- If we’re are experience NCD when preforming an EICR on a property does this need to be noted on the observations, if so what code should this be given. I’m aware that this needs to be reported to the DNO and should be investigated and rectified.
NCD? (Neutral current diversion?)
What sector are you in, what earth arrangement do you have and I'd like to know how you found this and what made you look? Did you clamp the main earth and find current there? Not doubting, just interested.
Kind Regards
Tatty
Thanks for your response, I am an electrician that does residential, commercial & industrial works. In this instance I have a PME supply into a clients property, we recently received a bulletin post from SELECT which started about the increase in NCD and how we should proceed with works on a PME supply. Due to this I thought as a measure to check before starting works on the main earth with a clamp meter. With the installation isolated as we should expect there was no current but when load was increased such as a shower I was reading between 10 to 15A passing back through the main earth and finding a path to the transformer through the bonding ( gas & water)
With the installation isolated as we should expect there was no current
The typical situation is to have extraneous-conductive-parts in parallel with the supply CNE conductor ... so while for the most remote installation current is likely to from through the installation's load to N-PE link and then out via main bonding to supply pipework or shared structural steel, that same current will then find its way back to the star point via the bonding and then the supply CNE of another installation - so in many cases you could see significant currents whether or not loads in your own installation loads are connected or not. In some case (e.g. 3-phase distribution) your loads could well be out of phase with the current being "imported" via your pipework, so increasing your loads could appear to reduce the diverted currents!
- Andy.
With the installation isolated as we should expect there was no current
The typical situation is to have extraneous-conductive-parts in parallel with the supply CNE conductor ... so while for the most remote installation current is likely to from through the installation's load to N-PE link and then out via main bonding to supply pipework or shared structural steel, that same current will then find its way back to the star point via the bonding and then the supply CNE of another installation - so in many cases you could see significant currents whether or not loads in your own installation loads are connected or not. In some case (e.g. 3-phase distribution) your loads could well be out of phase with the current being "imported" via your pipework, so increasing your loads could appear to reduce the diverted currents!
- Andy.
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