BS EN 16165 Annex C — The Pool Pendulum Standard

Why the standard changed

The European Committee for Standardization (CEN) consolidated four existing national slip-test standards into a single European standard, BS EN 16165:2021, published in December 2021 and adopted across the UK in February 2022. The four methods previously published separately are now annexes of the single standard, with the pendulum test as Annex C.

For UK pool operators, this changed the standard reference but not the test. A pendulum test under BS EN 16165 Annex C is the same physical test as under BS 7976-2.

The UK National Foreword — important for pools

The UK National Foreword to BS EN 16165 contains a significant statement: the pendulum (Annex C) is considered the only one of the methods in the standard that should be relied on to correctly assess pedestrian slip risk in wet conditions. This reflects the UK's four decades of forensic experience with the pendulum.

For pool operators, this matters because pool environments are by definition wet, persistently. Annex C is therefore the method UK courts, insurers and HSE refer to for pool slip-risk assessment.

Equipment specified

The Annex C pendulum is the TRL-pattern (Transport Research Laboratory) pendulum tester, also known as the British Pendulum, the Stanley pendulum or the Munro pendulum (different manufacturers produce instruments to the same specification). The instrument comprises:

• A weighted arm pivoted on a horizontal axis
• A rubber slider mounted at the foot of the arm (Slider 55, 57 or 96 depending on environment)
• A graduated scale indicating residual swing
• A levelling and height-adjustment system to set the slider correctly above the test surface

Calibration requirements

Annex C specifies pre-test calibration including:

• Friction-disc check — a reference disc producing a known PTV reading
• Slider conditioning — abrading the slider edge to standard roughness on prescribed paper
• Slider sweep distance verification
• Instrument level (in two axes)
• Slider release height

For pool environments, the levelling step is non-trivial: pool surrounds often have falls toward drains, and the pendulum must be levelled at every test point to produce valid readings.

Test procedure

1. Surface preparation — remove loose contamination; for pool surrounds the surface is wetted with clean tap water at ambient temperature
2. Slider conditioning — abrade the slider edge to standard roughness on prescribed paper
3. Practice swings — release the pendulum to allow the slider to settle
4. Recorded swings — typically five swings per direction, results averaged
5. Re-conditioning between sets — slider edge re-conditioned before the next set
6. Three directions of test — typically front-back, left-right, and a diagonal

Reporting requirements for pools

Compliant Annex C reports for pools include: identification of the surround tested; the slider used (Slider 55 for barefoot, with any Slider 57 or 96 zones noted separately); contamination state; calibration record; individual swing results per direction; and calculated mean PTV per location. UKAS-accredited reporting goes further, including methodology declarations, equipment serial numbers, traceability statements and the technical signatory.

If your pool spec still references BS 7976-2

The pendulum test you receive under BS EN 16165 Annex C is, in technical terms, the same test as under BS 7976-2. Pool specifications and contracts that still reference BS 7976-2 by name are typically satisfied by Annex C testing. New specifications and refurbishment scopes should reference BS EN 16165:2021 directly.