Cable Clamp Spacing Formula

[Power0020]

I came across cable manufacturer design report quoting a formula to calculate the required clamp spacing, however, no reference is mentioned for the formula.

Dynamic Force:

Clamp Spacing:

Where can I find the reference standard/publication for this formula?

 

[cuky2000]

The formula for determine the forces between two parallel conductos is based on the Lorentz Force Law used to calculate the electromechanical force between two conductors, as follows:
F = μ₀ * i₁ * i₂ / 2π.s
Where:
F = Force between conductors
μ₀ = Magnetic permeability constant
i₁ = Instantaneous current in conductor #1
i₂ = Instantaneous current in conductor #2
π = pi =(3.1416...)
s = Spacing between conductor centers
Since the Lorentz Force Law only considers two conductors, basic mathematical techniques may be utilized to solve for three or more conductor.

A reference can be found on the IEC Std 61914 – CABLE CLEATS & SHORT CIRCUIT PROTECTION CALCULATIONS.
Should be noted that in the USA, the NEC and IEEE Std have brief references associated with cable cleats but is not many details.
Regarding the cable spacing, cable cleats manufacturer suggest the separation of the cable support considering the forces test rating of their product. One example of cable support and separation is shown below.

 

[7anoter4]

Formula for Fs is well known for three-phase short-circuit force -see for instance IEC 60865-1[2]
The restriction of a= b*Da it is-in my opinion- the Manufacturer requirement as the clamp withstand maximum force so [as force limiting].
You cannot apply this for equilateral triangle-without any space between-single core cables[where b=1].