Commercial & industrial · CHAS accredited
Three-phase installations, fit-outs, warehouse LED and maintenance across Mid Somerset — delivered with minimal downtime and full certification.
NAPIT
CHAS
City & Guilds
TrustMark
Part P
BS 7671
One contractor, one handover
From offices and shops to factories and farms, we deliver clean installs on time — with the paperwork facilities managers and insurers need.
What we deliver
Supplies, distribution boards and machinery wiring.
Cable tray, basket and trunking, cleanly installed.
High-bay and factory LED for lower bills and better light.
Full first & second fix for offices, retail and units.
Minimal downtime
We plan around your operation — out of hours where needed — so the lights stay on and the business keeps running.
See commercial work →How we work
FAQ
Yes — we’re CHAS accredited and fully insured, with the documentation facilities managers and insurers require.
Yes. For fit-outs and maintenance we regularly work evenings and weekends to avoid disrupting your business.
We do — planned maintenance, periodic EICRs and a priority line for contract clients.
Yes. We handle new three-phase supplies from 60A to 400A+, single to three-phase upgrades, TPN distribution, load balancing, and full DNO coordination.
Commercial premises should have an EICR every 5 years, or every change of occupancy. Some industries may need more frequent testing.
Yes. We regularly work evenings, weekends, and overnight shutdowns to minimise business disruption. Included in the quote at no extra charge.
Commercial services in depth
From small retail units to large industrial warehouses — every installation designed, installed and certified to the same standard.
New three-phase supplies, upgrades and load balancing for commercial and industrial premises. TPN distribution boards, CT metering, maximum demand calculations. Full DNO coordination and applications handled.
Commercial DB design, installation and upgrades. Hager and Schneider boards with RCBO protection, Type A RCDs, surge protection (SPD Type 1+2) and clear circuit labelling to BS 7671. From single-phase domestic to multi-board commercial.
PLC cabinets, motor control centres, VFD installations and bespoke control panels. Designed, built, wired and commissioned on site. Full documentation and circuit diagrams provided.
Busbar trunking, galvanised cable tray, ladder rack, SWA armoured cabling and sub-main distribution. Complete containment systems for factories, warehouses and commercial units.
LED high bay and low bay luminaires for warehouses, storage units, distribution centres and workshops. 100–240W linear and UFO high bays, 80–120W low bay for lower eaves, DALI or wireless zone control. Sensor-based occupancy control to cut running costs by up to 60%. Full lux-level calculations to CIBSE LG1.
PIR floodlights, bollards, car-park lighting, loading-bay illumination and security floods for commercial premises and yards. IP65+ rated fittings, photocell or dusk-to-dawn control, SWA armoured supplies, outdoor-rated isolators. Designed to deter intruders and meet insurance specifications.
Commercial Wi-Fi (Reyee & Ruijie), PoE switching, comms cabinets, structured Cat6/Cat6a cabling, fibre optic backbones. Schools, surgeries, factories, offices, libraries. Full network infrastructure page →
Looking for something else? We cover network infrastructure (Wi-Fi APs, PoE switching, cabinets), commercial & emergency lighting, fire alarms, EICR testing, fibre optic, CCTV & access control, maintenance contracts and office fit-outs on dedicated pages.
Three-phase power
Three-phase power is the backbone of any serious commercial or industrial premises. We design, install and commission complete three-phase systems sized for your current demand and future growth.
Every three-phase installation starts with a maximum demand calculation. We assess every load on the premises — machinery, HVAC, lighting, socket circuits, kitchen equipment — and calculate total demand in kVA across all three phases. This determines your incoming supply size and ensures balanced loading across L1, L2 and L3 to prevent neutral overloading and voltage imbalance.
We install TPN (Triple Pole and Neutral) distribution boards with careful phase allocation. Single-phase loads are distributed evenly across the three phases to maintain balance within 10–15% — critical for motor longevity and power quality. Three-phase loads such as compressors, large HVAC units and industrial machinery connect directly through TP isolators with appropriate overload protection.
From a new 100A three-phase supply for a small workshop to a 400A+ supply feeding an industrial unit, we handle the complete process: DNO liaison, meter position, main switch, distribution, sub-mains and final circuits. Every installation is designed with diversity applied correctly and fault levels calculated so protective devices operate within disconnection times.
Distribution & protection
The distribution board is the heart of any commercial installation. We specify, install and label boards from Hager, Schneider Electric and ABB — trusted across the industry for reliability and component availability.
For commercial installations we specify individual RCBOs on critical circuits. Each circuit gets its own overcurrent and earth leakage protection, so a single fault does not trip an entire bank — essential where loss of power to refrigeration, servers or EPOS means lost revenue. Where budget requires it, we use split-load boards with MCBs protected by upstream RCDs — but always with careful circuit grouping so a trip on one RCD does not take out both lighting and power in the same area.
