32amp Commando Socket Problem.

[GUMPY]

If my brain is still working It is no longer part of BS7671 to bond everything.

However copper gas main does need bonding!

[GUMPY]

12 minutes ago, Alan de Enfield said:

Interesting read - thank you.

 

Plastic supply pipe to the incoming stop-cock and then copper pipe in the building still requires bonding tho', but plastic pipe within the building does not.

Every day is a school-day.

a plastic water pipe entering the house and then being connected to a copper pipe is not an extraneous conductive part that requires main equipotential bonding to comply with BS7671

Its a complex subject as to what needs bonding, even qualified electricians don't agree

Edited December 30, 2018 by Loddon

[Alan de Enfield]

2 minutes ago, Loddon said:

a plastic water pipe entering the house and then being connected to a copper pipe is not an extraneous conductive part that requires main equipotential bonding to comply with BS7671

However if its copper entering the house then plastic then copper the copper needs bonding

Maybe I misunderstood Nick's link ?

 

If the incoming pipes are made of plastic, but the pipes within the electrical installation are made of metal, the main bonding must be carried out. The bonding being applied on the customer side of any meter, main stopcock or insulating insert and of course to the metal pipes of the installation.
 

[GUMPY]

8 minutes ago, Alan de Enfield said:

Maybe I misunderstood Nick's link ?

 

If the incoming pipes are made of plastic, but the pipes within the electrical installation are made of metal, the main bonding must be carried out. The bonding being applied on the customer side of any meter, main stopcock or insulating insert and of course to the metal pipes of the installation.
 

Only read second link! That was from an American site ,  The rules have changed in the last couple of years under earlier BS7671 you did have to bond everything under the latest versions you don't however if carrying out wiring in the UK it must comply with BS7671/2018.

Edited December 30, 2018 by Loddon
Cos I didn't read first link

[Alan de Enfield]

4 minutes ago, Loddon said:

That was from an American site

Are you sure ?

Published by Hepworth Plumbing (UK) and written by a member of the IEE 

[nicknorman]

15 minutes ago, Loddon said:

a plastic water pipe entering the house and then being connected to a copper pipe is not an extraneous conductive part that requires main equipotential bonding to comply with BS7671

Its a complex subject as to what needs bonding, even qualified electricians don't agree

If you are suggesting that a house full of copper piping doesn’t need the pipes to be Earth bonded just because the incoming water main is plastic, you are definitely wrong.

[Biggles]

1 hour ago, Biggles said:

On better understanding and looking again I am TNC-S. It's about 15 years old this lot. 

 

Should I still put in an earth spike and PME to the water main. I could easily do the gas main as well but I know its plastic from the road to the meter. 

I've done a bit more digging and now I'm not sure if it's TNC-S after all. There is no separation of the "neutral" from the "Earth". In the video there is a an outer layer of for the Earth. 

[GUMPY]

20 minutes ago, Alan de Enfield said:

Are you sure ?

Published by Hepworth Plumbing (UK) and written by a member of the IEE 

The second link he posted was american

[GUMPY]

21 minutes ago, nicknorman said:

If you are suggesting that a house full of copper piping doesn’t need the pipes to be Earth bonded just because the incoming water main is plastic, you are definitely wrong.

Not what I said.

There is not a requirement to bond  everything as it used to be.

Its complex and to be honest I am not qualified on BS7671/2018 as I've retired but do hold earlier qualifications and the rules on bonding have become much more relaxed than they were.

13 minutes ago, Biggles said:

I've done a bit more digging and now I'm not sure if it's TNC-S after all. There is no separation of the "neutral" from the "Earth". In the video there is a an outer layer of for the Earth. 

Presumably that green and yellow wire goes to the consumer unit to provide the earth there If it does that is TN-C-S.

 

Just a thought you haven't got the N and E wires crossed feeding the socket have you?

 

[Biggles]

8 minutes ago, Loddon said:

Not what I said.

There is not a requirement to bond  everything as it used to be.

Its complex and to be honest I am not qualified on BS7671/2018 as I've retired but do hold earlier qualifications and the rules on bonding have become much more relaxed than they were.

Presumably that green and yellow wire goes to the consumer unit to provide the earth there If it does that is TN-C-S.

 

Just a thought you haven't got the N and E wires crossed feeding the socket have you?

 

No all polls are correct. See the original pictures at the top of the post to confirm. 

I think I'm going add an earth rod. How long should it be ideally. They seem to come in 4' lengths 

[WotEver]

1 hour ago, nicknorman said:

Interesting link here whilst we are on the subject. It seems that a very high current (>200 mA) is less likely to cause fatality than current in the 100-200mA range. I didn’t know that.

 

https://www.asc.ohio-state.edu/physics/p616/safety/fatal_current.html

I didn’t know that either. I was wondering why that might be the case and then I read further to see the explanation which I found very interesting:

Quote

 

As the current approaches 100 milliamps, ventricular fibrillation of the heart occurs - an uncoordinated twitching of the walls of the heart's ventricles which results in death. 

Above 200 milliamps, the muscular contractions are so severe that the heart is forcibly clamped during the shock. This clamping protects the heart from going into ventricular fibrillation, and the victim's chances for survival are good.

 

 

Edited December 30, 2018 by WotEver
Removed duplication.

[GUMPY]

4 minutes ago, Biggles said:

No all polls are correct. See the original pictures at the top of the post to confirm. 

I think I'm going add an earth rod. How long should it be ideally. They seem to come in 4' lengths 

 

The pictures dont confirm that as that tester cannot check if N & E are swapped.

