In addition, IEC332-3 has A regulation, namely when making class A test, if the sample in between Every other arrangement (there is a core of conductor is greater than 35 was occasion) in front of the standard ladder arrangement not bottom, Power Cable can be arranged at the back, and expressed in AF/R.Or use wide type of ladder (0.8 m wide) all rows in front of the ladder (AF), and with double burner for the fire.But if large size in the standard cable ladder front row, with a single burner for the fire, still write for AF.

To simplify the model, for this kind of situation both for ZA. According to the standard GB 12666.6 90, refractory divided into class A and class B two levels.The offering of class A fire temperature is 950 ℃ ~ 1000 ℃, B type for the fire temperature is 750 ℃ ~ 800 ℃.Had earlier expressed in NH type fire resistant cable, according to the requirements of IEC 331-331 standard, equivalent to the standard of class B.Because some users require A kind of fire-resistant wire and cable, so the expanded model for Flexible Cable NA and NB, to show the difference.But, in a recent new standard IEC60331-1999, published by IEC for fire temperature is 750 c ~ 750 ℃, and the Suggestions for the improvement of test temperature is still under consideration.As A result, such as equivalent to the preparation of the new national standard, the fire resistance rating is not A class B class distinction.The fire-resistant wire and cable model can be simplified as team if IEC separate category to the test temperature again in the future, we have room for the development of models.