[Mark]

I am trying to establish a good earth
for my old farm house in Spain. Unfortunatly the soil is only 12" deep
before I hit solid rock. I have a 24" long drill so I drilled two 10mm
holes about a foot apart into the rock, cut my 4 foot, 10mm copper
earthing rod in half, sunk the two halfs into the two holes, clamped
on my earth wire to each, and covered over with watery cement. The
question is, is this a good enough earth. I tried running a 40W light
bulb between my earth and live, and although the bulb lights, it is
getting 30 volts less than if I wired the bulb across the live and
neutral, ie 170V instead of 200V. Anybody give me some help please.

[email protected] (remove the X to reply)

 

[SQLit]

I am trying to establish a good earth
for my old farm house in Spain. Unfortunatly the soil is only 12" deep
before I hit solid rock. I have a 24" long drill so I drilled two 10mm
holes about a foot apart into the rock, cut my 4 foot, 10mm copper
earthing rod in half, sunk the two halfs into the two holes, clamped
on my earth wire to each, and covered over with watery cement. The
question is, is this a good enough earth. I tried running a 40W light
bulb between my earth and live, and although the bulb lights, it is
getting 30 volts less than if I wired the bulb across the live and
neutral, ie 170V instead of 200V. Anybody give me some help please.

[email protected] (remove the X to reply)

I do NOT KNOW about Spain for grounding. I have run into rock below the
surface several times. The National Electric Code allows for you to install
the rod horizontally if needed. Cutting the rod in half is not the answer.
Depth is the biggest part of a grounding system. Second comes mass.
I suggest you replace your 2 foot rods with 2- 4 foot rods horizontally as
deep as it is practical, separate them by at least 6 feet in any direction.
If you have a planter that gets watered regularly even better. Here in the
USA we use 8 or 10 feet long ground rods. I have installed 20 foot chemical
ground rods for sensitive installations. Something you probably do not need.
Second method is to dig 3 holes as deep as you can and use a 24 inch 1/4 in
thick with a #4 brazed on to the steel using silver solder. Separate these
plates/holes by at least 10 feet. It is called a counter poise. Depending on
the soil conditions this method may not last as long as a copper clad ground
rod. It will last over 5 years even in very aggressive soils.

Your description indicates that Spain is 220v or 240v single phase like
France or Britton.
How do you get your water? Is the piping metal? Do you have gas? Is it
metal? If so then make sure your bonding these as well at your service. Just
get a pipe grounding clamp and run the #4 bare through the clamps until you
have every electrically connected.

Please note I am suggesting #4 because that is what I use. It is the
smallest wire I feel safe not installing in conduit. Might be a good time
to check with the locals,
Good luck, some day maybe I will get to see Spain.

 

[Harry Bloomfield]

Mark wrote on 08/02/2004 :-

I am trying to establish a good earth
for my old farm house in Spain. Unfortunatly the soil is only 12" deep
before I hit solid rock. I have a 24" long drill so I drilled two 10mm
holes about a foot apart into the rock, cut my 4 foot, 10mm copper
earthing rod in half, sunk the two halfs into the two holes, clamped
on my earth wire to each, and covered over with watery cement. The
question is, is this a good enough earth. I tried running a 40W light
bulb between my earth and live, and although the bulb lights, it is
getting 30 volts less than if I wired the bulb across the live and
neutral, ie 170V instead of 200V. Anybody give me some help please.

[email protected] (remove the X to reply)

That does not sound to be much good....

I would suggest drilling holes will of been of little use, but it
depends upon the type of substrata. A better way would be to lay the
rods horizontally.

If it is permitted and practical, you might try running out several
bare copper wires in a star pattern from your earthing connection, then
going along with a spade to cut a slot to push them into. Solid copper
will be better than stranded for this purpose.

--
Regards,
Harry (M1BYT)...

Remove the 'NOSPAM' in my email address to reply.