Have a physical look as that is the only 100% way to confirm it.

 

[Biggles]

10 minutes ago, Loddon said:

 

The pictures dont confirm that as that tester cannot check if N & E are swapped.

Have a physical look as that is the only 100% way to confirm it.

 

? I'll do that right now. 

What about earth rod length? 

[nicknorman]

38 minutes ago, Loddon said:

The second link he posted was american

yes but that was nothing to do with pipe bonding!

[WotEver]

1 minute ago, Biggles said:

What about earth rod length? 

My understanding is that it entirely depends on the resistivity of the soil. 1.5m seems to be the minimum but dependant on the soil they are sometimes best laid flat as opposed to hammered in vertically.

 

If the resistance between the earth connection and actual earth is below 40 ohms, measured with an insulation impedance tester (Megger), then there’s no point fitting one anyway. The neutral/PME leg is already earthed at multiple points between the supply and your property. It won’t do any harm to fit one, but I’m unsure if it would contravene current regs. 

[BEngo]

14 minutes ago, Biggles said:

I think I'm going add an earth rod. How long should it be ideally. They seem to come in 4' lengths

I cannot see that this will help with your original problem. The RCD checks that the live and neutral currents do not differ by more than 30 ma. It does not know or care why there is a difference or how the "missing" current is getting back to the transformer neutral. Adding an earth rod will not remove the existing current path by passing the RCD and causing it to trip.

 As gas as the installation earth is concerned start by having a good look at the local power poles. If there is a red label with the legend PME on some or all then you most likely have TNC-S  installation.  If you make the system TT earth with an earth spike the whole installation has to be protected by a single  30 mA RCD IIRC. That may have changed with the regs which come in to force tomorrow. My recommendation would be to get a qualified sparky to look at your present set up and confirm that you have a proper earth and what sort it is. There are testers for proving earths are good.

 

N

[GUMPY]

8 minutes ago, WotEver said:

My understanding is that it entirely depends on the resistivity of the soil. 1.5m seems to be the minimum but dependant on the soil they are sometimes best laid flat as opposed to hammered in vertically.

 

If the resistance between the earth connection and actual earth is below 40 ohms, measured with an insulation impedance tester (Megger), then there’s no point fitting one anyway. The neutral/PME leg is already earthed at multiple points between the supply and your property. It won’t do any harm to fit one, but I’m unsure if it would contravene current regs. 

If an earth spike is fitted and there is a neutral failure in the cable from the substation to your property then your property and any neighbours downstream of the break will be using the earth stake as a neutral. So IMO not a good idea to fit one.

I saw this happen where a truck broke the neutral in some overhead lines to a group of houses, no one noticed until the earth cable started smouldering.

Edited December 30, 2018 by Loddon

[Boater Sam]

Sorry I mentioned it now. I was only trying to help.

Bonding all metallic pipework to the supply earth block will do no harm.

I would seek professional advice before doing any alterations to the main earthing arrangement, its been years since I worked to regs so I shut up now.

[WotEver]

1 hour ago, Loddon said:

If an earth spike is fitted and there is a neutral failure in the cable from the substation to your property then your property and any neighbours downstream of the break will be using the earth stake as a neutral. So IMO not a good idea to fit one.

I saw this happen where a truck broke the neutral in some overhead lines to a group of houses, no one noticed until the earth cable started smouldering.

Yes, I seem to recall that the size of cable for a local earth spike has to be at least as big as the incoming L & N but I may be remembering it wrong and regardless, the regs change in a couple of days anyway. 

[Sea Dog]

2 hours ago, WotEver said:

I didn’t know that either. I was wondering why that might be the case and then I read further to see the explanation which I found very interesting:

 

New one on me too. When I served my time they used to say "Volts jolts; mills kills".  Seems they were probably even more right than they meant to be!

[Biggles]

3 hours ago, Biggles said:

? I'll do that right now. 

What about earth rod length? 

 

3 hours ago, Loddon said:

 

The pictures dont confirm that as that tester cannot check if N & E are swapped.

Have a physical look as that is the only 100% way to confirm it.

 

I've checked it and it is definitely connected each end Brown +ve to the MCB, Black to -ve and Grey to earth. Also checked the terminal marking on the back of the socket and that everything is going through the switch correctly. 

[Sea Dog]

6 minutes ago, Biggles said:

 

I've checked it and it is definitely connected each end Brown +ve to the MCB, Black to -ve and Grey to earth. Also checked the terminal marking on the back of the socket and that everything is going through the switch correctly. 

There's a knockout missing from the back of the box, effectively negating the cover seal. Are you sure your issue isn't damp related - it doesn't take much.

[nicknorman]

Are you sure that at the other end, grey is connected to earth and black to neutral? And that the central connection on the socket is for earth? I know you say it is, but the most likely scenario is an earth-neutral swap somewhere. Double check EXPECTING it to be wrong, not confirming that it’s right!

Edited December 30, 2018 by magpie patrick
Correct wiring swap

[Keith M]

A very odd colour code is being used for a single phase installation.

Both Black and Grey are live or line conductors in a three-phase installation 

The earth cable should be Green and Yellow.

Ferrules should be used on multi-strand cables.

[Biggles]

42 minutes ago, nicknorman said:

Are you sure that at the other end, grey is connected to earth and black to neutral? And that the central connection on the socket is for earth? I know you say it is, but the most likely scenario is a live neutral swap somewhere. Double check EXPECTING it to be wrong, not confirming that it’s right!

Yes absolutely sure. I can take a photo of the CU end later.