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Connecting different sized cables

Connecting different sized cables

Connecting different sized cables

Just wondering how everyone would connect a 120mm2 2C+E cable (Cable 1) to a 16mm2 cable 2C+E(Cable 2). Cable 1 is from the switchroom (upstream CB is 32A) to a remote room (very long run I have been told) and is 120mm2 for volt drop. Both cables are copper. Once Cable 1 enters the remote room, it needs to connect to Cable 2 to power a cabinet, with loads of 16A or less. I was thinking of a junction box with an isolator or something along those lines? How does everyone usually connect cables that are so different in size?

RE: Connecting different sized cables

Terminal box with stud or busbar feedthrough terminals? Resin joint with bolted lugs?

RE: Connecting different sized cables

Isn't it a requirement that if changing cable sizes it has to be done via some downstream protective device(fuse, breaker) is downstream cable is smaller CSA than upstream.

RE: Connecting different sized cables

that depends upon whether the upstream protective device is sized to protect the smaller cross section cable, which is entirely possible if the larger cable is only oversized for volt-drop rather than for loading. In this case I would say that a 32A breaker protects both cables from a thermal perspective, but it is indeterminate from the information provided whether or not that breaker is adequate to meet disconnect times for short-circuit and earth fault.

RE: Connecting different sized cables

Or it might fall under a tap rule.

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