Installation in air

According to IEC 60287-2-1 for a single group of cables and IEC 60287-2-2 for more than one group of cables.

The wall clearance $e_{wall}$ is the distance between the closest cable to the wall and the object clearance $e_{hor}$ and $e_{ver}$ is the horizontal and vertical distance between two objects. Both values are relative to the outer diameter of the object.

There are discrepancies between the two standards IEC 60287-2-1 and -2-2, we use -2-1 when possible:

For one object near a wall, the -2-1 considers the object free from wall at a clearance factor of 0.3 whereas the -2-2 considers the factor 0.5 and mentiones this to be valid also for a surface below the object.
For two objects spaced horizontally, the standard -2-1 considers the objects spaced at a clearance factor of 0.75 whereas the -2-2 considers the factor 0.5.
For two and three objects spaced vertically, the standard -2-1 considers the objects spaced at a clearance factor of 1 whereas the -2-2 considers the factor 0.5 plus an equation (refer to $h_{lg}$) between 0.5 and 4.

Symbol

$inst_{air}$

Related

$F_m$

Radiation coefficient mutual

$h_{bs}$

Heat dissipation coefficient for black surfaces in free air [W/m$^2$/K$^{5/4}$]

$K_{cv}$

Convection factor

Choices

Id	Installation	factor Z	factor E	factor g	wall clearance	object clearance	Info
1	1 single object	0.21	3.94	0.6	0.3	0	Installation on non-continuous brackets, ladder supports or cleats, clearance to wall ≥ 0.3⋅D
2	2 objects touching, horizontal	0.29	2.35	0.5	0.5	0	Installation on non-continuous brackets, ladder supports or cleats, clearance to wall ≥ 0.5⋅D
3	2 objects spaced, horizontal	0.21	3.94	0.6	0.5	0.75	Installation on non-continuous brackets, ladder supports or cleats, clearance to wall ≥ 0.5⋅D, horizontal clearance 0.75⋅D
4	2 objects touching, vertical	1.42	0.86	0.25	0.5	0	Installation on non-continuous brackets, ladder supports or cleats, clearance to wall ≥ 0.5⋅D
5	2 objects spaced, vertical	0.75	2.8	0.3	0.5	1.0	Installation on non-continuous brackets, ladder supports or cleats, clearance to wall ≥ 0.5⋅D, vertical clearance D
6	3 objects touching, horizontal	0.62	1.95	0.25	0.5	0	Installation on non-continuous brackets, ladder supports or cleats, clearance to wall ≥ 0.5⋅D
7	3 objects spaced, horizontal	0.21	3.94	0.6	0.5	0.75	Installation on non-continuous brackets, ladder supports or cleats, clearance to wall ≥ 0.5⋅D, horizontal clearance 0.75⋅D
8	3 objects touching, vertical	1.61	0.42	0.2	1.0	0	Installation on non-continuous brackets, ladder supports or cleats, clearance to wall ≥ D
9	3 objects spaced, vertical	1.31	2.0	0.2	0.5	1.0	Installation on non-continuous brackets, ladder supports or cleats, clearance to wall ≥ 0.5⋅D, vertical clearance D
10	3 objects touching trefoil	0.96	1.25	0.2	0.5	0	Installation on non-continuous brackets, ladder supports or cleats, clearance to wall ≥ 0.5⋅D
11	1 single object on wall	1.69	0.63	0.25	0	0	Clipped direct to a vertical wall, D ≤ 0.08 m
12	3 objects in trefoil on wall	0.94	0.79	0.2	0	0	Clipped direct to a vertical wall, D ≤ 0.08 m
13	More than one group of cables	0.96	1.25	0.2	-	-	The arrangement of more than one group of cables is limited to configurations in IEC 60287-2-2
14	More than one multi-core cable	0.21	3.94	0.6	-	-	The arrangement of more than one multi-core cable is limited to configurations in IEC 60287-2-2

Image

IEC standard 60287-2-1 Ed. 2.0 (2015) Table 2