Free Amateur Radio Courses:-
http://www.ukradioamateur.org

 

[sQuick]

I am trying to establish a good earth
for my old farm house in Spain. Unfortunatly the soil is only 12" deep
before I hit solid rock. I have a 24" long drill so I drilled two 10mm
holes about a foot apart into the rock, cut my 4 foot, 10mm copper
earthing rod in half, sunk the two halfs into the two holes, clamped
on my earth wire to each, and covered over with watery cement. The
question is, is this a good enough earth. I tried running a 40W light
bulb between my earth and live, and although the bulb lights, it is
getting 30 volts less than if I wired the bulb across the live and
neutral, ie 170V instead of 200V. Anybody give me some help please.

[email protected] (remove the X to reply)

take a look at PME or TNCS

Squick..

 

[Peter K]

I am trying to establish a good earth
for my old farm house in Spain. Unfortunatly the soil is only 12" deep
before I hit solid rock. I have a 24" long drill so I drilled two 10mm
holes about a foot apart into the rock, cut my 4 foot, 10mm copper
earthing rod in half, sunk the two halfs into the two holes, clamped
on my earth wire to each, and covered over with watery cement. The
question is, is this a good enough earth. I tried running a 40W light
bulb between my earth and live, and although the bulb lights, it is
getting 30 volts less than if I wired the bulb across the live and
neutral, ie 170V instead of 200V. Anybody give me some help please.

[email protected] (remove the X to reply)

I believe that an effective method of reducing the resistance between earth
rods and the rock is to fill the "voids" with bentonite ( AKA Fuller's Earth
and cat litter). Bentonite retains moisture and therefore should remain
conductive under dry conditions. I presume you would add it dry and then
"water" it in. Bentonite is used in drilling muds so if 10mm x 24" is no
use then 300mm x 1000m ? ;-)

 

[Airy R Swipe]

take a look at PME or TNCS

Do they have those systems in Spain?

 

[Don Kelly]

I am trying to establish a good earth
for my old farm house in Spain. Unfortunatly the soil is only 12" deep
before I hit solid rock. I have a 24" long drill so I drilled two 10mm
holes about a foot apart into the rock, cut my 4 foot, 10mm copper
earthing rod in half, sunk the two halfs into the two holes, clamped
on my earth wire to each, and covered over with watery cement. The
question is, is this a good enough earth. I tried running a 40W light
bulb between my earth and live, and although the bulb lights, it is
getting 30 volts less than if I wired the bulb across the live and
neutral, ie 170V instead of 200V. Anybody give me some help please.

[email protected] (remove the X to reply)

 

[Mark]

I am trying to establish a good earth
for my old farm house in Spain. Unfortunatly the soil is only 12" deep
before I hit solid rock. I have a 24" long drill so I drilled two 10mm
holes about a foot apart into the rock, cut my 4 foot, 10mm copper
earthing rod in half, sunk the two halfs into the two holes, clamped
on my earth wire to each, and covered over with watery cement. The
question is, is this a good enough earth. I tried running a 40W light
bulb between my earth and live, and although the bulb lights, it is
getting 30 volts less than if I wired the bulb across the live and
neutral, ie 170V instead of 200V. Anybody give me some help please.

[email protected] (remove the X to reply)

Just to add a bit more detail. I have no open ground, the only access
I have, is to the front drive which is concreted over (so no natural
watering). I can bore holes OK, but breaking up the whole drive, to
start laying out star patterns is a tad tricky. I surely cannot be the
only soul to have this problem. If I do not get a better suggestion,
this weekend I will try another rod, buried at 30 degrees into the
ground. Not being a fully fledged electrician, pray tell me what test
I do, to know that I have reached the required criteria??

 

[Harry Bloomfield]

Just to add a bit more detail. I have no open ground, the only access
I have, is to the front drive which is concreted over (so no natural
watering). I can bore holes OK, but breaking up the whole drive, to
start laying out star patterns is a tad tricky. I surely cannot be the
only soul to have this problem. If I do not get a better suggestion,
this weekend I will try another rod, buried at 30 degrees into the
ground. Not being a fully fledged electrician, pray tell me what test
I do, to know that I have reached the required criteria??

