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South Africa’s Transmission Development Plan (TDP) aims to build approximately 14,500 km of new transmission lines and 105 substations by 2030, representing an investment of ZAR 400 billion. The first phase of Independent Transmission Projects (ITP) has already identified 1,164 km of priority corridors.
If you are sourcing 30/36kV medium voltage cables for South African projects, here are 5 things worth knowing:
1. South Africa has its own cable standard, SANS 1339 — not IEC. Eskom requires all XLPE-insulated MV cables to comply with this standard.
2.Eskom conducts independent factory sample evaluations on-site, per SANS 1339 — not just a paper review of certificates.
3. Substandard imported cables are a real risk in South Africa, with lab tests revealing conductor resistance exceeding specifications, insufficient insulation thickness, and substandard materials.
4. South Africa‘s climate requires UV-resistant cables — without UV stabilisers, cables degrade rapidly.
5. From 20 September 2026, cables imported from China must be accompanied by a Certificate of Conformity (CoC) — failure to provide this risks customs detention.
The 14,500km of new lines and 105 new substations outlined in the TDP represent a scale far beyond routine municipal planning. The first phase of ITP is now in implementation, covering 1,164km of priority 400kV corridors. These projects represent a sustained source of MV cable demand over the coming years.
Eskom procures MV cables through “as-and-when-required“ framework contracts, typically lasting 3 to 5 years. After award, Eskom places orders in tranches based on actual needs — not as a single bulk delivery.
SANS 1339 is the compulsory standard for medium voltage XLPE-insulated cables in South Africa, covering ratings from 6.6kV to 33kV. Eskom‘s safety specification VC 8077 explicitly requires all XLPE-insulated MV cables to comply with SANS 1339.
Eskom conducts on-site factory sample evaluations — suppliers must complete sample manufacturing and testing at their factory in accordance with SANS 1339. If Eskom has evaluated the same supplier and product within the last 7 years with no changes to design, process, or raw materials, the historical report may be reused. Otherwise, the supplier must complete sample preparation and evaluation within one month. Only after passing the evaluation can the supplier proceed to the quotation stage.
Quality Risks
Independent lab tests have identified conductor resistance exceeding specifications, insufficient insulation thickness, and substandard materials in multiple locally manufactured and imported cables. Failures caused by substandard cables are threatening the reliability of South Africa‘s grid.
South Africa‘s cable identification system has clear specifications — red stripe (flame-retardant PVC), blue stripe (low-halogen flame-retardant), white stripe (low-smoke zero-halogen) — but testing has revealed instances where blue stripe cables were substituted for white stripe cables at installation sites. Cable verification requires specialised equipment that not all suppliers possess.
The consequences of such failures are downtime, fire, and replacement costs — typically far exceeding any initial savings from lower purchase prices.
Compliance Risks
From 20 September 2026, cables imported from China must be accompanied by a Certificate of Conformity (CoC), or risk customs detention.
South Africa‘s climate is characterised by extreme heat, intense UV radiation, and high humidity. Imported cables often lack UV stabilisers. South African cable industry bodies have noted that non-compliant imported cables “deteriorate under South Africa’s harsh climate, leading to arcing, overheating, and efficiency losses.“
A cable that performs well in a temperate climate can fail within years under South African sunlight. South African procurement specifications explicitly require this, but a supplier‘s “complies with international standards“ statement does not automatically cover it.
SANS 1339 specifies both longitudinal and radial water blocking requirements — but radial water blocking only applies when explicitly specified by the user.
Longitudinal water blocking uses water-swellable yarns and tapes within the cable construction to prevent water from penetrating along the cable length. This is the most common method in the South African market.
Radial water blocking uses an impermeable concentric layer around the cable to prevent water from entering radially. However, radial water blocking is not common for MV cables in South Africa — it is typically specified for 44kV-132kV HV cables. If a project is in an area with a high groundwater table, buyers need to proactively specify radial water blocking — the standard will not automatically include it.
When XLPE insulation is exposed to moisture, water trees form and cause premature cable failure. XLPE cables are designed for a service life typically exceeding 30 years, but once water ingress occurs, that lifespan is significantly shortened.
SANS 1339 has a technical alignment with IEC 60502-2 to a certain extent, but the critical difference lies in South Africa‘s independent mandatory compliance requirements. Eskom’s safety specification VC 8077 explicitly requires all XLPE-insulated MV cables to comply with SANS 1339. Eskom‘s tender documents require factory sample evaluations to be performed in accordance with SANS 1339 and/or SANS 1507-3. Even if a supplier holds IEC certification, if the cable has not undergone type testing and factory evaluation per SANS 1339, it may still fail Eskom’s acceptance process. South Africa has an independent compliance path — IEC certificates cannot automatically substitute for SANS certification.
Eskom requires bidders to provide exact replicated samples of each cable type for factory evaluation. The evaluation is performed at the cable manufacturing facility in accordance with SANS 1339 and/or SANS 1507-3. Bidders must ensure that samples are manufactured, tested, and ready for evaluation within one month of receiving Eskom‘s notification. If the same supplier and product have been evaluated within the previous 7 years with no changes to design, process, or raw materials, the historical report may be reused. This process has a direct impact on supplier production planning — if a supplier has not previously passed Eskom’s evaluation, the timeline from bid to supply qualification may take several months.
Independent laboratory tests have identified several recurring issues: use of non-compliant polymers resulting in unsafe cables; incorrect marking — for example, marking flame-retardant PVC as low-halogen flame-retardant or even LSZH (such as printing blue or white stripes on the outer sheath when the inner cores and bedding do not meet the corresponding standards); and contractors substituting blue-striped cables for white-striped cables at installation sites to reduce costs. These non-compliance issues mean the cables may release more toxic smoke and corrosive gases in a fire, posing a direct threat to personnel and equipment.
Longitudinal water blocking uses water-swellable yarns and tapes installed within the cable construction to prevent water from penetrating along the cable length. Radial water blocking uses an impermeable concentric layer around the cable to prevent water from entering radially. Longitudinal water blocking is the most common method in the South African market. However, radial water blocking is not common for MV cables in South Africa — it is typically specified only for 44kV-132kV HV cables. SANS 1339 specifies that radial water blocking only applies when explicitly required by the user. If a project is in an area with a high groundwater table or the cable will be exposed to prolonged humid environment, buyers need to proactively specify radial water blocking — the standard will not automatically include it.
South Africa requires that specific products imported from China must be accompanied by a Certificate of Conformity (CoC) confirming compliance with South African national standards. This policy takes effect on 20 September 2026. Cables are among the affected product categories. Conformity assessment is conducted through a cooperation arrangement between the South African Bureau of Standards (SABS) and the China Certification and Inspection Group. Unregistered products will face customs detention. For buyers, this means procurement contracts should explicitly require suppliers to provide CoC certificates and include them as mandatory documents for acceptance upon delivery.
South Africa‘s grid expansion is underway. By understanding the standards, evaluating quality risks, and staying ahead of compliance requirements, procurement professionals can make confident decisions when participating in this growing market.
If you have a specific project in mind and would like to discuss further, feel free to reach out.
Tel: +86-371-6054 7601
WhatsApp / WeChat: 0086 135 9887 3045
Email: Admin@cncablegroup.com
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