What do an AP and a SAP actually do?
High voltage work in the UK is controlled through a set of safety rules and safety documents. Each person in that system holds a defined role. The Energy Networks Association's Model Distribution Safety Rules (ENA SHE Standard 07, Issue 3) cover the distribution companies. Under them, an Authorised Person is an experienced Competent Person with written authority for set duties, such as issuing and cancelling Limitations-of-Access or receiving Sanctions-for-Test.
A Senior Authorised Person is an Authorised Person who can also issue and cancel safety documents. Under the model rules, a Permit-to-Work has to come from a SAP before anyone works on apparatus. The SAP also marks out the work area in a substation where live HV conductors are exposed, and personally supervises certain earthing jobs. On National Grid's transmission system the duties are split into grades. SAP1 covers HV equipment, SAP2 covers LV equipment and SAP3 covers mechanical equipment, and an AP does switching on instructions from a Control Person.
How is an Authorised Person different from a Competent Person?
The model rules define a Competent Person as someone the company recognises as knowing enough, and having enough experience, to avoid danger. A Competent Person can be nominated to receive and clear certain safety documents, and must also be appointed in writing. The Competent Person is the first rung, and most jointers, fitters and electricians on an HV site start there.
An Authorised Person has more authority. They control access to equipment and take part in switching and testing. A SAP prepares and issues the permits that make the equipment safe for everyone else. Each step up means more responsibility for other people's safety, so each one has its own assessment.
Training, assessment and staying authorised
The law behind all this is the Electricity at Work Regulations 1989. HSE says anyone working on electrical systems must be competent for the task. That competence comes from training suited to the work, experience of doing similar work to a good standard, and regular reassessment. Anyone who can't show competence should only work under supervision from someone who can.
Employers set out the detail in their own procedures. At National Grid Electricity Transmission, SAP appointment depends on reaching a set level of competency and passing a formal company assessment. The AP route there includes a nominated mentor, an e-learning assessment watched by a trainer, and a final interview. Authorisation lasts three years. To keep AP authorisation, you're expected to carry out more than 12 switching instructions in the first year and have them signed off at your annual review.
How electricians move into HV
Most people come up through an electrical apprenticeship and then get onto HV sites as a Competent Person. That might be with a network operator, a contractor, an industrial site or a data centre. You build up switching and isolation experience under supervision, then your employer puts you forward for AP training and assessment. Offshore, OPITO has a High Voltage training certificate aimed at future Authorised Persons and HV engineers. Its entry requirement is a suitable apprenticeship, ideally electrical, or equivalent study plus workplace experience.
Your authorisation only covers your employer's rules and the systems named in your appointment. If you change employer, expect to be assessed and appointed again under their rules before you can issue a single permit.
Pay
GBP a year, before tax. These ranges run from the 25th to the 75th percentile, with UK medians around £64,700. They come from the ONS Annual Survey of Hours and Earnings, April 2026 (provisional), brought up to date with a wage index. The regional figures are modelled. Pay goes up with SAP status, standby and call-out, shift work and the voltage level you're authorised for. Refer to the High Voltage salary guide for figures from live adverts.
What you need
- Electrical backgroundExpect to need a completed electrical apprenticeship or equivalent. For example, OPITO's HV certificate asks for a suitable apprenticeship, ideally electrical, or equivalent study and workplace experience.
- Competent Person status firstUnder the ENA model rules, an Authorised Person has to be an experienced Competent Person with suitable technical knowledge and ability.
- Written appointmentCompetent Persons, APs and SAPs are all appointed in writing by the company, which spells out the duties and systems they cover.
- Formal assessmentEmployers such as National Grid Electricity Transmission appoint SAPs only after you reach a set competency level and pass a formal assessment.
- Ongoing practiceHSE expects regular reassessment. National Grid's AP route, for example, asks for more than 12 ratified switching instructions in the first year.
How to get there
- FirstQualify as an electricianFinish an electrical apprenticeship or an equivalent route with workplace experience.
- NextJoin an HV employerGet work with a network operator, HV contractor, industrial site or offshore operator where HV safety rules apply.
- Early yearsGet appointed as a Competent PersonReceive and clear safety documents and build up HV experience under supervision.
- When nominatedTrain and get assessed for APDo your employer's AP training with a mentor, then sit an assessment and interview.
- After appointmentTake on AP dutiesCarry out switching and access control, keeping records your manager reviews.
- With experienceProgress to SAPPass the SAP assessment so you can prepare and issue Permits-to-Work and other safety documents.
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Questions people ask
Can I take a course and become an HV Authorised Person straight away?
No. A course can give you training and a certificate, but only an employer can make you an Authorised Person, by appointing you in writing under its own safety rules. You'll normally need experience on its systems first.
What counts as high voltage?
The ENA model rules use the definitions in the Electricity Safety, Quality and Continuity Regulations 2002. High voltage is anything over 1,000 V AC or 1,500 V DC. Anything at or below that is low voltage.
Who issues a Permit-to-Work on HV equipment?
Under the ENA Model Distribution Safety Rules, a Senior Authorised Person issues the Permit-to-Work before any work starts on apparatus or conductors. An Authorised Person can issue Limitations-of-Access and receive Sanctions-for-Test.
Does my authorisation carry over if I change jobs?
No. An appointment covers the duties and systems named by the company that made it. A new employer will assess you against its own rules before it appoints you.
How long does authorisation last?
That depends on the employer. At National Grid Electricity Transmission, authorisation lasts three years and is kept up through refresher training, annual reviews and switching experience.
Sources
- Energy Networks Association: Model Distribution Safety Rules, SHE Standard 07 Issue 3
- National Grid Electricity Transmission: NSI 30 authorisation guidance, Issue 11
- National Grid Electricity Transmission: NSI 30 guidance, Issue 2 (role grades)
- National Grid Electricity Transmission: Safety Rules, Fifth Edition
- HSE: Work on electrical equipment, machinery or installations
- OPITO: Training Certificate, High Voltage
- HSE: Guidance on permit-to-work systems (HSG250)
