Allowable Span (mm)		Insulation Thickness (ITmm)
		35		50		80		100
		Steel	Alum.	Steel	Alum.	Steel	Alum.	Steel	Alum.
	0.5	2250	2000	2600	2350	3400	3050	3950	3500
	0.7	2650	2350	3050	2750	4000	3350	4600	4100
	0.9	2950	2600	3400	3050	4400	3950	5100	4400
Combined Conductivity Wm2. 0C	P.U.	0.429		0.332		0.229		0.189

Design Criteria and conductivity