I will need to earth our gas and water supplies - at present there is just the one elderly dog eared 6mm earth lead from the Board terminal to the consumer unit.

Gas is no problem.  The water stop tap is at the rear of the building and due to concrete floors the easiest route means leading a cable up into the bathroom and down again.  

Is it o.k. to have a run of about 20 - 25 feet in 10mm?

Is it o.k to earth to the earthing bar in the consumer unit or do I need a separate earthing terminal in line with the main one? .

P.S. Before anyone says anything, this is all part of a job commenced before Jan 1st.........



Thanks

John Davies

No restricition on bonding conductor length.

Ensure you bond within 600mm of the stop tap/gas meter, and before any tee's.

Use 'Blue' clamps if in a damp environment, or ('green' if corrosive )

Upgrade your main earth to 16mm, and your mains tails to 25mm a tthe same time.

Yes you can use the earth bar in the CU for the bonding.  Many modern units have a few terminals labelled 'B'.

What type of CU do you have at the moment??

Thanks for this.

C.U. is a Crabtree starbreaker.

John

Re. my rewire.

Yes, it has a RCD.

As to Part P, as I said originally, the work was started before 1st. January, so I thought it came under the period of grace mentioned elsewhere on this forum - 30th. March, isn't it?

It will in any case have to be checked in due course as

(a) there will be a kitchen going up and as it wasn't started before 1st. Jan all the wiring for that will come under building control which as far as I can see will also mean having to test the exisiting installation (i.e. my rewire) for compliance with Building Standards.  

and

(b) I will need it checked out anyway in due course as otherwise I could invalidate my house insurance if anything was wrong - or could be said to be wrong, for that matter.

and

(c) anyone can make errors - even a talented amateur like me - and I'd rather get it checked out for piece of mind....it cannot be worse that the horrible and lethal job it replaced - some of which was still rubber!


Thanks,

John D

Lectrician

Don't forget the 'P' Word


Sorry Lec i meant PRACTICABLE lol

547-02-02
The main equipotential bonding connection to any gas, water or other service shall be made as near as
practicable to the point of entry of that service into the premises.
Where practicable the connection shall be made within 600 mm of the meter outlet union or at the
point of entry to the building if the meter is external.

LOL CPW.......

Sorry.....

Yup.  If your rising main is chased into the wall until beneith the floor, with just the arm of the stop cock emerging from the wall, then bond where PRACTICABLE

In the 60/70's it was not uncommon for the rising main to appear in the WC downstairs, and the pipework and stopcock to be burried in the wall.  I have bonded a few rising mains in the airing cupboard above the WC, or in the loft if it is a bungalow.

Cheers CPW......but of course, the DIY-er dreaded PART-P still plays a role

And gas.....well.......

If the meter is in a box outside, you can bond there, or at the point where it enters the building

I thought of something like this

main switch side
Cooker 40a
Central heating 16a
Ground floor lights 6 a
Kitchen and utility lights (possibly) 6 a
(or in with rest of ground floor - it's only a 3 bed house)
First floor lights 6 a

RCD side

Garage 32 a - taken by 6 mm flat  to separate wylex fusebox, with 16 a and 6 amp MCB for power and light respectively.  I may need a different, less sensitive (type d, is it?)  MCB at both ends to cope with my single phase welder.

Kitchen and Utility power 32a(posh name for a washing machine and tumble drier in a very small cubby hole!)
Ground floor power (dining room, hall, living room) 32 a
First floor power 32a
Loft 16a

What do you think?

Question - can the loft supply - a 16a radial - also supply a 1kw heater in bathroom and a 250w towel rail in the bathroom, or is this best included on the upstairs ring (which would make this a lot longer but still within limits).

Thanks

John

There is no actual maximum length for a main bonding conductor, but there is a maximum impedance of 0.05Ω between the extraneous conductive part (e.g. gas pipe) and the main earthing terminal. Assuming good contact at the BS951 clamp then this give a max length for 10mm² of 27m at 20°C.

(The same value applies to suppplementary bonding, which gives a max length for 4mm² of around 10m... for those of you with humungous bathrooms! )

Thanks.  Radiant is on its own pull switch - I thought a fused spur box coupled to the fire ( as at present) would be o.k.,  and a fused neon switch in the adjoining bedroom for the towel rail.  

John Davies