Can you show your workings out and then we might be able to see were you are going wrong.
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For the spacing I would do 4 rows of 5 fittings spaced 10M apart in both directions and a 5M space between the last fitting and the outer wall.
That install looks a bit poor IMO. The cables appear to be just strung from point to point without much thought or even clips. Looking at it they mightn’t even be in the safe zones.
On mobile units you need to consider the vibration when moving. This generally means that you need to use a cable with fine flexible cores rather than solid cores.
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