HV & LV electrical engineering · Since 1966
We maintain, install, test and repair the high- and low-voltage networks that water works, data centres, defence sites and landmark London buildings can’t afford to lose. Planned around your operation, delivered safely, and backed by Senior Authorised Engineers on call 24/7/365.
Trusted on the networks behind
What we do
From the 33kV cable in the ground to the protection relay in the panel, we build, maintain and operate every part of your high- and low-voltage system. ABB, Schneider and every other make, modern or legacy.
01Build
New substations, switchgear, transformers and cabling: surveyed, designed, installed and commissioned by our own Projects and Civils teams. We’ll act as principal contractor under CDM when you need one.
02Maintain
Intrusive and non-intrusive maintenance to manufacturers’ recommendations or better, with partial discharge, thermographic and oil analysis to catch failing insulation before it fails.
03Operate & respond
Senior Authorised Persons to run your switching safely, operation and maintenance contracts that take the network off your hands, and one emergency number that’s answered day and night.
Projects
Water works that never stop. Trading floors. A defence range. Data halls in Iceland. This is what zero drama looks like on site.
Two shift teams worked around the clock to maintain around 80 circuit breakers and test every protection relay at the bank’s European headquarters, signed off long before the traders returned.
10km of cable, new substations, switchgear and transformers, delivered to schedule and saving the client over 20% of project costs.
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LV and HV switchgear tested and maintained in phased isolations, with no downtime or service interruptions reported by customers.
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12-yearly HV/LV inspection and testing under a Thames Water framework: 17 transformers across 9 locations, planned around a site that runs 24/7.
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Civil, earthing and electrical design, supply, installation and energisation, with both transformer bases raised a metre above ground.
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Transformer oil replaced after a failed sample, with planned HV/LV maintenance done in the same outage. No temporary generator needed. Zero incidents.
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A water-damaged LV switchboard: temporary generation and distribution installed the same day, then a new 3,200A board installed, graded and commissioned.
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HV testing and the replacement of multiple 11kV/400V transformers and feeder cables, planned around a department store’s trading hours.
Read the case studyOn call now · 24/7/365
One number, day or night, every day of the year. A Senior Authorised Engineer is on site within 2–4 hours to make it safe, find the fault and get you back on supply wherever possible. Then we mobilise the jointers, kit and temporary power to put it right.
Emergency line · 24/7/36501245 266800One number, answered 24/7. Tell us the site, what’s failed and who’s there.
A Senior Authorised Engineer on site within 2–4 hours.
Isolate, locate the fault and restore supply where it’s safe to, including temporary generation.
Cable fault location, excavation, jointing, testing and neat reinstatement.
“Thank you for your team’s efforts over the weekend (where you saved their bacon), much appreciated.”
“It was a great response time and was welcomed by the ISS team.”
The cost of “it’ll be fine”
Planned maintenance happens on your schedule. Faults happen on theirs. Try your own numbers.
At Warburtons in Enfield we combined a transformer oil replacement with planned HV and LV maintenance in a single outage, and had the bakery back on supply before midday.
Platinum accredited employer, 2025
Why Power Testing
Since 1966 we’ve grown the way good engineers work: carefully. Around 60 people, many with decades of service, some the second generation of their family to work here. In 2025 we became part of MARCH: the same people, standards and phone numbers, now backed by the wider resources of a multidisciplinary engineering group.
Our Speak Up policy means anyone can raise a safety concern, on any job, without fear of repercussions. ISO 45001 certified, RoSPA Gold 2023, and every one of us First Aid trained, including for electric shock, burns and flashover.
Over a dozen of our people have more than 20 years’ service, and our Projects Director started here as an apprentice. You get the same faces, who know your site.
ABB, Schneider and every other manufacturer, modern and legacy. We hold spares in our own warehouse and train on real switchgear and relays in our Chelmsford workshop.
Every contract has a dedicated client team, from site survey to O&M manuals, and a single point of contact when it matters most.
“PT as a company is Power Testing, but it could also stand for Professionally Trained, Personal Touches or Preferred Team.”
“A terrific job by all, everything completed with minimum worry, as per PTL’s standard.”
“I would be happy and ready to recommend their electrical services to any other organisation.”
“Power Testing demonstrated exceptional professionalism and technical competence… reinforcing confidence in the reliability and safety of our systems.”
