Discuss Zs ohms with maximum rcd ohms in the Electrician Courses : Electrical Quals area at ElectriciansForums.net
No this is just me wondering.im doing a eicr around the house and worrying about high zs readings looking for loose connections and I'm wondering why is the regulations even there to abide by.i can't think why it matters if the readings are over the maximum zs readings as theirs a rcd split load preotecting them .
I think I have probably misinterpreted your words, but the proximity of the 80% appears to refer to correcting a measured resistance to a 70°C resistance.The 80% factor is a good estimate of copper resistance at 70C when remeasured at 20C. So it's not a tolerance.
The BS7671 tabulated values will have the conductor temperature stated, and it's often 70C. We tend to test and measure when a circuit is at room temperature and so we multiply by 0.8 to get an equivalent value.
Thanks - that's what I meant to say... it is the 70°C resistance that is multiplied by 0.8 to give an value close to the expected measured resistance at 20°C...
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