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High Voltage Inspections / Maintenance

Our Services List

What Electricity Supply Solutions can do for you.

High Voltage Inspections/Maintenance.

We provide preventive (eventually curative) actions to be performed on-site aiming to maintain the performance of transformers and switchgear.
As you may already be aware, anyone who is supplied high voltage electricity must by law, have appointed authorised person(s) to manage the equipment on site

These mandatory rules and regulations are laid out in the Health and Safety at Work Act 1974, The Management of at Work Act 1989. This is defined by the H.S.E as “person(s)who have full high voltage training, this being mandatory to ensure any / all electrical systems are maintained and operated in a safe condition". As stated in the Health & Safety at Work Act 1974, the requirement is to maintain electrical equipment in a safe condition. Part of the maintenance schedule should include periodic inspections and testing to monitor condition and efficiency.
ESS ltd are a high voltage installation / maintenance team specialising in contracts to support partners who have high voltage equipment. Whilst undertaking the role of onsite authorised person(s), if that customer does not have an employee(s) trained at high voltage.

We offer two types of contract to our partners:

The first is to control/maintain a customer's equipment, if they do not already have a trained high voltage person to operate their equipment.
The second being purely maintenance for customers who have their own trained authorised person(s).
Both types of contract apply for our 24/7 365 fault response.
Inspecting and maintained switchgear

You should regularly inspect, maintain and test all switchgear and its environment, for example the switch room. In all cases you should do this in accordance with the manufacturer’s instructions. Also, materials such as oil and sulphur hexafluoride have their own requirements for handling, cleaning, avoidance of contamination, disposal and recycling. There are also hazards associated with their use. ESS have a experience and knowhow to help you with all you High Voltage Inspection/Maintenance requirements.


You should inspect substations regularly. During the inspection work you should prioritise any remedial actions as follows:

Immediately (this should always be the case when security of the substation enclosure has been interfered with);
Earliest possible opportunity;
Next scheduled maintenance
ESS have an enhancive checklist of requirements as set out by the HSE to ensure you are up to current regulations and are aware of any changed that may be required.


You should do this at regular pre-determined intervals by, for example, time-based preventative maintenance - see below. You should also do it, particularly in the case of oil-filled circuit-breakers, immediately after it has operated to switch off an electrical fault in the network. Certain types of switchgear (such as that using sulphur hexafluoride and vacuum) are sometimes designated or described as ‘low maintenance’. However, you should not interpret this to mean that no maintenance is required. ESS engineers can help you determine what requirements best suit you

Time-based preventative maintenance This system of carrying out maintenance at regular, pre-determined intervals has been in use for many years. You decide the frequency of maintenance from factors such as:

The type of switchgear;
Whether it uses oil, sulphur hexafluoride or vacuum interrupters;
Its age and how often it is operated.
You should also take the maintenance history of the switchgear into account. You should keep records for each item so you can identify aspects such as deterioration in the condition of the equipment. You can then adjust the period between each maintenance accordingly. ESS can help you with all your High Voltage maintenance requirements.