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Posted By Topic: Existing domestic power circuits run in 1mm TPS

Feb 04 2019 09:25

I'm working on a property where all the existing wiring has been done in 1mm TPS. This includes the power circuits. Part of my works is relocating the switchboard. Do I have to replace the power circuit wiring or just de-rate the circuits to 8A?

Feb 04 2019 09:37

This sounds suspiciously as though it was installed by a non-licensed person. I'd proceed very cautiously and push for a rewire.

Feb 04 2019 15:58

ESR 113 says an existing installation is only allowed to remain in service provided it complied when installed, still complies with whatever the requirements were when it was installed, and also it has not become electrically unsafe.

Since there have always been requirements around overcurrent protection of conductors, I suspect this one never complied.
In which case it is quite simply NOT allowed to remain in service.

So the very least that has to happen is de-rating.


Feb 04 2019 18:30

and yet, there is very few instances where 1.5 is permitted for use for socket outlets.

Feb 04 2019 20:59

Is the conductor size definitely 1.0mm2? I have come across solid core conductors on power circuits before that almost caught me out. The size was actually 1.5mm2.

Feb 04 2019 21:11

Good point. Or, 1/.064 which is around 2mm²

Feb 05 2019 11:40

Someone else mentioned to me that it could possibly be solid core 1.5mm. I will have a closer look when I return to site. I'm hoping this is the case as it will make my life much easier than having to rewire the existing power circuits. All cables run through the roof space that has zero access.
Thanks for your help I'll let you know what I find.

Feb 15 2019 09:42

Yeah turns out it was solid core 1.5mm TPS so it wasn't as bad as I had previously though.