On 09/12/2017 12:46, wrote:
On Thursday, 7 December 2017 13:35:22 UTC, John Rumm wrote:
On 07/12/2017 11:20, SL wrote:

ISTM that a person who does not know that neutral and earth MUST
be connected together in at least one place is a person who is
not qualified to do such work and the resulting installation is
at risk of being in breach of the Building Regulations. See

Erroneous statement followed by a non sequitur... Mmmm useful ;-)

It is a requirement that the
local neutral wires must, somehow, be electrically connected to the
terrestrial Earth, and it is a requirement that the local earth wires
must, somehow, be electrically connected to the terrestrial Earth.

That is a somewhat different statement from "neutral and earth MUST
be connected together in at least one place". Even then its still
questionable. With a TT supply[1] its fair to assume the neutral will be
connected to earth at the transformer. However that may be the only
place, and there may be no direct connection to the neutral to the
customer's earth.

Their earth should be independently connected to earth locally, however
that may show hundreds of ohms resistance to the earth point on the
supply and hence to the neutral at entry to the premises. (and that
obviously ignores things like IT setups with gensets etc).

[1] Yes, I know the OP does not have one of these, but you made a
blanket statement without qualification.

Therefore the reported connectivity is required to exist, and so

Low impedance connectivity as described by the OP is not *required* to
exist (since it may not be possible), and on TT installs may not.

should be expected; it occurs due to at least one connection,
somewhere; such a connection may be man-made metallic or by way of
the terrestrial Earth (or by any other reliable means, if any is
possible).

Indeed, and that is different from what you said previously.

I also took issue with the assertion that someone not intimately
familiar with earthing systems would not be "qualified" to work on an
electrical system. I have met a number of professionally qualified
electricians that only have a tenuous grasp on such things, but they can
still produce good quality work by applying the rules as specified.

I would assert that its perfectly possible to do a safe and compliant
extension to a socket circuit, and know nothing at all about earthing
systems beyond the need to connect the wires to the socket and test the
continuity when done (as I did many times when I was 12, and would not
have known my earth loop impedance from my elbow!)

The final "at risk of being in breach of the Building Regulations" was a
rather mealy mouthed straw man IMHO. One could argue that everyone is
"at risk" of being in breach of one building regulation or another, but
there was nothing in the OPs post to suggest that was likely here - the
fact that he was asking questions about his observations that obviously
resulted from testing his installation should offer reassurance that
improper work would be much less likely rather than more.

(here endeth the rant about people offering unhelpful criticism in place
of useful advice)


--
Cheers,

John.

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