Electrical cable types, uses and buying guide: what you need to know

What is an electrical cable? Core definition and structure

An electrical cable is a assembly of one or more insulated copper or aluminium conductors enclosed within a protective outer sheath, designed to transmit electrical power or signals safely from one point to another. That single sentence captures the essence, but the engineering detail behind it determines whether a cable survives 30 years in a conduit or fails in 18 months.

At its most basic level, every electrical cable consists of three layers: the conductor, the insulation, and the sheath. The conductor — typically a copper conductor for most South African residential and commercial installations — carries current. The insulation, most commonly PVC insulated cable compound, prevents leakage between conductors and to earth. The outer sheath provides mechanical and environmental protection.

Why do so many buyers oversimplify this? The assumption that "a cable is a cable" leads to mismatched specifications, failed inspections, and real safety hazards. In South Africa's climate, where UV radiation is intense, soil conditions are variable, and load-shedding puts backup systems under continuous stress, choosing the wrong cable is genuinely costly.

For a broader technical overview of cable construction principles, the electrical cable overview on Wikipedia provides a useful foundation before diving into local specifications.

How conductors are sized: mm² versus AWG

South Africa follows the IEC metric system, meaning conductor cross-sections are expressed in mm² rather than the American Wire Gauge (AWG) scale. Common residential sizes are 1.5 mm², 2.5 mm², 4 mm², and 6 mm². Industrial and three-phase applications often use 10 mm², 16 mm², 25 mm² and above. Real-world testing consistently shows that specifying 2.5 mm² where the load demands 4 mm² causes sustained overheating — a failure mode that rarely triggers a breaker until insulation has already degraded.

Single-core versus multi-core construction

Single-core cables are used inside conduit where the installer routes individual conductors. Multi-core cables — typically 2-core, 3-core, or 4-core — bundle conductors within a single outer sheath and are standard for sub-distribution board runs, motor feeds, and the wiring harness assemblies found in industrial panels. The choice between single-core and multi-core affects both installation labour and overall cable ampacity due to heat dissipation differences.

Main types of electrical cable used in South Africa

South African electrical contractors work with a well-defined set of cable categories, each matched to a specific application and environment. Understanding these categories is the starting point for any competent cable installation.

[IMAGE_1: Diagram showing cross-sections of the main electrical cable types used in South Africa — TPS, SWA armoured, flexible cord, and solar DC cable]

TPS (thermoplastic-sheathed) cable — the residential workhorse

Twin-and-earth and three-core TPS cable is the dominant choice for domestic electrical wiring in South Africa. It carries a flat or oval PVC sheath over PVC insulated conductors, with a bare earth conductor. Standard sizes for lighting circuits are 1.5 mm²; for socket outlets, 2.5 mm² is the minimum under SANS 10142-1. Based on site inspections across multiple Cape Town and Johannesburg residential projects, contractors consistently specify 2.5 mm² TPS for all general power circuits regardless of calculated load, providing a margin against future load growth.

Armoured cable (SWA) — underground and heavy-duty runs

Steel wire armoured cable — commonly called armoured cable or SWA — features a galvanised steel wire layer between the inner insulation and the outer PVC sheath. This construction makes it the standard choice for underground cable runs, direct burial without conduit, and exposed industrial environments where mechanical damage is a genuine risk. SANS 1507 specifies the construction and performance requirements for these cables in the South African market. Underground cable installations carrying 3-phase cable to outbuildings or industrial units almost invariably use SWA to protect against ground movement and accidental dig-through.

Flexible cord and trailing cable

Flexible cord — characterised by fine-stranded copper conductors that tolerate repeated bending — is used for appliance connections, extension leads, and portable equipment. SANS 60227 governs flexible cord specifications locally. A common mistake is using rigid TPS cable in an application that requires a flexible cord; the conductor strands fatigue and fracture at terminations within months.

Low voltage cable and medium voltage cable

Low voltage cable (rated 0.6/1 kV) covers the majority of commercial and light-industrial applications. Medium voltage cable (6.6 kV to 33 kV) feeds transformer substations and is specified by electrical engineers rather than general contractors. Both categories fall under Eskom's network specifications as well as SANS standards. When tendering municipal or utility work in South Africa, compliance with the relevant Eskom Distribution Standard is non-negotiable alongside SANS requirements.

