UL 1666-2021 pdf free download.Test for Flame Propagation Height of Electrical and Optical-Fiber Cables Installed Vertically in Shafts.
4.7 Data acquisition equipment
4.7.1 A digital data acquisition system shall be used to collect and record the air inlet slot velocity and second floor slot thermocouple temperature at intervals of 5 seconds or less.
5 Specimen Conditioning
5.1 Prior to testing, all cable specimens are to be conditioned for a minimum of 24 h in a controlled environment of 73 i5F (23 ±3°C) and relative humidity of 50 ±5 percent. Samples which are supplied on reels shall have any wrapping materials removed before conditioning.
6 Determination of Specimen Diameter
6.1 Use either a diameter tape, vernier caliper, or a micrometer with an accuracy of 0.00 1 in (0.025 mm) to measure the specimen diameter.
6.2 The diameter tape is appropriate for specimens that are uniformly round. Ensure that the tape is wrapped tightly around the specimen, but not so tight that the specimen is compressed. Use an arithmetic average of three readings over a 1 ft (0.3 m) length of the specimen as the specimen diameter.
6.3 The vernier caliper is appropriate for all sizes of cable specimens, and is especially useful for small diameter cables which are not uniform in cross section.
6.4 If the specimen is round, close the caliper gently around the cable being careful not to compress it and take the reading. Repeat the measurement a minimum of five times over a length of 1 ft (0.3 m) of cable. The arithmetic average of the five readings is used as the diameter of the cable specimen,
6.5 If the specimen is not uniform in cross section, with the width to thickness ratio less than 2:1, take three measurements at the wide points, and three measurements at the narrow points of the specimen The diameter is an arithmetic average of the six readings.
6.6 If the width to thickness ratio of the specimen is greater than 2:1, then the width of the specimen is taken as the specimen diameter. Measure the width of the specimen at six locations on a 1 ft (0.3 m) length of the cable. The specimen diameter is an arithmetic average of the six readings.
6.7 The micrometer is appropriate for a cable specimen with a uniform cross section. Take five measurements of the specimen diameter over a 1 ft (0.3 m) length of the cable. The arithmetic average of the five readings is the diameter of the cable specimen.
7 Number of Cable Lengths
7.1 The number (N) of cable lengths (rounded to the next lower whole number) to be used in a given test is to be determined by means of the following formula.UL 1666 pdf download.