EN 50266 specifies methods of test for the assessment of vertical flame spread of vertically-mounted bunched wires or cables, electrical or optical, under defined conditions. The test is intended for type approval testing. The requirements for the selection of cables for testing are given in annex A. The flame spread is measured as the extent of damage of the cable sample. This procedure may be used to demonstrate the cable's ability to limit flame spread. This Part 2-1 covers Category A F/R and relates only to power cables of conductor cross-sectional area greater than 35 mm2 installed on the test ladder in a spaced configuration on the front and rear to achieve a nominal total volume of non-metallic material of 7 litres per metre of test samples. The flame application time is 40 min. This method of mounting is intended for special cable designs used in particular installations when required in the cable specification. Category A F/R is not intended for general use. A recommended perf