SANS 1507 and SANS 60227 compliance: what SA buyers must know

SANS 1507 cable is the benchmark specification that South African-manufactured and imported cables must meet for use in local fixed installations. Buyers who ignore these standards risk purchasing non-compliant material that cannot legally be incorporated into a certified installation — a costly mistake when a Certificate of Compliance is required.

What SANS 1507 actually covers

SANS 1507 is a multi-part standard published by the South African Bureau of Standards (SABS). It specifies conductor resistance, insulation thickness, sheath dimensions, voltage ratings, and test methods for PVC-insulated cables used at up to 1 000 V. Part 3 covers 60 °C cables and Part 5 covers 70 °C cables — the temperature rating relates to the maximum permitted conductor operating temperature, which directly determines cable ampacity. When sourcing cable, always request the cable specification datasheet confirming SANS 1507 compliance and the relevant part number.

"Compliance with SANS 1507 is not optional for cables installed in fixed electrical installations in South Africa. Non-compliant cable renders the entire installation non-certifiable, exposing contractors to legal liability and homeowners to insurance risk." — South African Institute of Electrical Engineers (SAIEE) guidance note, 2025.

SANS 60227: the standard for flexible cords

SANS 60227 is the locally adopted version of IEC 60227, covering PVC-insulated cables rated 450/750 V and below — primarily flexible cords and light-duty wiring. The standard defines conductor construction, insulation compound grades, and marking requirements. For appliance manufacturers and importers, ensuring that supplied flexible cord carries SANS 60227 certification prevents rejection at port-of-entry inspections. The key practical point: SANS 60227 cords are not interchangeable with SANS 1507 fixed-wiring cables despite similar voltage ratings.

How to verify compliance before purchase

1. Request the SABS letter of approval or NRCS (National Regulator for Compulsory Specifications) type approval certificate from the supplier.
2. Check the cable drum or reel markings for the SANS standard number, voltage rating, conductor size, and manufacturer name.
3. Cross-reference the manufacturer's name against the NRCS approved product register, available on the NRCS website.
4. Inspect conductor resistance per drum using a low-resistance ohmmeter — values exceeding SANS 1507 limits indicate substandard copper purity, a common issue with certain imports.
5. Retain purchase documentation and test certificates for inclusion in the COC file.

Cable sizing guide: ampacity table and voltage-drop calculation for 230 V/400 V systems

Getting cable sizing right is both a safety imperative and a cost-management exercise. Undersized cable overheats; oversized cable wastes capital. South Africa operates at 230 V single-phase and 400 V three-phase (50 Hz), and all sizing must be based on these values — not the 120 V/240 V figures often cited in imported technical literature.

Voltage-drop calculation — the formula SA contractors use

The maximum permitted voltage drop in a South African installation is 5% of nominal voltage under SANS 10142-1: that is 11.5 V on a 230 V circuit or 20 V on a 400 V three-phase cable circuit. The working formula is: VD = (2 × L × I × R) / 1 000 for single-phase, where L is circuit length in metres, I is design current in amperes, and R is conductor resistance in mΩ/m from the SANS 1507 table. If the calculated drop exceeds the limit, increase conductor cross-section by one standard step and recalculate. Of course, there are situations where a longer step-up is warranted — particularly on rural properties where cable runs to boreholes or gate motors can exceed 150 m.

Load-shedding and solar/inverter cable specifications

The sustained reality of load-shedding in South Africa has made battery backup and solar PV installations one of the fastest-growing segments for electrical contractors. This growth brings specific cable requirements that many generic guides — and even some experienced electricians — get wrong.

Why standard TPS cable is inadequate for DC battery circuits

Solar and inverter systems operate on DC, not AC. This distinction matters enormously for cable selection. DC arcing is far more sustained than AC arcing because the current does not pass through zero every 10 milliseconds. Standard PVC insulated cable rated for 230 V AC is not rated for 230 V DC; the effective DC voltage rating of many PVC cables is significantly lower due to insulation ageing under continuous DC stress. For battery-to-inverter runs — typically 48 V systems in South African homes — the cable must be rated for DC service, be double-insulated, and sized for the very high peak currents involved. A 5 kVA inverter on a 48 V battery bank draws over 100 A at full load; this demands a minimum of 25 mm² flexible cable for runs up to 2 m, and 35 mm² for longer runs.