“This is a clear understanding of what a service partnership should be.”
“Excellent team, professional attitude and the project went perfectly. Power Testing are now our preferred contractor for upcoming projects.”
“The lads have gone over and above what normally might be expected… They are truly great ambassadors for your company.”
“Andy Fitzgerald owned the project from start to finish and made an exceptional effort to ensure this complex project was a success.”
How we work
Step 01
We review your schematics and asset list, walk the site and agree exactly what’s in scope.
Scope agreed
Step 02
Switching schedules, RAMS and permits ready before we arrive, with outages planned around you: nights, weekends, bank holidays.
Outage planned
Step 03
Authorised switching, then maintenance and testing to manufacturers’ recommendations or better, by trained and assessed engineers.
Tested
Step 04
A signed Work Completion Form on the day, then full test records, defects and recommendations, so you know exactly where your network stands.
Signed off
Accreditations
Utilities, defence, FM and construction frameworks ask for proof. Here’s ours, and we’ll send the certificates for your supplier onboarding.
NICEICApproved for installation & testing to BS 7671
Lloyd’s RegisterNational Electricity Registration Scheme (NERS)
ATLASQualified contractor member
ISO 9001:2015Quality management, certified since 1995
ISO 14001:2015Environmental management
ISO 45001:2018Occupational health & safety
RoSPA Gold Award2023
Cyber EssentialsCertified
Environment AgencyUpper-tier waste carrier & dealer
Achilles UVDBUtilities Vendor Database
Achilles Building ConfidenceAccredited
ConstructionlineGold member
CHASAccredited contractor
SafeContractorAccredited (Alcumus)
CIRASConfidential reporting memberBest EmployersEastern Region, Platinum 2025–27
Armed Forces CovenantSignatory
ICORegistered data controllerOnboarding us as a supplier? We’ll send our certificates and policies in one pack.
Request the accreditation packGet a quote
Three quick steps. Our estimating team reviews every scope and comes back with sensible questions or a clear, no-obligation quote.
Your scope
FAQs
The questions facilities managers, engineers and procurement teams ask us most.
Something else? Call 01245 266800 or email info@powertesting.co.uk.
Both LV and HV. We maintain, test and commission high- and low-voltage networks and switchgear, and our cable jointers work on everything from paper-lead to modern polymeric cables, up to and including 33kV.
Yes. We maintain ABB, Schneider and every other manufacturer’s HV and LV equipment, modern and legacy. We keep spares in our own warehouse and source parts for old and new equipment through our industry contacts.
Our emergency line is answered 24 hours a day, 365 days a year, and a Senior Authorised Engineer will be on site within 2–4 hours to make safe, assess the fault and, wherever possible, restore supply. Call 01245 266800.
That’s how we prefer to work. We plan outages for nights, weekends and bank holidays, use phased isolations and temporary supplies where they’re needed, and agree every step with you beforehand. Morgan Stanley’s maintenance was done over an Easter weekend; Warburtons was back on supply before midday.
Yes. Our Senior Authorised Persons carry out switching and safety duties under our DNO-orientated Electrical Safety Rules or your own approved rules, from ad hoc visits and out-of-hours callouts to a full-time site presence. We also offer SAP training for your own staff.
Yes. We deliver turnkey projects as principal contractor under CDM, from civils, design and supply through installation, commissioning and O&M manuals.
NICEIC, Lloyd’s Register NERS, ISO 9001 (since 1995), ISO 14001 and ISO 45001, Achilles UVDB and Building Confidence, Constructionline Gold, CHAS, SafeContractor and Cyber Essentials, among others. See them all, or ask and we’ll send the certificates.
Across the UK from our head office in Chelmsford and our office in Manchester, and overseas when clients need us, as at Verne’s data centre in Iceland.
Day to day, nothing you’ll notice: the same people, standards and phone numbers. Behind them, we now have the wider resources of MARCH, a multidisciplinary engineering provider.
Yes. As an NICEIC approved contractor we carry out fixed wire inspection and testing to BS 7671, which helps duty holders show compliance with the Electricity at Work Regulations 1989, and we can complete small installations and remedial work too.
Talk to engineers who’ve been doing this for 60 years.
Head office, Chelmsford
33 Hanbury Road, Widford Industrial EstateManchester office
Unit 7, Mayfield Industrial Estate
