations 1997 when working in confined excavations.
Planning the Work
Identify the work area and locate underground services before starting. Obtain service drawings from utilities and consult existing site layout drawings. Conduct a physical survey to identify services and underground structures. Use appropriate survey equipment and methods, such as trial holes. Plan the work to avoid disturbing services and allow sufficient time and resources for safe execution. Emergency work still requires planning and assessment.
Detecting, Identifying, and Managing Underground Services
Use correct equipment and competent personnel to detect, identify, and mark underground services. Conduct desktop and site investigations to identify service locations. Communicate findings to the responsible person managing the works. Use detecting devices or locators, such as noise/sound detectors, radio frequency detectors, and ground probing radar. Mark services with biodegradable paint or waterproof crayon/chalk for short duration works.
Safe Excavation
Choose appropriate methods and techniques for safe excavation. Consider the nature of the work, underground services, ground conditions, and site constraints. Prepare a written plan (RAMS) and issue it to the work party. Ensure the work party is competent and equipped with suitable tools and PPE. Protect against excavation collapse and consider confined spaces implications. Supervise the works and avoid using electrical services as handholds or supports.
Restoration
Use materials free from aggregates and particles that may damage cables during restoration. Ensure the trench base is smooth and free from sharp objects. Line the trench with sand and encase the cable with a minimum of 100mm of sand. Backfill the trench with soil free of damaging particles. Follow the specified minimum cable depths for different ground types and install approved cable marker tapes and protection tiles.
By adhering to your instruction, you will ensure the safety of employees, contractors, and third parties when working near buried electrical services. Safety is a shared responsibility, and following your guidelines helps prevent accidents and ensures a safe working environment for all.
Electrical Safety UK can help you write such an instruction; we have model instructions that can be customised to meet your bespoke requirements by working with one of our Chartered Principal Engineers.
