Selecting the correct cable for your electrical installation is critical for safety, performance, and compliance with BS 7671 wiring regulations. This comprehensive guide from Cable Services UK, the UK's No.1 specialist electrical cable supplier, provides expert recommendations to help you choose the right cable for your specific application.
With over 50 years of experience supplying premium electrical cables and equipment, we've compiled this selection chart to assist engineers, contractors, and electrical professionals in making informed decisions.
Need help selecting the right cable?
Use our free Cable Size Calculator or speak with our expert technical team
Launch Cable CalculatorLow Voltage Cable Selection Chart (up to 1000V AC)
| Cable Type | Voltage Rating | Typical Applications | Installation Method | Key Features |
|---|---|---|---|---|
| 6491X (Single Core) | 600/1000V | General wiring, distribution boards, switch panels | Conduit, trunking, traywork | PVC insulated, economical, widely used |
| 6242Y / 6243Y (Twin & Earth) | 300/500V | Domestic fixed wiring, lighting circuits, socket outlets | Concealed in walls, under floors, in lofts | Flat grey cable, CPC (circuit protective conductor) |
| SWA (Steel Wire Armoured) | 600/1000V | Underground burial, external installations, industrial power distribution | Direct burial, outdoor, harsh environments | Mechanical protection, earthing armour, XLPE or PVC |
| NYY-J / NYM-J | 600/1000V | Power distribution, industrial installations | Indoor/outdoor fixed installations | PVC sheathed, suitable for direct burial |
| H07RN-F (Rubber Flex) | 450/750V | Construction sites, portable equipment, temporary power | Outdoor, flexible applications | Rubber insulated, oil & weather resistant |
| FP200 Gold / FP Plus | 300/500V | Fire alarm systems, emergency lighting, safety circuits | Fixed wiring in safety critical systems | Fire resistant, maintains circuit integrity |
| LSZH (LS0H) | 600/1000V | Public buildings, enclosed spaces, underground railways | Indoor installations where smoke emission is critical | Low smoke, zero halogen, reduced toxic fumes |
| Cat 5e / Cat 6 / Cat 6a | Data Cable | Data networks, telecommunications, structured cabling | Trunking, containment systems | Twisted pair for data transmission |
Medium & High Voltage Cable Selection (above 1000V AC)
| Cable Type | Voltage Rating | Typical Applications | Installation Method | Key Features |
|---|---|---|---|---|
| 6.35/11kV XLPE SWA | 11kV | Distribution networks, substations, industrial power | Underground, ducts, cable trenches | XLPE insulation, steel wire armour, DNO approved |
| 12.7/22kV XLPE SWA | 22kV | High voltage distribution, large industrial sites | Underground installation, cable tunnels | Higher voltage capability, increased power transmission |
| 19/33kV XLPE SWA | 33kV | Grid connections, power generation, transmission networks | Underground, specialist installation | High voltage transmission, specialist terminations required |
| PILC (Paper Insulated Lead Covered) | 11-33kV | Legacy installations, older distribution networks | Underground (being phased out) | Traditional technology, typically being replaced with XLPE |
π‘ Important Cable Selection Considerations
1. Current Carrying Capacity: Always calculate the load current and apply derating factors for ambient temperature, grouping, and installation method.
2. Voltage Drop: Ensure voltage drop complies with BS 7671 requirements (typically 3% for lighting, 5% for other uses).
3. Short Circuit Protection: Cable must withstand fault currents without damage until protective device operates.
4. Environmental Conditions: Consider temperature, moisture, chemical exposure, UV radiation, and mechanical stress.
5. BS 7671 Compliance: All selections must comply with current wiring regulations (18th Edition as amended).
Cable Selection by Application
ποΈ Construction & Building Sites
- H07RN-F rubber flex for temporary power
- SWA cables for site distribution
- Arctic grade cables for cold environments
- 110V centre-tapped earth systems
β‘ Utilities & DNO Applications
- 11kV/33kV XLPE SWA cables
- Waveform cable for underground distribution
- CNE (Combined Neutral & Earth) cables
- Specialist jointing & termination kits
π Rail & Transport
- BS 7846 LSZH cables for rolling stock
- BS 6387 fire survival cables
- Trackside signalling cables
- Traction power cables
π EV Charging Infrastructure
- SWA cables for EV charger feeds
- Mode 3 EV charging cables
- Weather-resistant outdoor cables
- High current capacity conductors
π Oil, Gas & Petrochemical
- ATEX/IECEx certified cables
- Flame retardant armoured cables
- Chemical resistant sheaths
- Instrumentation & control cables
π± Renewable Energy
- Solar PV cables (DC rated)
- Wind turbine power cables
- UV resistant outdoor cables
- High temperature rated conductors
β οΈ Critical Safety Information
Professional Installation Required: Electrical installations must be carried out by qualified, competent persons in accordance with BS 7671.
Testing & Certification: All installations require proper testing and certification by a registered electrician.
Consult Technical Support: For complex installations or specialist applications, always consult with our technical team before cable selection.
Cable Installation Methods & Reference Methods
| Reference Method | Description | Typical Cables | Derating Considerations |
|---|---|---|---|
| Method A | Enclosed in conduit in thermally insulated wall | 6491X singles in conduit | Significant derating required |
| Method B | Enclosed in conduit/trunking on wall or in masonry | 6491X, multi-core cables in conduit | Moderate derating |
| Method C | Clipped direct to non-metallic surface | 6242Y Twin & Earth, SWA cables | Good heat dissipation |
| Method D | Direct in ground or ducts in ground | SWA armoured cables, XLPE cables | Soil thermal resistivity critical |
| Method E/F/G | On cable tray, ladder, or in free air | SWA, singles on tray systems | Best heat dissipation |
π Using Our Free Cable Calculator
Take the guesswork out of cable selection! Our BS 7671 compliant cable calculator automatically:
- Calculates correct cable size based on load and installation method
- Applies appropriate derating factors
- Checks voltage drop compliance
- Verifies earth fault loop impedance
- Provides instant, accurate results
Why Choose Cable Services UK?
β 50+ Years Experience
Established in 1971, we're the UK's most trusted supplier of specialist electrical equipment.
β Market-Leading Brands
We stock cables from Prysmian, Nexans, NKT, and other premium manufacturers.
β Technical Expertise
Our in-house technical team provides expert guidance for every project.
β Nationwide Coverage
Five branches across the UK: Wrexham, Glasgow, Liverpool, Stone, Swindon, and Guildford.
β Custom Solutions
Cable cutting and kitting services for project-specific requirements.
β Training Facilities
State-of-the-art product familiarisation training in Wrexham and Glasgow.
Need Expert Advice on Cable Selection?
Our technical team is ready to help you choose the right cable for your project
π Call us: 01978 340450 | π§ Email: sales@cableservices.co.uk
Mon-Fri: 8:00-5:30