Not my area of expertise, or my country, but I would suggest an 'earth
loop impedence tester' be used. Even then you would need to know the
local regulations (or code) for the type of installation you have, to
be able to determin what would be a satisfactory reading on the above
instrument.

Is there perhaps a Spanish electrical engineering newsgroup who might
be able to offer proper and accurate local advice on this?

 

[Corinna Prakash]

Not my area of expertise, or my country

Or even your planet, Harry. Why not STFU?

 

[Louis Bybee]

Mark <[email protected] (Do not use)> wrote in message

You're hardly the first person with this problem. The local
professionals will no doubt have a solution. Could be as simple as a
longer drill bit

Apart from the risk that you are doing something you aren't allowed to
without a license, you need to check what the local regulations have
to say. Is this a TT or TN-C(-S) or perhaps even a TN-S service? In
the latter two cases, you don't really need the rods at all. In the
case of a TT system, you can choose an RCD rating such that the
present earth resistance is acceptable. (If you want to convert to a
TN system, you need to check with the utility to see if they allow you
to use the neutral as earth.)

If you are unsure about what you are doing, call a pro.

/Clas-Henrik

For the benefit of those of us across the big pond would you describe the
services you refer to above. I am unfamiliar with the acronyms used.

Thank you.

Louis--
*********************************************
Remove the two fish in address to respond

 

[sQuick]

For the benefit of those of us across the big pond would you describe the
services you refer to above. I am unfamiliar with the acronyms used.

Thank you.

Louis--

TT (Terra/Terra)- earth return path via the ground, ie earth rod at the
transformer and earth rod at the consumers supply box.

TN-S(Terra/Neutral Separate) - An earth cable is supplied to the
consumers box fromthe supply company(sometimes this is the
supply cable sheath etc)

TN-C-S(Terra/Neutral Combined-Separated) - (also called PME) The
earth and Neutral are joined at the consumers supply point, but
separate through the whole installation.

RCD(Residual Current Device) - same as a gfci.

Hope this makes some sense.

sQuick..

 

[Louis Bybee]

TT (Terra/Terra)- earth return path via the ground, ie earth rod at the
transformer and earth rod at the consumers supply box.

TN-S(Terra/Neutral Separate) - An earth cable is supplied to the
consumers box fromthe supply company(sometimes this is the
supply cable sheath etc)

TN-C-S(Terra/Neutral Combined-Separated) - (also called PME) The
earth and Neutral are joined at the consumers supply point, but
separate through the whole installation.

RCD(Residual Current Device) - same as a gfci.

Hope this makes some sense.

sQuick..

Thank you for the definitions.

How common is the TT (Terra/Terra) service in Europe? I'm making the
assumption that the loads are all phase to phase with this type of service,
and no loads are phase to Neutral, or Earth? This type of service scares me
even if there aren't any phase to Neutral or Earth loads.

Louis--
*********************************************
Remove the two fish in address to respond

 

[sQuick]

Thank you for the definitions.

How common is the TT (Terra/Terra) service in Europe? I'm making the
assumption that the loads are all phase to phase with this type of service,
and no loads are phase to Neutral, or Earth? This type of service scares me
even if there aren't any phase to Neutral or Earth loads.

Louis--

dunno about rest of europe, but TT systems are quite common
in rural areas of the UK.

Most loads will be phase to neutral as only comercial/industrial
installations use 3 phase(with a few exceptions).

UK uses 230 phase to neutral, not 230 centre tap neutral.
I believe this to be the same for most of europe,

heres a good pdf on the subject
http://www2.schneider.co.uk/seweb2/internet/catalogues.nsf/luAllByID/JPAE-5FCG2D/$file/D.pdf

sQuick..