PVC-Insulated, heat resisting 90C cables for switchgear and controlgear wiring

Table 1(b)

Reference Method of insulation		Correction Factor
		Number of Circuit or Multicore Cables
		2	3	4	5	6	7	8	9	10	12	14	16	18	20
Enclosed or bunched and clipped direct to a non-metallic surface		0.80	0.70	0.65	0.60	0.57	0.54	0.52	0.50	0.48	0.45	0.43	0.41	0.39	0.38
		0.80	0.70	0.65	0.60	0.57	0.54	0.52	0.50	0.48	0.45	0.43	0.41	0.39	0.38
Enclosed layer clipped to a non-metallic surface	Touching	0.85	0.79	0.75	0.73	0.72	0.72	0.71	0.70	-	-	-	-	-	-
Enclosed layer clipped to a non-metallic surface	Spaced¹	0.94	0.90	0.90	0.90	0.90	0.90	0.90	0.90	0.90	0.90	0.90	0.90	0.90	0.90
Single layer multicore on a perforated metal cable tray, vertical or horizontal	Touching	0.86	0.81	0.77	0.75	0.74	0.73	0.73	0.72	0.71	0.70	-	-	-	-
	Spaced^1,2	0.91	0.89	0.88	0.87	0.87	-	-	-	-	-	-	-	-	-
Single layer multicore on a perforated metal cable tray, touching	Horizontal	0.90	0.85	-	-	-	-	-	-	-	-	-	-	-	-
	Vertical	0.85	-	-	-	-	-	-	-	-	-	-	-	-	-
Single layer multicore touching on ladder supports		0.86	0.82	0.80	0.79	0.78	0.78	0.78	0.78	0.77	-	-	-	-	-

Note :

1.‘Spaced’means a clearance between adjacent at least one cables diameter(De).

Where the horizontal clearance between adjacent cables exceeds 2De, no correction factor need be applied.

2. Not applicable to Mineral Insulated Cables. Please refer to Table 4B2 of S7671 for the required correction factors.

3. For details, please refer to BS7671:2001 Table 4B1