Martin Angove wrote:

[OSG note (i) to Figs, 4a, 4b & 4c]

It is *probably* meant to guard against the situation where the
connection to the first service becomes loose.

I'd suggest it is meant to maintain the bonding to the other services in
the event that the clamp to an intermediate service is removed
(temporarily or permanently) in connection with work being done on that
service. E.g. if a metal service pipe is replaced in plastic the clamp
can be removed safely and continuity is maintained without the need for
any electrical knowledge by the plumber/gasfitter etc. The plumber
(etc.) would have to deliberately cut the wire to disrupt the bonding.

I don't see that this in any way forbids the use of a properly-made
in-line joint in a bonding conductor. In any case the main bonding
conductor(s) have to be disconnectable from the main earth terminal for
test purposes - so there's one joint to start with...

Having said that, I have always run single continuous lengths for the
main bond, and have never jointed. I would consider a joint where
replacing the whole run would be impractical, but impractical does not
include "the run is 15m and I've only 12m of cable left on the drum".

I agree, but there's nothing in section 543-03 of BS 7671 -
"Preservation of electrical continuity of protective conductors" that
specifically bans such joints. There are only 6 regulations in this group:

543-03-01 requires suitable protection against mechanical and chemical
deterioration, and electrodynamic effects;

543-03-02 requires separate protective conductors (PCs) up to and
including 6mm^2 to be insulated and requires sleeving of the bare PC of
a multi-core cable (e.g. T&E) at terminations;

543-03-03 requires connections to comply with the accessibility
requirements of section 526-04 (i.e. as for live conductors). Joints in
metal conduit or trunking systems used as PCs are excluded from this;

543-03-04 forbids the use of switching devices in PCs (with certain
exceptions). It also says "Joints which can be disconnected for test
purposes are permitted in a protective conductor circuit."

543-03-05 is concerned with earth monitoring systems with pilot wires
(not usually relevant to TN systems or house wiring).

543-03-06 requires joints in metal conduit to be screwed or to use
"substantial mechanical clamps" and forbids the use of "plain slip or
pin-grip sockets."

--
Andy