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JamesF

JamesF's observatory build

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7 hours ago, DaveL59 said:

An earth spike (4ft) is relatively easy to do so long as the ground isn't littered with rocks under the surface. A 4lb hammer should drive it in ok, maybe easier if the ground is wet. Then fit the clamp on the end and 10mm earth wire back to the consumer unit to bond that to earth and the obsy should be fine.

Around here earth spikes are minimum of 2m or 2.2m long. Galvanized or copper coated.

There are several ways of getting them down into the ground:
Manual hammering.  Needs a stepladder and a helper to hold the spike straight.
Hammering with a contractors large hammer drill and hollow driver socket.
Keep adding water around the spike as you bang it in. It is supposed to run down around the spike.
Using water pressure from a hose to a long pipe to make the hole and replace the pipe with the spike.

I used two lump hammers followed by a sledge hammer as the resistance increased.
Clay soil and no rocks until nearly full depth @ 2.2m.
I was lucky and only hit a rock at full depth.

You couldn't get a 6" nail in where I once lived in Wales on an ice age moraine.
The local board replaced an old and wimpy pole transformer for us while we were there.
The earths for that were several, absolutely massive, stranded cables spread out on the field and buried for probably 50 yards each.

A serious cable clamp on top of a domestic earth spike, under a protective cap, ensures a long life connection.
The job is strictly for an authorized electrician over here. As is all outside electrical work and most inside.
I did the job while they were here, fitting new sockets indoors.
The sparks watched happily as I hammered the spike in for over half an hour.
Then nodded through my 2.5mmm earth cable connection to a single row of 3-Pin sockets indoors for my UK Hifi. Hum gone!

 

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hehe yeah has gone that way here for the most part where apart from "repairs" you're supposed to get someone who is part-P certified to do the work or have them check and certify your work afterwards. Back way back when, I've rewired houses from the meter, laying in new rings and main RCD/MCB distribution board etc. Ran the earthing down into the basement where I installed said spike as it was just a few turns of bare wire around a metal supply pipe (water or gas) in the old setup. Even installed galv trunking to protect the cabling that ran from the distribution board in the garage that was all earth bonded between sections etc. So a couple years after I left the ex had builders in doing other works and to see how they left it all was shocking, just trailed wires around, opened the trunking and didn't bother to re-cap it etc., what a mess. No wonder I'm usually reluctant to get a "professional" in to do works where I know I can do it at least as well myself 😉

 

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At the risk of starting an endless argument:

Modern piping is often plastic. Rural homes are almost certainly fed by miles of plastic hose.
Connecting the indoor metal pipes, if any, as an earth, will be lethal and based on a lack of basic electrical knowledge.

Discussions on forums, which have US members, suggests that the rules for earthing are as varied as the soils on which the building stands.
I claim absolutely zero knowledge and nobody should ever follow anything suggested on a forum.
Your "expert" advisor might be a trolling, psychopathic, serial killer!

ALWAYS seek EXPERT advice from a local, fully qualified electrician with experience of your local conditions.

Your having moved on from your own installation leaves those who follow on in a very precarious position.
Which through their own ignorance, of what they only think they should trust, might easily kill them.
This doesn't even begin to deal with the matter of lightning and adding extra earthing rods to an existing electrical system.

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8 hours ago, JamesF said:

I'm sure it won't do the job either.  Makes me quite uncomfortable.  That's what was there when we moved in though, and I've been wanting to replace it for years.  I think it's off an MCB on the main distribution board, though I have to admit that since we had everything reorganised last year I've lost track a bit (we had a modern board put in last year when we had the cellar made usable, to replace the old one that used cartridge fuses).  We should have Western Power in very soon to deliver a second phase to provide power for the barn conversion, so I'll get everything sorted then.

I'm reasonably convinced that a local earth spike should do the job ok.  The ground around that area tends to be quite damp.  That's one for the electrician when he visits.

James

If there are no extraneous metal parts in the out building 2.5 is ok, depending on load and distance.
If there are extraneous parts then 6 or 10mm will be needed for bonding depending on you supply type.

What is your supply type btw?

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49 minutes ago, Rusted said:

At the risk of starting an endless argument:

Modern piping is often plastic. Rural homes are almost certainly fed by miles of plastic hose.
Connecting the indoor metal pipes, if any, as an earth, will be lethal and based on a lack of basic electrical knowledge.

Discussions on forums, which have US members, suggests that the rules for earthing are as varied as the soils on which the building stands.
I claim absolutely zero knowledge and nobody should ever follow anything suggested on a forum.
Your "expert" advisor might be a trolling, psychopathic, serial killer!

ALWAYS seek EXPERT advice from a local, fully qualified electrician with experience of your local conditions.

Your having moved on from your own installation leaves those who follow on in a very precarious position.
Which through their own ignorance, of what they only think they should trust, might easily kill them.
This doesn't even begin to deal with the matter of lightning and adding extra earthing rods to an existing electrical system.

I don't disagree re getting expert advice, that's generally a good way to go if planning some new works and esp so if you've no relevant expertise yourself.

In terms of my past installations, they were all done to building code at that time and in some aspects to industrial above domestic at that, so I've no worries on that front. They all passed inspection by the relevant authority on hand-off or you wouldn't be able to connect to the main supply into the building 🙂 I have however seen several dodgy installs that have been inherited when buying another property too, like main power and lighting cross-connected, regular ring wiring run to outbuildings in garden hose just inches under the edge of flower beds etc, scary the way some have done installs and a new unsuspecting owner is put at risk...

