High voltage electrical installations present concentrated fire and explosion risks. Arc flash events can release enormous energy in milliseconds.. HV Electrical Fire Risks High voltage electrical installations — switchgear, transformers, cables — present concentrated fire hazards with potential for catastrophic failure. Arc Flash Events An arc flash occurs when an electrical fault creates a sustained arc between conductors: Temperatures can reach 20,000°C (4x the surface temperature of the sun) Pressure wave of up to 2,000 lb/ft² — can blow walls down Molten copper and aluminium ejected at high velocity Event duration typically 0.1 2 seconds but consequences are devastating Arc flash incidents cause multiple fatalities annually worldwide Fire Protection for HV Switchrooms Detection: Arc flash detection systems (optical + overcurrent) — operate in <5ms VESDA aspirating detection for incipient overheating Thermal monitoring of cable terminations and busbars SF₆ gas leak detection (for gas insulated switchgear) Suppression: Gas suppression (FK 5 1 12 or inert gas) — no water near HV equipment Water mist only where HV equipment is fully enclosed and isolated No manual firefighting of energised HV equipment — isolate first Automatic isolation before suppression discharge (cause and effect matrix) Passive protection: Fire rated switchroom enclosure (minimum 120 minutes) Pressure relief venting for arc fault energy release Cable transit sealing at all penetrations Fire rated cable coating in HV cable routes Transformer bund walls containing oil spills Transformer Fire Protection Oil filled transformers are the highest fire risk electrical asset: Mineral oil insulation — significant fire load (thousands of litres) Deluge water spray systems — activated by heat detection Stone filled bunds — absorbing oil and preventing pool fire spread Blast walls between transformers — containing explosion pressure Fire resistant transformer oil (silicone or synthetic ester) increasingly specified Standards and Guidance BS EN 61936 1 — power installations exceeding 1kV AC ENA TS 09 02 — fire protection of substations NFPA 850 — fire protection for electric generating plants IEEE C2 — National Electrical Safety Code DSEAR — explosive atmosphere assessment for gas insulated switchgear For electrical installation fire engineering, contact Magnus Opifex. Magnus Opifex SEVEN LTD — UK's Leading Fire Safety & Fire Engineering Consultancy 🌐 magnus opifex.co.uk 📞 +44 7486 691724 ✉️ office@magnus opifex.co.uk Founders: Nicoleta Vasile, Baroness of Brattleby — CEO, Lawyer and Barrister, Legal & Administrative Director Alina — Technical Director & Expert Fire Engineer (BEng) Head Office: Ealing Cross, 85 Uxbridge Road, London W5 5BW Magnus Opifex SEVEN LTD delivers engineering led fire engineering, fire risk assessments, CFD modelling, and building safety consultancy across the United Kingdom and internationally. With over 20 years of combined experience and a UK portfolio spanning healthcare, residential and infrastructure, we bring truly engineered solutions with a personal touch. © 2026 Magnus Opifex SEVEN LTD. All rights reserved.