[BITList] Earths

[FS]

Hugh,
What I've done in places where it was not feasible to drive rods was to 
lay out an earth mat created by running bare conductors in a mesh 
configuration and covering with earth or in trenches these earth zones 
then have to be tested by establishing an earth point about a 100 metres 
away and checking the ground impedance until a suitable regulation 
reading is obtained. That said can also remember when working in a open 
face Iron ore mine where the grade was 80% pure Iron but with vein's of 
silica running though it such that when a shovel backed over its 6.6Kv 
supply cable one would have to hop to the switching cubical to trip the 
circuit breaker as enough fault current would be unable to flow but if 
one walked to the circuit breaker then the risk of getting a leg either 
side of a silica vain and a few thousand volts though the bits that hurt 
was always present under fault conditions
frank

On 10/29/2010 5:59 PM, HUGH wrote:
> Frank,
> The soil depth in our area varies from zero to a couple of feet - 
> trees tend to have shallow roots and fall over in high winds.  Bare 
> rock abounds - it used to be moorland.  To get the requisite depth and 
> slope for sewers, etc, in front of our houses,  the local council must 
> have blasted or otherwise formed a trench.  The soil level of our back 
> garden was artificially created - I recall how it was before the 
> houses were built.  So, not much chance of driving in an earth rod 
> here.  They'd have to convince me the present arrangements are 
> actually, as opposed to notionally, dangerous.  Carried to an extreme, 
> this would mean our area can't have an electrical supply.
> Hugh.
>
>
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