 

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50 minutes ago, wxsatuser said:

If there are no extraneous metal parts in the out building 2.5 is ok, depending on load and distance.
If there are extraneous parts then 6 or 10mm will be needed for bonding depending on you supply type.

What is your supply type btw?

I'm very sure there will be loads that exceed the maximum capacity of a single run 2.5mm T&E.

The supply type is an interesting question.  It definitely used to be TT, and there's an earth rod next to the house wall where the supply comes in.  At some point it was changed to TN-C-S (I think), the earth being provided by conductors buried in the field above our house (which is also where the transformer is).  However, the earth rod may still be connected.  The cabling is a bit obscured and I can't see exactly where it goes.  When they eventually turn up to provide the additional phase I'll make sure it's properly documented and if the earth rod isn't being used I'll probably remove it so there will be no confusion in the future.

James

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2 hours ago, Rusted said:

At the risk of starting an endless argument:

Modern piping is often plastic. Rural homes are almost certainly fed by miles of plastic hose.
Connecting the indoor metal pipes, if any, as an earth, will be lethal and based on a lack of basic electrical knowledge.

Discussions on forums, which have US members, suggests that the rules for earthing are as varied as the soils on which the building stands.
I claim absolutely zero knowledge and nobody should ever follow anything suggested on a forum.
Your "expert" advisor might be a trolling, psychopathic, serial killer!

ALWAYS seek EXPERT advice from a local, fully qualified electrician with experience of your local conditions.

Your having moved on from your own installation leaves those who follow on in a very precarious position.
Which through their own ignorance, of what they only think they should trust, might easily kill them.
This doesn't even begin to deal with the matter of lightning and adding extra earthing rods to an existing electrical system.

We had a professional survey done of our electrics.

He said the best bit was my workshop, which I wired up myself - ring main, spur lighting + spur for the heater, all off a dedicated distribution box with RCB.

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3 hours ago, JamesF said:

I'm very sure there will be loads that exceed the maximum capacity of a single run 2.5mm T&E.

The supply type is an interesting question.  It definitely used to be TT, and there's an earth rod next to the house wall where the supply comes in.  At some point it was changed to TN-C-S (I think), the earth being provided by conductors buried in the field above our house (which is also where the transformer is).  However, the earth rod may still be connected.  The cabling is a bit obscured and I can't see exactly where it goes.  When they eventually turn up to provide the additional phase I'll make sure it's properly documented and if the earth rod isn't being used I'll probably remove it so there will be no confusion in the future.

James

You should be able to tell if its TN-C-S as the main coming in should be two wires and an earth wire should come out of the neutral in the cutout.
The TN-C-S cutout may have a sticker on it that points out it's a PME system, the company neutral is earth staked multiple times in it's run to the consumer.

If the main is /was TT then out buildings would need earth rods and RCDs as fault current might not be large enough to blow fuses.

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1 hour ago, wxsatuser said:

You should be able to tell if its TN-C-S as the main coming in should be two wires and an earth wire should come out of the neutral in the cutout.
The TN-C-S cutout may have a sticker on it that points out it's a PME system, the company neutral is earth staked multiple times in it's run to the consumer.

If the main is /was TT then out buildings would need earth rods and RCDs as fault current might not be large enough to blow fuses.

I'm not 100% sure what's coming in because the positioning of all the components means it's not absolutely clear what wiring actually enters the cut-out.  I know there's at least one four-core cable that they don't need to replace to provide us with a second phase from the transformer and it presumably already carries live, neutral and earth.  That earth may also be connected to the earth spike, but I just can't tell.  There's no earth on the distributor's side of the transformer at the end of our field however; that's all hooked up from multiple earth stays under our field.

James

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When we came to France house-hunting, I quickly started to focus on the power distribution - whatever anyone thinks as a poor installation is nothing comapred to what we have seen here...

James, if you are having a second phase commissioned, please be aware across the phases will be over 400 volts.

From memory of my higher education, where I did a years' module on three-phase power transmission, the supply is distributed on three wires, one per phase. At the step-down transformer, the three phase windings change configuraiton to make a 4-wire system. Three for the phases, the fourth a Neutral. Think about the shape of a Y with the centre being the neutral. This is then grounded at the transformer and this is the ground reference.

Ideally, the current in each phase is the same and if so, then no current would pass down the neutral wire (Kirchoff's law) Any difference in current will lead to current flow through the neutral and some offset in Neutral voltage to earth.

I would guess the four core cable you have would be the three phase supply and two of them have been isolated at some day.

Please make sure your electrician explains what you end up with before they leave.

My house has a three phase supply with it distributed around the house with at least 30mcb's as France does not do ring mains.

Take care.

Gordon.

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Took a detour via Screwfix after swimming today to collect about 20m of trunking for the internal cabling and got on with installing some of it this evening.  I didn't get as far as I wanted, but I do at least have a plan of where all the sockets etc. will go now, and how I'm going to connect up the 12V supplies to the piers.

James

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19 hours ago, JamesF said:

Took a detour via Screwfix after swimming today to collect about 20m of trunking

It's definitely cheating when your trunks stretch the whole length of the pool.

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2 minutes ago, Stub Mandrel said:

It's definitely cheating when your trunks stretch the whole length of the pool.

I shan't be wearing those knitted woolly ones again.

James

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4 hours ago, Stub Mandrel said:

It's definitely cheating when your trunks stretch the whole length of the pool.

Brilliant!!  Laughed so much it brought tears to my eyes!

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