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Which RCD tests are actually requiredHalf, one, or five times?

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BS 7671 requires one times. Guidance Note 3 recommends half times and one times. Five times is optional.

BS 7671 only requires a test at one times (1×I∆n), with the instrument set to Type AC, and the result recorded on the Schedule of Test Results. Guidance Note 3 sets out two lists beside it.

TestExpected resultStatus
Half timesShould not tripRecommended · Table 2.18(a)
One timesTrip within 300 ms (non-delayed) · 500 ms (S-type)Recommended · Table 2.18(a) · the one BS 7671 requires
Five timesWithin 40 ms (non-delayed, 30 mA or less) · 150 ms (S-type)Optional · Table 2.18(b)

The one-times test is run at 0° and 180°, and the longer of the two times is recorded — in column 28 of the Schedule of Test Results. Older non-delay devices to BS 4293 or BS 7288:1990 have a 200 ms limit at one times.

Two lists, and they do different jobs. Guidance Note 3 · Table 2.18(a) · p.96 gives the recommended tests, with the instrument set to Type AC whatever type the RCD is. Table 2.18(b) · p.96 lists the optional ones: five times, the pulsed-DC tests for Types A, F and B, and the smooth-DC test for Type B. The optional tests are for fault-finding only, they are not BS 7671 requirements, and they shorten the RCD’s life. The RCD type markings are Figure 2.32 · p.97.
Doing it manually, you choose which tests to run. On auto it cycles six, because each is run at 0° and 180° — the sine wave icon on the display flips direction between them.
S type is the time-delayed one. The 40 ms five-times figure is for non-delayed devices; an S-type has 150 ms.

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