SANS 10142-1 and SPDs: what inspectors expect

How SANS 10142-1 treats surge protective devices, what a compliant SPD install looks like on a SA board, and the COC and NRCS LOA evidence inspectors expect.

title: "SANS 10142-1 and SPDs: what inspectors expect" description: "How SANS 10142-1 treats surge protective devices, what a compliant SPD install looks like on a SA board, and the COC and NRCS LOA evidence inspectors expect." date: "2026-06-11" author: "EBB South Africa" tags: ["SANS 10142-1", "surge protection", "COC", "NRCS", "compliance"] draft: false

If you wire premises in South Africa, you work to SANS 10142-1, the wiring code for low-voltage installations. It is the standard behind every Certificate of Compliance (COC), and it is the document an electrical inspector reaches for when something on a board looks wrong. Surge protective devices (SPDs) now sit squarely inside that code, and a growing number of installations are flagged not because the SPD is missing, but because it is the wrong type, wired the wrong way, or carries no proof that it may legally be sold here.

This article walks through what SANS 10142-1 actually requires of an SPD, what a compliant install looks like on a real board, and the paperwork an inspector will want before they sign your COC.

What SANS 10142-1 does — and where SPDs fit

SANS 10142-1 governs the wiring of premises: how an installation is built, earthed, protected and verified before it is energised and handed over. It is the practical companion to the product standard, SANS 61643-11 (the South African adoption of IEC 61643-11), which governs the SPD as a device — its type-test class, its discharge ratings, its let-through voltage.

The two standards do different jobs, and an inspector checks both. SANS 61643-11 tells you whether the device on the rail is a genuine, tested SPD. SANS 10142-1 tells you whether it has been selected and installed correctly for the board it sits on. A perfectly good Type 2 arrester installed in the wrong place, with the wrong earthing reference or 600 mm of looped conductor, fails the wiring code even though the product itself is sound.

For the selection and coordination logic behind these rules, IEC 61643-12 (selection and application) is the reference both standards lean on.

What a compliant SPD install looks like

An inspector is not looking for one box. They are looking for a coordinated protection scheme that matches the building's risk and earthing system. A few things they consistently check:

The right type in the right position. Surge protection is layered. Where a structure has a lightning protection system (LPS) or a direct-strike risk at the service entrance, a Type 1 (Class I) device — tested to the 10/350 µs impulse waveform and rated by its Iimp — belongs at the main entry. Downstream, on the distribution boards that feed the actual loads, a Type 2 (Class II) device tested to the 8/20 µs waveform and rated by In and Imax does the everyday work of clamping induced surges and switching transients. Most South African DBs need a Type 2 arrester on every live phase; the EBB PZ-C 275/40 is exactly that device: a single-module, 18 mm DIN Type 2 unit rated Uc 275 V, In 20 kA, Imax 40 kA, holding the let-through voltage to ≤1.2 kV. (Our decoder breaks down what each of those codes means on the marking plate.)

Matched to the earthing system. TN-S, TN-C-S and TT installations are not wired the same way for surge protection. On a TT system in particular, the neutral-to-earth (N-PE) path needs its own protective component, typically a gas-discharge tube in a 3+1 arrangement, rather than the same MOV path used phase-to-neutral. An inspector who sees a flat three-pole arrangement on a TT board where a 3+1 is expected will ask why.

Short, straight connecting leads. This is where good devices fail inspections. The let-through voltage an SPD actually delivers to the protected equipment is its Up plus the inductive voltage rise along its own connecting conductors. The code's intent is the classic "500 mm rule": keep the total length of the SPD's phase and earth connections as short and straight as practical — ideally under half a metre combined — so the residual voltage stays close to the device's rated Up. Long, looped or shared leads quietly defeat a correctly chosen arrester.

Correct overcurrent and disconnection coordination. The SPD must be backed by the protective device the manufacturer specifies, and its own internal thermal disconnector must be able to take the SPD safely offline at end of life without dropping the circuit. End-of-life indication (a visual flag, or a remote dry-contact on the "R" variants) is what lets that condition be found before the protection is gone. A replaceable-module design (the MODULE cartridges in the range) lets a worn unit be swapped without rewiring the base, which keeps a long-lived board compliant over its life.

The COC implication

The Certificate of Compliance is the registered person's signed declaration that the installation conforms to SANS 10142-1 at handover. Where surge protection is required (by the design, by an LPS risk assessment, or by a client specification), the SPD is part of what that signature covers. Three consequences follow:

An incorrectly selected or installed SPD is a COC defect. It does not matter that a device is physically present; if it is the wrong type for its position, mismatched to the earthing system, or connected with excessive lead length, it does not satisfy the code, and the registered person should not certify around it.
The device itself must be a legal product. This is where the COC meets the NRCS regime (see below). An SPD with no Letter of Authority is not lawfully sold in South Africa, and certifying an installation built around non-compliant goods is a problem for the person who signs.
The evidence must be retrievable. Inspectors, insurers and tender QA files increasingly ask for the documentation behind the device, not just its presence on the rail. "Certification available on request" is not the same as a downloadable LOA and test report. Our compliance page keeps that evidence in one place.

Where NRCS and the LOA come in

SPDs in South Africa fall under a compulsory specification, VC 8055, administered by the National Regulator for Compulsory Specifications (NRCS). That makes a valid NRCS Letter of Authority (LOA) a precondition for legally selling the device here. The LOA is the regulator's confirmation that the product, with its specific model numbers and technical ratings, has been assessed against the compulsory spec and the underlying SANS / IEC test standard.

This is a separate question from the wiring code. SANS 10142-1 asks was it installed correctly; the NRCS LOA asks was it legal to sell in the first place. A compliant job needs both to be true, and a careful inspector or QA reviewer will look for both.

For the EBB PZ-C 275/40 Type 2 family, the relevant NRCS approval is recorded under reference ZAF-RCC-0029482, issued under VC 8055, with the product tested to SANS / IEC 61643-11 (Class II, 8/20 µs). When you ask EBB for the documentation pack, that is the LOA reference and the test-report set you receive — matched to the SKUs you actually bought.

A practical pre-COC checklist

Before you energise and certify, a quick pass:

Is there a Type 1 (or Type 1+2) device at the entry where the LPS / direct strike risk calls for one, and a Type 2 on the distribution boards feeding the loads?
Is the configuration matched to the earthing system — including a dedicated N-PE path on TT?
Are the SPD's connecting leads short and straight (the ~500 mm intent)?
Is the SPD backed by its specified overcurrent protection, and is end-of-life indication present and visible?
Do you hold the NRCS LOA and SANS 61643-11 test report for the exact device installed, ready for the QA file?

If you can answer yes to all five, the SPD side of your SANS 10142-1 COC is in good shape.

In short

SANS 10142-1 treats surge protection as part of a compliant installation, not an optional extra. The wiring code decides whether the device was installed correctly; the NRCS LOA decides whether it was legal to sell. Inspectors check both, and the registered person's COC signature now reaches across both questions.

EBB supplies NRCS-approved Type 2 surge protection with the LOA and test reports to back it. If you are specifying for a board, a tender or a QA file, the products catalogue, the decoder and the compliance library will get you most of the way. Our onboarding process matches the documentation to your exact SKU list.