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Is it my imagination or is this EICR a little odd?

Chris Pearson

Last week I had a look at a property which is up for auction, more as a matter of curiosity than a serious investment, but it is charming and if only I were 10 years younger!

The EICR was published today. It wasn't a drive-by (only at 70 mph mind 'cos there is a speed camera right beside the house on the M27) because the stickers, dated 2020 were on the DBs (peak and off-peak).

The estimated age of the installation is 35 years, but the DBs looked very modern - all RCBO and clean.

TN-C-S aerial supply. Ze was given as 0.31 Ω. So why in the table below do some of the Zs add up, and some not?

Circuit R1+R2 Zs R1+R2+Ze Discrepancy
Lights down 0.99 1.79 1.30 0.49
Lights up 1.86 2.36 2.17 0.19
Sockets down 1.42 2.02 1.73 0.29
Sockets up 0.66 1.32 0.97 0.35
Cooker 0.83 1.63 1.14 0.49
Immersion heater 1.12 1.46 1.43 0.06
Cooker 0.75 1.06 1.06 0.00
Shower 0.44 0.89 0.75 0.14
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  • Looking again, I think it's the R1+R2 numbers that worry me more ... why's the upstairs lighting almost twice that for downstairs? 1860 mΩ would imply over 50m of 1mm2 to the furthest point (about 24m further than downstairs). Likewise why downstairs sockets more than double upstairs?  - is there a very long spur out to an outbuilding or something or does it really have a 300m long ring?

       - Andy.

  • in reply to AJJewsbury
    AJJewsbury said:
    1860 mΩ would imply over 50m of 1mm2

    2-way switching can add a lot (e.g. landing light). Believe it or not, it's possible to get over 50 m cable distance in (R1+R2) from the furthest loop-in luminaire on a lighting circuit in a 32' x 10' transportable office unit.

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  • in reply to AJJewsbury
    AJJewsbury said:
    1860 mΩ would imply over 50m of 1mm2

    2-way switching can add a lot (e.g. landing light). Believe it or not, it's possible to get over 50 m cable distance in (R1+R2) from the furthest loop-in luminaire on a lighting circuit in a 32' x 10' transportable office unit.

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