Hi, any thoughts very welcome:
Domestic Electrical Installation Certificate from March 2004 (full re-wire by NICEIC approved contractor - previous owners) gives measured Zs as 106.6 ohms on TN-S Supply.
Explanation on cert given:
"High ohms on main cable sheath earth 106.6 ohms. All Zs readings high due to this: I have fitted an RCD 100A 100mA to the incomer to compensate"
Circuit Zs vary from 106.0 to 107.6 on the cert.
Have done basic confirmation with new Martindale EZ150 and this indicates earth loop in 10 - 100ohms range.
E-ON Central Networks website indicates 0.8 ohms typical max for TN-S, and I'm near to a town centre and on underground supply.
I assume the RCD on the incomer is to ensure disconnection times achieved, but should this be investigated further? Seems a bit like fixing the symptoms rather than the cause? Should I contact E-ON to see if there is an explanation or known issue in my street?
Thanks
Philip
Domestic Electrical Installation Certificate from March 2004 (full re-wire by NICEIC approved contractor - previous owners) gives measured Zs as 106.6 ohms on TN-S Supply.
Explanation on cert given:
"High ohms on main cable sheath earth 106.6 ohms. All Zs readings high due to this: I have fitted an RCD 100A 100mA to the incomer to compensate"
Circuit Zs vary from 106.0 to 107.6 on the cert.
Have done basic confirmation with new Martindale EZ150 and this indicates earth loop in 10 - 100ohms range.
E-ON Central Networks website indicates 0.8 ohms typical max for TN-S, and I'm near to a town centre and on underground supply.
I assume the RCD on the incomer is to ensure disconnection times achieved, but should this be investigated further? Seems a bit like fixing the symptoms rather than the cause? Should I contact E-ON to see if there is an explanation or known issue in my street?
Thanks
Philip