On 26/12/2017 23:44, Iggy wrote:
replying to John Rumm, Iggy wrote:
You know it would be very much easier to follow your posts if you could
quote selectively.
(that daft web site you use, does let you quote - just select the text
of the message you are replying to before you start entering your
response and it will quote the source material)
1 - I didn't go off on any tangent.
You seem to think Earthing is only ever a
1-way road and here you are telling people that I'm talking gibberish by
saying some appliances are Earthed, just to then confirm and tell me
they're Earthed...I know, I said it. You saying it to tell me I'm wrong is absurd.
That's how and why they get fried in a flawed Earthing setup.
I was pointing out to you that what you claimed the additional earth
electrode could do (i.e. that it could bring a potential from outside
the building into it) was already being done.
Hence the additional electrode makes no difference.
2 - Like I said, if you aren't adding a 2nd rod and connection you aren't
supplying an inlet and are only supplying an outlet. However, by
breaching the building's natural insulation from what's going on outside, you now draw
and bring the outside in to create instead of avoid the hazard.
ISTM that you don't understand how main equipotential bonding is used
and configured in UK electrical systems.
There is a summary he
http://wiki.diyfaq.org.uk/index.php/...ng_and_Bonding
3 - Yes, adding another connection to the wiring system will effect
everything attached to it, because you're providing an in and out loop for the
energy to travel. Plumbing isn't providing any electrical source and is Earthed by
itself being in the Earth. Again, no inlet provided and only an outlet.
Something connected to earth *is* a source of electrical potential.
Also, due to the presence of main equipotential bonds like those which
connects the water supply pipework to the main earthing terminal and
hence to the earth electrode in a TT system, there is already an
internal earth connection.
4 - Yes, this is what he has, in parallel or ONLY connected to each
other with just 1-connection. This, is extremely different than having multiple
connections to multiple rods...a proven disaster.
Connections to multiple earth electrodes may be made by a single
unbroken conductor which loops to each in turn, or via individual
dedicated conductors. Both are acceptable.
5 - Sorry, I misunderstood.
You misunderstood what?
6 - Not where I'm from.
Where are you from exactly? It does have a significant relevance if its
not the UK, since wiring practices and codes vary significantly around
the world. Advice based on what is say common practice in the US would
be of little relevance to the UK for example.
Never ever should an electrical wiring system or
structure protection system be connected to a lightning protection system.
That explicitly contradicts the requirements specified in BS 7430 "Code
of practice for earthing of electrical installations".
I quote verbatim:
"6.4 Protective equipotential bonding
NOTE 1 The protective measure automatic disconnection of supply, requires:
a) automatic disconnection in the event of a fault to earth;
b) protective earthing (to facilitate this); and
c) protective equipotential bonding to reduce touch voltages.
Where the automatic disconnection of supply is adopted, protective
equipotential bonding is recommended (see Figure 6), whatever the type
of supply system. Bonding, by means of main equipotential bonding
conductors, of extraneous-conductive-parts to the main earthing terminal
of the installation is recommended; these extraneous-conductive-parts
include:
a) water installation pipes;
b) gas installation pipes;
c) other installation pipework and ducting;
d) central heating and air conditioning systems;
e) exposed metallic structural parts of the building structure; and
f) other metallic parts such as cable trays and cable ladder racks.
Connection of a lightning protection system to the protective
equipotential bonding should be made in accordance with BS EN 62305-4.
#### my emphasis:
NOTE 2 BS EN 62305-4 requires that a bond is made between the lightning
protecting system and the installation equipotential bonding system. The
responsibility for specifying and installing this bond is that of the
organization responsible for the lightning protection system.
####"
(not that for completeness, lighting protection systems are very rarely
installed for domestic properties in the UK)
They are to be separate and even distanced from each other to avoid sharing
lightning's charge. I saw nothing to the contrary in your document, they
make it very clear that the lightning system shall have its own separated and
dedicated Earthing rods.
They have separate electrodes, however the are also bonded together.
This helps mitigate shock risk in the event of a strike by ensuring that
all accessible conductive paths will be elevated to the same (or
similar) electrical potential.
7 - See - 5.6.1 - What is protective multiple earthing? at
https://www.tlc-direct.co.uk/Book/5.6.1.htm this very clearly restricts the
use to the Utility Supplier and the last 2 sentences lock it out of
public use.
Most new UK supply installations are PME (TN-C-S) (Older properties
tended to more commonly be TN-S).
Significantly fewer properties use TT Earthing (i.e have to supply their
own earthing system - typically via earth rods etc[2])
So PME is widely installed for public use. The limitations spelt out at
the end of the page you cited (i.e. "The difficulty of ensuring that
bonding requirements are met on construction sites means that PME
supplies must not be used. Electricity Supply Regulations forbid the use
of PME supplies to feed caravans and caravan sites.") does not really
have any bearing on the current discussion, however there is a fuller
explanation here if you are interested:
http://wiki.diyfaq.org.uk/index.php/...rting_an_earth
Explanation of the general earthing terms he
http://wiki.diyfaq.org.uk/index.php/Earthing_Types
[2]
http://wiki.diyfaq.org.uk/index.php/TT_Earthing
8 - I've said my piece, you may have the last word.
For the avoidance of doubt, I am not picking on you are arguing for the
sake of it, it is just that the advice you are offering does seem to be
at odds with standard wiring practices here in the UK. I accept that
things are done differently elsewhere.
--
Cheers,
John.
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