I need to run a 10mm earth bonding cable right through the house to connect the incoming rising main (by the back door) to the main earthing point next to the CU (by the front door - great!).
Do I need to do this using one unbroken length of cable, or am I allowed to make a crimped joint to connect two shorter lengths? Reason is that of course I have a long piece on my reel, but it's just too short to reach right through the house and I'd rather use it unless the regs say I can't.
Thanks David
On Mon, 27 Jun 2005 19:59:42 GMT,it is alleged that Lobster spake thusly in uk.d-i-y:
I have no clue whether the regs permit this or not. I would however not suggest crimps in this case, personal preference would be a proper earth block at some accessible and not damp location, such as a cupboard, in a box with a blank plate on the front, labelled with the 'safety electrical connection - do not remove' sign.
As these earth blocks are often designed for 4-8 conductors, I would run the earth wire through, double it back and run it into the next connector, kind of forming two upside down U shapes, such that each part is clamped by 4 screws. Probably overkill, but the blocks are cheaper than a huge length of 10mm :-)
However, I would seriously advise waiting for other responses from this group as many are knowledgable about the regulations in detail and may know if this is forbidden.
HTH
As in all bonding practices, this one must be done un-broken. Joints only create resistive points along the conductor, so are not a good idea in safety bonding.
A joint is allowed. Joints in protective conductors like this are subject to the same rules as any other joints - i.e. they must be sound and protected from corrosion, etc. and must be accessible if not crimped, welded, brazed, soldered or resin potted.
An in-line crimped joint will be fine in a reasonably dry location. I'd protect it with overall heatshrink sleeving, although that's not actually required for sizes of 10mm^2 and over. Bear in mind that
10mm^2 is beyond the range of the usual insulated crimps so you'll need to beg, borrow or hire the appropriate heavier duty crimp tool and the correct crimp 'lug'.
Ah, the joys of uk.d-i-y! Thanks for the replies - but so far I have one "don't know", one "no" and one "yes"! I'll wait and hope that a consensus is reached... or can anyone give me a definitive source with the ccorrect answer?
If it's allowed, then I must admit I'd overlooked Andy's point that my crimping tool will be too small; so I'd probably end up usig Chip's solution with an earth block instead.
Years ago the approved way of jointing two thick wires was to hold them parallel and tightly wind onto them a 'spring' of about 26swg tinned copper wire. Then solder together. The spring provided the mechanical strength, and avoided the need to twist (and possibly weaken) the thick wires. Tidier for sleeving as well.
Would you not be allowed to make a second Earthing Plate near to your rising water main. In a 1935 Household book it told you how to dig an Earth Pit. A Zinc plate, household soot, sand and earth. All this about one foot down. I believe these days you can just whack a Copper spike in and connect to it.
x-- 100 Proof News -
So explain why it is allowed to bond one water pipe to another where you have a screwed clamp at each end of the wire plus the "joints" of the things that clamp around each pipe.
You're saying every piece of pipe must be bonded individually to the main earth by a single unbroken length of wire.
MBQ
The requirement is that 'main bonding' to the incoming water (and gas if you have it) pipes is done with a continuous unbroken length of wire from the main bonding connecting block adjacent to (or maybe in) your consumer unit. Supplementary bonding (as is required in bathrooms and similar places) doesn't have to be done with a single piece of wire.
This isn't true. If you believe it to be so, please cite the regulation number.
I now make the score three-two in favour of the 'Yes' camp... Where do I go for a definitive answer? My newly-expert BCO? ;-)
These days the bonding of water pipes is only to prevent the build up of static electricity as you can have plastic, non conducting, fittings in between pipes. The Earthing is not actually used as a Safety Earth in this case.
x-- 100 Proof News -
The "(as shown)" refers to seperate conductors from the main earth terminal to metal services pipes. The "looped with unbroken conductors" implies that broken conductors between the main earth terminal and the metal service pipe is not allowed. Therefore it ought to be a single length of cable.
So protection against indirect contact isn't the reason anymore then?
S'funny I always thought the idea was to provide a low resistance path for current to flow resulting in the fuse or circuit breaker operating and disconnecting fault from the supply especially in cases where the house pipework is copper and the underground supply is in non conductive plastic. Perhaps you know differently?
"Ask not your question upon the Usenet, for answers there will come three: 'Yea', and 'Nay', and 'Try a different newsgroup'."
;-)
Where on earth did you read that?
The problem is that neither BS7671 nor the OSG is specific on this matter. There is no paragraph in either (AFAICS) which categorically states "main EP bonding conductors must be unbroken between the main earthing terminal and the connection point to the service pipe". The phrase quoted is the closest you get to that, and IMO specifically refers to the situation where there is one wire which runs from the main earthing terminal first to one service and then to another. It is an annotation to an example diagram and isn't referred to in the text of the OSG, and doesn't refer to a paragraph number in BS7671.
It is *probably* meant to guard against the situation where the connection to the first service becomes loose. Where two wires are run, the second service will still be connected and since the services (e.g. gas & water) are usually connected metalically somewhere, a measure of bonding still applies. If there is just one cable, and it is broken (i.e. two lengths were used) at the first service, the connection to the second may also be lost. A single length of cable will not suffer here.
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".
Hwyl!
M.
Things have moved on a long way since 1935. In particular you can't "just whack a Copper spike in" because a wire isn't long enough. The idea is to bond metallic services so that they are all at substantially the same potential, and therefore they really need to be physically connected to the same earthing point. There are situations where two or more separate earthing systems are permitted, but I really don't see how they could apply in a domestic situation... erm... you *are* aware that this is *uk*.d-i-y?
Might I respectfully suggest, in the light of Part P, and particularly regarding your "static" answer elsewhere in the thread that you refrain from answering questions unless you have evidence (e.g. reference to BS7671) to back up your assertion?
Hwyl!
M.
Absolutely. I've never jointed cable to get the last bit on the drum used up - since that suggests you'll never need any more ever.
It's not exactly expensive after all.
The OSG says "Main equipotential bonding conductors maybe seperate (as shown) or looped with unbroken conductors", this is discussed to death further down the thread so I won't say anything further here. :-)
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