What does planned HV maintenance actually involve?

Many site managers have maintenance done every year without really knowing what’s being checked or what the report is telling them. What happens on a maintenance visit, why does each part matter, and what should a site get out of it?

Why does planned maintenance matter?

Regular, planned HV (high-voltage) maintenance is important because it means that any problems can be spotted early. It keeps the site running, reduces the risk of equipment failure and unplanned outages, and allows defects to be identified and resolved sooner rather than later.

HV maintenance also means a site can meet its responsibilities. Using an authorised high-voltage contractor helps you meet your duties under the Health and Safety at Work Act 1974 and the Electricity at Work Regulations 1989.

HV maintenance is a legal requirement for duty holders, not optional.

What does a maintenance visit typically involve?

HV maintenance covers visual inspections, testing and repairs of HV electrical systems. It involves inspecting and testing the key equipment (transformers, switchgear, cables and protection) and checking its condition.

We can perform specific tests such as:

• Oil sampling (this can involve drawing a sample from a power transformer to test its health and prevent sudden failures).
• Partial discharge monitoring (provides early warning of insulation failure within high-voltage terminations)

We can also complete an intrusive maintenance visit, requiring a planned shutdown, to assess internal components.

What does the site need to do?

Your site needs to provide access, plan any shutdowns, and coordinate with the AP (authorised person) arrangement.

For a reminder of the services APs can provide, read our article: What does an Authorised Person arrangement involve?

What does a good maintenance report give you?

A good maintenance report shouldn’t just be a list of findings. It should show a clear priority, what needs doing and roughly when, so it helps with the next decision.

(Read our article: What happens after an issue is identified on an HV network?)

How might ESE help?

If you want a conversation about your current maintenance or a review of your last report, why not get in touch and we can talk it through with you. ESE provides both planned preventative maintenance (PPM) & reactive maintenance contracts to ensure your high voltage apparatus remains operationally safe, compliant and reliable.

We also offer 24/7, 365-day callout, and can act as an Authorised Person (AP) for some sites, effectively managing the legal safe operation of a HV network on your behalf.