Water supply to garage

[anglia]

Hello, I just wondered if somebody could help me with a question I have please ?

My garage is powered by 15M of 3-core swa cable of 10mm csa via a metal box where the cable changes to 10mm t+e to enter the house cu and terminates onto a 32A mcb.

The cu in the garage is a metal unit and the swa goes staight into that.

The sockets are fed by a 16A mcb and the lights by a 6A mcb. There is a 63A rcd in the garage cu.

The main house feed is tn-s from an aged lead cable.

All this info is on a sheet of paper nicely included in the house cu - very thoughtful I guess !

Anyway, I want to add a water supply to the garage (just a cold supply) from the house and seeing as I have loads of 22mm copper pipe laying around, I was going to use that, buried deeply in my garden to protect from frost.

Simple so I thought until a friend of mine who is training to be an electrician said that I will have to get an electrician in to earth the pipework and put a spike into the ground near the garage for this earth.

Wouldn't the pipework already be earthed, seeing as it is soldered into the house pipework ?

Is this something an electrician definitely has to do or is it something a diy junkie like myself can do ?

Can anybody guess at a reasonable cost for this ?

I forgot to add that the house is about 65 years old if that makes any difference.

Thankyou.

 

[PrenticeBoyofDerry]

Is the armoured sheath of the SWA, connected to earth within the house, it maybe that you only need to bond the pipe within the garage back to the garage CU, or alternatively run plastic pipework.
Do you have the Ze readings of the garage CU?

 

[anglia]

Wow ! Thanks for the fast reply.

Sorry, no more information is written down anywhere that I can see but I can tell you that in the metal box adjacent to the house CU, the red core of the swa is connected to the red core of the t+e, the yellow core of the swa has green/yellow tape on it and is connected to both the green/yellow of the t+e and the little nut that holds the cable onto the metal box and the blue core of the swa has black tape on it and is connected to the black core of the t+e.

I don't really want to open the CU boxes themselves if I can help it as I don't fancy having loads of wires exposed. I can do it if it really needs to be done as I can completely turn off the house electrics from a separate switch that is in between the main cable and the house CU if it would help ?

As to your question about ze, I'm sorry but I can't answer that as to be honest I don't know what you're asking - sorry.

Thanks again for trying to help out though, it's much appreciated.

 

[PrenticeBoyofDerry]

The Ze reading could be with the document left for the electric or there could be another chart with garage CU.
But if in doubt the option of plastic pipework entering the garage, would exclude any additional bonding or a spike.

 

[anglia]

I'll have a look through all the paperwork that I got with the house to see if I can find anything. I'm guessing that this will be an official-looking printed document ?

The one with all the info on near the house CU was just an A4 sheet of paper hand-written. Looked like a bit of an afterthought ?

If I manage to find the electrics document, what will I be wanting to look for to be able to use my copper pipe ? Is there a magic figure in volts or something ? I know you mention using plastic but it's just that I've got all this pipe laying around and rather than spend any more money on new plastic stuff, I'd like to be able to use that.

Thanks again and sorry for all the questions.

 

[JohnW2]

I know you mention using plastic but it's just that I've got all this pipe laying around and rather than spend any more money on new plastic stuff, I'd like to be able to use that.

You'd only have to change to plastic for the last couple of feet, where it entered the garage, and could even change back to copper within the garage if you wanted.

Mind you, with the present price of copper, it could well be in your financial interest to sell all this pipe you have lying around and buy some plastic instead

Kind Regards, John

 

[PrenticeBoyofDerry]

The figure would be in Ω (ohms) not voltage.
I will try upload or link you to an EIC or schedule of tests where the figure would be expected to be found. I would hazard a guess though that bonding the metallic pipe back to the MET of the Garage CU, would acceptable.
If you look at the link below, on sheet one under supply characterists and earthing arrangements a figure for the Ze can be found here (External Loop Impedance) also on sheet three/schedule of tests the same figure should be found in the section in top left under Zs at DB (&#937.
http://www.wmjoiner.co.uk/Download/5 - Electrical Installation Certificate 17th Edition BS7671.pdf

Not all EICs are the same but they should have these results in-putted on them.

 

[mfarrow]

Don't bother with the copper. Solder joints will crack and leak if not done properly and DZR compression, which you should use instead of standard brass, will be more expensive.

MDPE on the other hand is cheap, flexible, and avoids the electrical problems as it's not extraneous.

 

[anglia]

You'd only have to change to plastic for the last couple of feet, where it entered the garage, and could even change back to copper within the garage if you wanted.

That sounds OK, I'll have to consider that. Thanks also to prenticeboyofderry for the forms to look for. I've got that much paperwork kicking about here, it'll be nice to know what I'm supposed to be looking for.

"mfarrow" thanks for the suggestion but I have no problems whatsoever soldering joints and I work in groundworks for a living so the correct trenching and back filling won't be an issue.

Thanks again people, I'll report back as soon as (or if !) I find the forms.

 

[JohnW2]

You'd only have to change to plastic for the last couple of feet, where it entered the garage, and could even change back to copper within the garage if you wanted.

That sounds OK, I'll have to consider that. ... "mfarrow" thanks for the suggestion but I have no problems whatsoever soldering joints ...

I'm not sure that it's necessarily your soldering skills that were being questioned but, rather the potential issues associated with buried soldered joints.

Kind Regards, John

 

[PrenticeBoyofDerry]

If the tube is half hard (table Y) laid between 750mm-1350mm underground, it can be jointed either by capillary or using type B manipulated joints.

 

[JohnW2]

If the tube is half hard (table Y) laid between 750mm-1350mm underground, it can be jointed either by capillary or using type B manipulated joints.

Is the long-term fate of a capillary (soldered) joint not dependent upon the composition of what it is buried in? The subsoil around my neck of the woods seems to be a cousin of battery acid

Kind Regards, John

 

[PrenticeBoyofDerry]

It would be worth consider testing to see if the soil is aggressive using indicator paper, pipes can be coated but also plastic piping can be effected by underground chemicals/gases.
I personally would use copper over the plastic alternative.

 

[john4703]

My reply may be a little off topic but copper pipe used underground is a soft copper and comes in long coils. It is different to the rigid pipes used inside a house. I'd suggest checking that the pipe you have is suitable for use underground and if not it may be better to sell the copper and buy blue MDPE pipe, it will cost about £25 for a 50 meter length

 

[PrenticeBoyofDerry]

Like I said Table Y.
And no need to apologise, as it is part of this topic.