Split con submain

[pc1966]

I think the consensus is that even though it’s not technically in the regs, there nothing unsafe about using it.
However, it’s got no more protection than a twin and earth. Would you run a 16mm twin and earth underneath plaster outside of a safe zone with just the dno fuse for protection?

In terms of stopping a drill then no, copper is not as tough as steel. But really would SWA armour stop a battery drill with HSS bit? I doubt it.

What SWA has is an earthed shield that makes sure if you do penetrate the cable then it shorts it out, so you don't have the risk of a live screw, walls support, etc, going unnoticed until it causes a fatal shock some day. That is the reason for the 30mA RCD with cable not buried more than 50mm behind walls, etc. Same idea for the likes of Flexishield.

Split concentric though is an odd one to consider. The construction means you can't reach the line conductor without going through either (or both) the CPC or neutral. So in that sense it is as safe as SWA in terms of ADS under such an accident condition.

But...you might be in contact with neutral after a minor accident, and technically that is "live" (as in current carrying), so you should have it disconnected under fault conditions. But RCBOs are (in the majority) only disconnecting the line, and don't switch neutral. So if split-con cable is unsafe due to the risk of exposed neutral under failure/fault conditions, how can SP RCBOs be considered safe?

Ladies and gentlemen, discuss!

 

[westward10]

Split concentric during the 16th Ed reign was deemed to be one of the cables which could be buried in a wall without additional rcd protection, this was later removed.