Understanding the electricity supply to my house (pole, underground cable, meter box, etc...)

[Max Rasa]

Partly cos I like to know everything... Partly because I'm a geek... And partly because we're going to have some electrical work done on the house which has made me curious.... I'd like to know more about the feed to my house...

The power lines come to us through the garden and reach a pole with transformer. From there the supply comes to us underground. Because the ground is lower at the back of the house, you can see the main cable going into the wall of the house. I'm guessing it then travels under the house to the meter box which is on the front of the house. The meter box has two fuses. The house has three consumer units. As we're having the consumer units changed and a partial rewire amongst other things, I'm not too worried about comments on the photos of the consumer boxes (but feel free to make them if you wish)...

... What I am more eager to know is anything you can tell me about the pole, transformer, underground line and meter box. Some of the things of particular interest...:

1. Earth/ground. How can I tell what the set up is for that? A sparkly told me there was a supplied earth, but there's only two overhead cables. But there are three cables running down the side of the pole and going into the ground.

2. Earth/ground - is there any way to test it? (I'll be running a music studio in the house which I've been told needs a low impedance path to ground)

3. I'd love to know what's what on the pole and how it works, so any explanations or links would be fantastic.

4. The diagonal "cable" with the yellow cover coming from the pole. Is that purely just a support or does it have something to do with the earth/ground?

5. Why two fuses in the meter box?

6. Can anyone tell me roughly how old those two fuses are?

7. How often are the power companies maps wrong? I was in touch with them today and they sent me a map which shows the cable running underground from the pole to the front of the house. But I can see a power line going into the back of the house (see photos). Odd...

8. Anything what you want to enlighten me with!

I've got no broadband at home and so it takes an age to upload anything. I'll therefore link to a folder on Google drive that has all the photos. Let me know if that's a problem and I'll upload the photos to the site when next at the library.

Sorry for such a long thread. Any thoughts most welcome. Cheers

MYB - Electrics - Google Drive - https://drive.google.com/folderview?id=1-5SRqpupjqCplW9hDkE06pA9UjCL1hU9

 

[Cid]

You have a TNCS earthing arrangement. The 'earth' comes from the neutral conductor. Use Google to find out how the earthing system works.

 

[mhar]

It appears tncs. There doesn't appear to be a pme plate on the pole. The yellow covering is for a stay, sometimes these are in hedges etc and not seen by the operators of the flailing hedge cutting machines and were often accidentally cut. The yellow covering is for increased visibility. The two switch fuses appear to be on your side of the installation, your electrician will tell you what they are supplying. Most dnos do not allow customers equipment in the meter box. Their maps are sometimes wrong, the cable at the rear may not be a dno cable

 

[Jim_e_Jib]

Your earthing looks to be TNC-S. John Ward gives a good explanation:

TNCS supply - https://www.flameport.com/electric/supply_types/TNCS_supply.cs4

Your electrician will be able to test the the earth path by doing a Ze test.

With the fuses in picture 6 - the black one bottom left is the fuse for the incoming DNO supply and is their property. The other two are switch fuses and belong to you. They will likely feed your other consumer units, or other equipment - it's not quite clear from the photo how they are connected as it looks as if the top one feeds the bottom one.

 

[Midwest]

Why have two threads running on a similar vein? Could get awfully confusing down the line or supply cable

 

[telectrix]

simpless. the electrickery comes on wires. these enable them pesky electrons to shuffle about. sadly, if laid on the ground, these electrons will escape into the mass of earth, that is why we have poles to keep them away from mother earth. these poles do have a drawback though. there's more of them over here than in Poland. (SWD, eat my shorts. .).

 

[Midwest]

there's more of them over here than in Poland. (SWD, eat my shorts. .).

@SWD 's not a real a Pole, just a wanabe. Do like his new avatar though.

 

[Squid]

simpless. the electrickery comes on wires. these enable them pesky electrons to shuffle about. sadly, if laid on the ground, these electrons will escape into the mass of earth, that is why we have poles to keep them away from mother earth. these poles do have a drawback though. there's more of them over here than in Poland.

(It it contains copper or lead I'll steal it. .).

 

[Squid]

Most of the questions that you asked are really easy to answer, I now challenge you to go on to Mumsnet and ask the question "how do womens minds/logic work"

;o))))

 

[Midwest]

A very unhelpful remark for the OP.

 

[Baddegg]

Most of the questions that you asked are really easy to answer, I now challenge you to go on to Mumsnet and ask the question "how do womens minds/logic work"

;o))))

They don’t work is the answer there...

 

[Midwest]

You should ask Amber Rudd. She made a very unfortunate remark today on Radio 2. It was a gift to another MP who can't count. Such is life.

Edit: We digress. Back on topic

 

[Max Rasa]

Huge thanks for all the helpful - and not so helpful - comments. Sorry it's taken me a while to return. I had to travel back home due to family illness and so have been away for a week.

I'll doubtless have other questions but while I get my head around all of that info I just wanted to say a big thank you.

Oh, and I thought that the other thread was sufficiently different enough to warrant it's own thread, and that adding the questions from that thread into this one would have been complete question overload. Hope that was ok.

Speak soon

Cheers

 

[Max Rasa]

I'm back! First I just want to say thanks again for those replies . They were really helpful. Cheers

Ok, so I do have a few more questions and help with any of them would be most appreciated.

A) There's some debate over the black cable going into the back of the house and whether that's the mains supply from the transformer. I think it is but others think not. What do you guys think (see pics labelled 04 and 05; link in first post)? The diameter of the swa is around 18mm. The black sheath says 600 - 1000V. It seems to be exactly the same as what comes into the meter box cutout (bottom left). There's no sign of the cable inside the property. In fact, where it enters the wall is roughly 30cm below the current floor level.

B) In the meter box, someone commented that the cutout ground connection block is corroded and I should maybe speak to the DNO about replacing it. What do you guys think?

C) Should I look to have the two switchfuses replaced for something with trip protection, so that the cables from the meter box to c/units are safe?

D) The two switchfuses in the meter cupboard... The white one controls the c/unit in the lobby. The black one controls the other two c/units, IE the understairs and cow shed mezzanine ones. The consumer units do work independently though. If you turn one off the others still work in all configurations.

E) Looking at the wooden pole in the garden again there is one wire coming down on one side and two on the other side, and all of them go down and into the ground. Why three??? I've taken some photos and put them in the same google drive folder. Link above but here it is again to save scrolling:

MYB - Electrics - Google Drive - https://drive.google.com/folderview?id=1-5SRqpupjqCplW9hDkE06pA9UjCL1hU9

The additional photos are labelled 3h, 3i, 3j and 3k.

Thanks a million for all the help.

 

[R-fur]

The three wires going into the ground will be
1 The concentric cable with Live and neutral inside
2 The LV earth to an earth rod about 8 meters away
3 The HV earth to an earth rod close to the base of the pole