On this TT supply I have a measured Zdb (all parallel paths in place) of 154? and yet the measured Zs on the ring (using RCD setting on my Metrel) is consistently below 1?. Can anyone explain how that can be?[/wiki]
High Zdb low Zs
- Thread starter Podooser
- Start date
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Something seems amiss there, probably the meter.
What's the R1+R2 value for the circuit? This added to your Zdb should be similar to the Zs figure you get when measuring at the furthest point.
What's the R1+R2 value for the circuit? This added to your Zdb should be similar to the Zs figure you get when measuring at the furthest point.
I'd say you still have an appliance on the ring still connected when you do the Zs and it is providing a parallel path eg boiler (earth of boiler connected to water pipes, maybe main water pipe is metallic in ground so providing a path)
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He has a Zdb reading of 154ohms with all equipotential bonding in place (assuming that's what he means by all parallel paths in place).
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