Type A RCDs detect sinusoidal AC earth leakage and pulsating DC fault currents — required by BS 7671 for circuits feeding IT equipment, LED drivers and EV chargers. Modern EV chargers (Hypervolt, Ohme, Zappi, Easee) have integral 6mA DC fault detection, so Type A RCBOs on the supply side are correct for every install we carry out. Type AC alone is no longer acceptable under the 18th Edition.
Type 1+2 SPDs installed at the origin of supply protect against direct lightning strikes and indirect surges. BS 7671 requires a risk assessment for SPD provision on every new installation — for commercial premises, the answer is almost always yes. We install SPDs with backup fuse protection and short cable runs to the main earth bar, with Type 3 SPDs added at point-of-use for sensitive equipment such as server rooms.
Cables & containment
The right cable in the right containment, installed to the right standard. Cable types selected on environment, fire risk and regulatory requirements.
Properly specified containment protects cables, simplifies future maintenance and ensures fire stopping compliance.
Life safety systems
Emergency lighting is a legal requirement in virtually every commercial premises. We design, install, test and certify systems compliant with BS 5266 and the Regulatory Reform (Fire Safety) Order 2005.
Self-contained units have individual batteries within each luminaire. Most common for smaller premises — each unit independent. Typical battery life 3–4 years.
Central battery systems use a single battery bank feeding all emergency luminaires via FP200 fire-rated cable. Better for large premises — easier to maintain, longer battery life, consistent output.
Maintained vs non-maintained: maintained fittings illuminate at all times, switching to battery on mains failure — required in cinemas, theatres and entertainment venues. Non-maintained only illuminate on mains failure — standard for offices, shops and most commercial buildings.
BS 5266 mandates a strict testing regime. We provide testing contracts and issue emergency lighting certificates.
Fire detection
We design, install, commission and maintain fire alarm systems for all commercial premises. Every system designed to the appropriate BS 5839-1 category using FP200 fire-rated cabling.
BS 5839-1 categories determine detection coverage, set by the fire risk assessment:
Conventional divides the building into zones — the panel shows which zone, not which detector. Good for smaller premises.
Addressable gives every device a unique address, so the panel identifies the exact detector location. Essential for larger buildings.
Cause and effect: specific detectors trigger specific actions — kitchen detector = local sounder only; server room = HVAC damper shutdown; fire doors release by zone.
Testing & maintenance
Keeping your installation safe, compliant and efficient — one-off EICRs and ongoing planned preventive maintenance.
Commercial premises need an EICR every 5 years minimum — a legal requirement under the Electricity at Work Regulations 1989.
Scheduled visits to inspect, test, service and maintain your entire electrical installation. No unexpected downtime.
Sectors we serve
By sector, what changes
Display LED with high CRI for true colour rendering, dimmable feature lighting, dedicated EPOS / chip-and-pin clean-earth circuits, anti-shoplifting CCTV integrated with door entry. Out-of-hours work to keep trading.
Kitchen 3-phase distribution with TPN board, RCBO Type A on every circuit, cooker / fryer / extractor isolators, mains-wired fire alarm to BS 5839 Pt 1, BS 5266 maintained emergency lighting on all escape routes. EICR before insurance renewal.
LSOH (low-smoke zero-halogen) cabling throughout, DBS-cleared engineers, safeguarding-aware site conduct, holiday-only major works, ICT suite power and structured cabling, lectern AV and dimmable hall lighting.
Clean-earth medical-grade circuits for chair-side and treatment equipment, CQC-aligned emergency lighting, dedicated UPS protection on records / imaging, infection-control aware containment specification.
100A–400A+ three-phase supplies, TPN distribution with phase balancing, motor circuits with overload and soft-start, IP65 high-bay LED with occupancy zoning, machinery isolators and emergency stops.
If you run several sites and want one electrician on retainer for EICR, emergency lighting, fire alarm and reactive callouts, see our commercial maintenance contracts for fixed-price quarterly visits and SLA response times.
Every price covers the whole job, not just time on site
Areas we cover
What customers say
“I had a brilliant experience using Dan for a full revamp of the electrics ready for the new kitchen. It was a large project and he explained things clearly and gave me options.”
“Dan and his team did a fantastic job upgrading everything in my flat. Professional, tidy, and excellent quality work throughout.”
“Dan arrived on time, completed the job in a professional and speedy way. There was no mess to clean up. I would highly recommend.”
Get a quote
Offices, retail, warehouses, farms — tell us the scope and we’ll propose a plan.
DS Electrical Installations (SW) Ltd will call you back to talk through the job.
