About Transformers Switchgear SF6 Protection Systems Cable Jointing Substations SAP (Senior Authorised Persons)
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From small, one-off installations to turnkey projects, we offer full project design services, project management and installation of transformers, protection systems, switchgear, substations, SF6 and cable jointing.

As well as keeping fully up to date with technological developments in high voltage equipment, our engineers receive extensive ongoing training. This enables Hornbill to assign a fully qualified project manager for the duration of your contract.

High Voltage – Part of Hornbill's full range of electrical engineering services.


Hornbill are highly experienced and knowledgeable in all aspects of transformer construction. Installation, testing and maintenance. From single small distribution transformers to multiple large power transformers.

Our experienced fitting and commissioning teams will provide you with first class service throughout the entirety of your transformer project. Our commissioning and testing engineers can carrying out a full sweep of finger print tests using the most up to date testing equipment.

The types of testing includes:

  • Tan Delta (Power Factor and Capacitance)
  • Sweep Frequency Response Analysis (SFRA)
  • Dielectric frequency Response (DFR)
  • DC Winding Resistance
  • Turns Ratio and Magnetising Currents

Our teams are also highly knowledge able and experience in carrying out full condition assessments for transformer repairs and refurbishments. This can be carried out on site or at our custom built transformer workshop where we can carry out all types of repairs including winding replacements.

To find out more about Hornbill’s Transformer services, call us on +44 (0) 1792 818111 or send us a message below.


Hornbill provides a full installation, testing and repair service for high voltage and low voltage switchgear.

To complement our MCC and control panel design and manufacturing capabilities our engineers have an extensive knowledge and experience across all types of old and new circuit breakers up to 400KV, including oil, SF6, air and vacuum breakers.

Hornbill Hornbill’s high voltage engineers work with all clients across the UK both on the transmission, distribution and private sectors to give planned or emergency assistance on a variety or switchgear and protection systems.

Our teams of switchgear engineers are on call 24 hours and days 365 days per year, we are fully aware of the sensitive nature of HV equipment and how much impact the loss of power has for our clients.

To discuss your high voltage and low voltage switchgear needs, call us on +44 (0) 1792 818111 or send us a message below.


Thanks to its excellent insulation properties, SF6 gas is increasingly used in high voltage switchgear, circuit breakers and other electrical equipment.

Decomposed SF6, however, contains toxic and corrosive gaseous and solid decomposition products. As a fluorinated gas, just 1 kg of SF6 equates to 22,200kg of CO2, posing a significant threat to air quality.

In many cases we can reclaim decomposed SF6 gas to make it reusable, using processes that comply fully with British Standards IEC 60480 and IEC 60376.

At Hornbill, we understand how to harness the significant technical advantages of SF6 while adhering to environmental regulations and minimising the potential environmental impact of this potent gas. Our high voltage maintenance teams are fully trained to manage SF6 gas in the working environment and exercise the utmost care when handling, processing and monitoring the gas.

Using specialist test equipment to assess, evacuate and charge high voltage equipment, Hornbill's engineers will ensure that your SF6 gas installations comply fully with all engineering and environmental requirements.

We also maintain close links with gas suppliers and reprocessing companies. This means we can provide full support for all your high voltage equipment that contains SF6 gas.

To find out more about Hornbill’s SF6 services, call us on +44 (0) 1792 818111 or send us a message below.

Protection Systems

When you choose Hornbill as your high voltage services provider, you can rest assured that all aspects of your protection systems, from design, installation and testing, are in safe, expert hands.

As part of our thorough site commissioning procedure, experienced and highly trained engineers at Hornbill will subject your protection systems to rigorous testing. This includes secondary and primary injection testing, annual relay trip testing and fault diagnosis.

Hornbill’s protection and commissioning engineers are highly experienced and trained in all manufactures of protection relays and systems. We use the most up to date technology in test equipment we provide a comprehensive completion testing report. Hornbill are fully equipped to carry out testing of all types of protection systems from old electromechanical relays right up to new state of the art electronic multi-processor systems.

Hornbill are fully aware of the sensitive nature of High Voltage equipment and the impacts any loss of power has for our client sites. Therefore we offer a 24/7 365 day a year call out arrangement if required.

To find out more about Hornbill’s Protection Systems service, call us on +44 (0) 1792 818111 or send us a message below.

Cable Jointing

Hornbill’s Jointing Technicians are experienced and highly competent in single and multi-core cable jointing. This includes all manufactures of cable joints and terminations used within the UK transmission and distribution networks.

We are authorised in all DNO’s within the UK and have a wealth of knowledge on all jointing techniques required. Our engineers are regularly verified for their skills under the Lloyds accreditation scheme and have experience in manufactures like:

Lovink and many more.

As well as this, we can take your old pitch link boxes and convert them to air boxes or replace the pitch with Guroflex. Guroflex Oil is a compound suitable for high voltage switchgear and transformer cable box filling. Guroflex is an excellent alternative to hazardous compounds like hot pour bitumen or G38. Guroflex can be used for 11KV and 33KV systems.

We can also offer:
• The supply of cable installation teams
• Various Cable Installation packages
• Testing at DC and VLF

Our teams of Jointers are on call 24 hours and days 365 days per year.

To find out more about Hornbill’s Cable Jointing services, call us on +44 (0) 1792 818111 or send us a message below.


Hornbill's substation installation, test and repair services cover a wide range of high voltage equipment, including open busbar earth switches, surge arrestors and circuit breakers.

To find out more about Hornbill’s Substations services, call us on +44 (0) 1792 818111 or send us a message below.

SAP (Senior Authorised Persons)

Hornbill can provide fully experienced & qualified SAP (Senior Authorised Person) personnel upto 33kv to operate & control your High Voltage distribution system.

Our SAP's are familiar with and can operate all types of high voltage switchgear, in order to isolate and prove the system is dead and therefor safe to be worked on. They can also carry out High Voltage fault testing & analysis and train others on site to Appointed Persons (AP), working with the client to ensure suitable provisions are in place for safe work to High Voltage distribution systems.

To find out more about Hornbill’s SAP services, call us on +44 (0) 1792 818111 or send us a message below.

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