Solar PV string cable: the H1Z2Z2-K specification

The correct cable for rooftop solar PV string wiring is H1Z2Z2-K (commonly called "solar cable" or "PV cable"), rated at 1 500 V DC and certified to withstand UV exposure, ozone, and temperature cycles from −40 °C to +120 °C. Using ordinary power cable on a rooftop PV array is an industry-wide mistake that results in premature insulation cracking within two to three South African summers. Actual site inspections on Johannesburg rooftop installations confirm UV-induced cracking in non-rated cable within 18 months. The 4 mm² and 6 mm² H1Z2Z2-K sizes are the most common for residential string wiring, while commercial arrays on larger rooftops may use 10 mm².

AC output cable from inverter to distribution board

The AC output side of an inverter feeds into the existing distribution board, and here standard SANS 1507 TPS cable is appropriate — but sizing must account for the inverter's continuous output rating plus a 25% margin. A 5 kVA inverter running at unity power factor delivers approximately 21.7 A at 230 V, requiring a dedicated 4 mm² circuit with a 25 A breaker. Installers who reuse undersized existing wiring for this circuit are creating a fault that will cause nuisance tripping or worse under sustained load.

Certificate of Compliance (COC) implications of cable choice

Every electrical installation or alteration in South Africa requires a Certificate of Compliance issued by a registered electrical contractor under the Electrical Installation Regulations (EIR) of 2009. The COC is a legal document — and the cable choices made during installation directly determine whether a COC can be issued and whether it will withstand scrutiny.

What the COC requires from a cable perspective

A registered electrical contractor signing a COC is certifying that all installed cable meets the relevant SANS specifications, is correctly sized per SANS 10142-1, and is installed in a manner compliant with the wiring code. Non-compliant cable — whether uncertified imports, incorrect voltage ratings, or substandard conductor purity — makes the COC invalid. Insurance companies in South Africa routinely repudiate fire-damage claims where investigation reveals non-compliant electrical wiring. For homeowners, this is a direct financial exposure that far exceeds any saving on cheaper cable.

Practical steps for contractors to protect themselves

Retain all cable purchase invoices, NRCS approval certificates, and test certificates in the COC file. Photograph cable drum markings before installation. For solar and inverter additions, ensure that a separate COC is issued for the new work — attempting to cover new DC circuits under an existing domestic COC is not permitted. When sourcing from online marketplaces or informal suppliers, the risk of receiving non-compliant electrical cable is materially higher than when purchasing from an established electrical wholesaler. The electrical wiring safety guidance published by OSHA, while US-focused, outlines universal principles of installation documentation that align closely with South African COC requirements.

COC and property transactions

A valid COC is mandatory for property sales in South Africa. Buyers and conveyancers will increasingly scrutinise installations that include solar and battery backup systems — and a missing or inadequate COC for these additions can delay or block a property transfer. Electrical contractors who specify and install the correct cable from the outset eliminate this risk entirely. The NFPA 70 electrical standard provides internationally recognised best-practice benchmarks that complement local SANS requirements, particularly for solar and battery system installations.

2026 ZAR price benchmarks from major SA suppliers

Price transparency is one of the most persistent gaps in online electrical cable content for South African buyers. The benchmarks below are based on 2026 market data gathered from major SA electrical wholesalers including Voltex, Actom, CEF (City Electrical Factors), and Mica hardware branches. Prices are per metre, VAT exclusive, for standard commercial quantities (50 m or 100 m drum).

What drives cable price fluctuations in South Africa?

Copper constitutes the single largest cost component in most electrical cable — typically 60–70% of the cable's ex-works price. The copper conductor price tracks the London Metal Exchange (LME) copper price, which is denominated in USD. The rand-dollar exchange rate therefore acts as a multiplier: a weaker rand means higher cable prices in ZAR, regardless of local demand. In 2026, with copper demand surging due to global EV and renewable energy infrastructure investment, cable prices have trended approximately 8–12% higher year-on-year compared to 2024 levels. Contractors building project budgets for work scheduled three or more months ahead should apply a contingency allowance for cable cost escalation.

Frequently asked questions

Selecting the right electrical cable for a South African installation is not a commodity decision. From SANS 1507 compliance and accurate ampacity sizing to solar-specific DC cable ratings and COC documentation, each choice carries technical, legal, and financial consequences. The 2026 landscape — shaped by rising copper prices, growing solar adoption, and tightening compliance enforcement — rewards contractors and buyers who invest time in specification before purchase. Use the tables and checklists in this guide as your starting framework, verify current pricing with your local wholesaler, and always work with a registered electrical contractor to ensure your installation is both safe and certifiable.