The maximum resistance of the earth continuity path, by the rating of the protective device. This is the number an inspector reads off your test report.
Match the breaker on the circuit, not the cable and not the load. Above 63 A the table stops and Table 6.28 takes over.
Measured at the standard test current between the DB earth terminal and the earthing terminal of each point of consumption. SANS 10142-1 8.6.3 and Table 8.1.
Table 8.1, as amended. Nothing is interpolated: if the device is not in this list, pick the next rating up or fall back to Table 6.28 above 63 A.
| Device | Max ECC resistance |
|---|---|
| 6 A | 1,533 Ω |
| 10 A | 0,920 Ω |
| 16 A | 0,575 Ω |
| 20 A | 0,460 Ω |
| 25 A | 0,368 Ω |
| 32 A | 0,288 Ω |
| 40 A | 0,230 Ω |
| 45 A | 0,204 Ω |
| 50 A | 0,184 Ω |
| 63 A | 0,146 Ω |
SANS 10142-1 Table 8.1 (Ed 3.3 public-enquiry draft, table marked Amdt 2). Values sit in a licensed standard: check the clause against your own copy before you sign.
The clause is specific about the two ends of the measurement, and sparkies get caught on the second one.
8.6.3. Every point, not a sample. That is what makes a full-board continuity sweep the slow part of a CoC.
Sockets: the clause requires all socket-outlets to be tested by inserting a plug, so the resistance of the earth pin is included in the reading. A croc clip on the earth bar is not that test.
When you cannot reach it: if measuring the conductor is impractical, 8.6.3 allows suitability to be confirmed by an earth loop impedance test from the point of consumption under 8.6.5.1. A different test with a different number. Say which one you did on the sheet.
The limit is not about how good the copper is. It is the highest path resistance that still lets enough fault current flow to trip the breaker inside its disconnection time. A 6 A breaker trips on a small current, so the earth path may be comparatively poor. A 63 A breaker needs a lot of current in a hurry, so its earth path has to be far better.
That is also why the value means nothing on its own: pair it with the earth loop impedance test at the main switch (8.6.5.1), where the fault current must reach at least 3 times the rated current of the device up to 63 A.
Type the reading, pick the breaker, and the app flags it against Table 8.1 as you go, then builds the CoC test report around it. 34 fault entries, invoices and quotes offline, 8 setup guides with drawings, solar suite. One file, no signal needed.
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