Q5 of 5 Cable Management Questions - How do I protect cables from damage when installing or entering an enclosure?
When cables are bent it is important that there is no undue strain on the internal conductors caused when the bend is too tight (522.8.3). Fig 2 shows an example of the recommended bending radius for 1.5 mm2 insulated and sheathed ‘twin and earth’ (Table D5 OSG).
Fig 3 Bending radius example - image courtesy of T.J. Bratley
Two issues must be addressed when cables enter an accessory: the risk of damage to the sheath/insulation at the point of entry, and any potential strain on connections.
Where a cable enters a metallic accessory box having no protection from sharp edges, there is a risk that the insulation surrounding conductors may become damaged leading to arc and shock risk. Where cables enter a metallic accessory box, it is important that protection is provided, such as with rubber grommets or similar.
Even where cables entering an accessory box or other metallic enclosure are protected from damage, terminations may still be impacted by strain as cables are left unsupported. In such circumstances it is necessary for suitable support to be provided and compression glands provided to ensure the electrical and mechanical strength of terminations (522.8.5 and Note).
Unicrimp brass meter tail glands
For more information, check out our SGTV episode on Cable Management Systems at https://youtu.be/9qdwKzCJm6Q