Concentric objects share the same center or origin. Circles, disks, and spheres may be concentric; such concentric objects need not have the same radius.

Concentric cable is a cable type used in TN-C-S earthing systems where the combined neutral and earth core completely surrounds the live core(s). This minimises the risk of completely cutting through the combined neutral and earth without first completely cutting through the live cores.

See also: eccentric

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