Work on TN installations come "the 18th"

[JohnW2]

One opton would be a ground rod ( at ground level ) and a substantial conductorm a raising earth, ran up to the top of the building. Each flat then connects it's MET to the rising earth.
Provided the rising earth does not penetrate the equipotential zone of a flat then that is OK. If however the rising earth does penetrate the equipotential zone of a flat then is has to be considered as an extraneous conductor and would therefore need to be bonded to the MET.

What difference do you perceive between "connecting" each flat's MET to the 'rising earth' (which would obviously be required) and "bonding" the 'rising earth' to each flat's MET (which you seem to be implying is something different)?

Kind Regards, John

 

[bernardgreen]

What difference do you perceive between "connecting" each flat's MET to the 'rising earth' (which would obviously be required) and "bonding" the 'rising earth' to each flat's MET (which you seem to be implying is something different)?

One is an "Earth" and the other is a "bond". As is so often stated bonding and earthing are not the same thing so therefore one cable cannot be both.

 

[ban-all-sheds]

If I had a buried pipe running near my house, and decided to connect another pipe to it and bring it into my house, would that be an extraneous-conductive-part?

 

[ericmark]

Sad to say I've seen that, someone altered their patio and built raised beds, then moved their shared service phone line earth into the said bed.

On a different phone line, customer was complaining their phone didn't work but the dog did knew when it was ringing. Their gas supply was replaced with a plastic pipe and the dog was chained to the internal steel pipe.

There is still a phone line earth at my late parents house, however it has not been connected to the phone for around 45 years, since the party line was replaced with a line just for that house, not seen a telephone with a party line button for at least 40 years it may be 50 years.

How old are you to remember them?

 

[SUNRAY]

There is still a phone line earth at my late parents house, however it has not been connected to the phone for around 45 years, since the party line was replaced with a line just for that house, not seen a telephone with a party line button for at least 40 years it may be 50 years.

How old are you to remember them?

I was with BT 1972 -1994.

I started seriously running jumpers 1975ish, when I finished my apprenticeship, and SS provision was still fairly common at that time. The incident with the dog happened in the heavy snow around 86/7 and I couldn't commute to work as the trains were completely covered over while parked in the station overnight, I had to work in/from the local exchange and was expected to do whatever work cropped up (like walking 1/2 mile up the road to stand on a ladder ).

SS lines were being seriously done away with mid 80's onwards, and certainly as system's X & Y exchanges were being installed as they do not have the facility. One of my duties in 1993 was surveying exchanges for changeover and checking on discrepancies between the various records. This included highlighting SS lines and arranging to get them eradicated as there were still some in existence.

So SS lines (or more correctly party lines) were still around as recently as 25 years ago.

 

[JohnW2]

One is an "Earth" and the other is a "bond". As is so often stated bonding and earthing are not the same thing so therefore one cable cannot be both.

Yes, but this is different (and, if I may say so, more than a little silly), since you are claiming that what is the (flat's) incoming earth is also an extraneous-c-p which needs to be bonded! One could just as well say the same of a TN-S earth - but we don't, because it would be a totally daft suggestion!

If you really want to regard an incoming earth connection as an extraneous-c-p, then this is an exception which proves the usual rule - since 'earthing' and 'bonding' would be the same - and would/should use the same cable (to run a G/Y bonding cable in parallel with the G/Y Earth cable really would be daft )

Kind Regards, John

 

[SUNRAY]

Yes, but this is different (and, if I may say so, more than a little silly), since you are claiming that what is the (flat's) incoming earth is also an extraneous-c-p which needs to be bonded! One could just as well say the same of a TN-S earth - but we don't, because it would be a totally daft suggestion!

If you really want to regard an incoming earth connection as an extraneous-c-p, then this is an exception which proves the usual rule - since 'earthing' and 'bonding' would be the same - and would/should use the same cable (to run a G/Y bonding cable in parallel with the G/Y Earth cable really would be daft )

Kind Regards, John

I recall some sort of problem bonding between lightening conductors and electrical earth where it would be done with flat bar and insulated G/Y to comply with 2 different regs.

 

[JohnW2]

I recall some sort of problem bonding between lightening conductors and electrical earth where it would be done with flat bar and insulated G/Y to comply with 2 different regs.

I suppose that the 'flat bar' in parallel might save it, but if weren't for that I don't think I would fancy the chances of "insulated G/Y" in the event of a lightning strike!

A good few years ago, lightning struck the TV aerial of a friend of mine. Forget about cables - the aluminium tube that was supporting it (a pretty long tube - he lived 'in the middle of nowhere' and struggled to get a decent signal) totally melted!

Kind Regards, John

 

[333rocky333]

Intrigued what happened round here last week, looking through the open door the staircase seems burnt away, it was lightning and my neighbours heard a large bang, its quite normal round here for the DB to be under the stairs, the Gas board were in attendance and dug the drive up and cut the gas off, whilst the fire brigade were still dousing the flames, only a month ago all the Gas pipes were cut off at the road and the meters and a yellow liner pulled through the remaining length.

https://www.time1075.net/dagenham-house-on-fire-after-being-struck-by-lightning/

https://www.london-fire.gov.uk/incidents/2018/may/house-fire-in-romford/

 

[bernardgreen]

since you are claiming that what is the (flat's) incoming earth is also an extraneous-c-p which needs to be bonded!

The flat's incoming "Earth" comes to the flat on the Neutral of the supply cable. That is not extraneous.

The "Earth" from the ground rod is an extraneous..... ? Yes exactly what is it classed as ?. It is the same as a metallic water supply pipe and as such has to be bonded to the "Earth" that comes to the flat on the Neutral

It seems to be that the connection to the ground rod is intended to act as an additional Earth to add to the Protective Multiple Earths of the PME distribution system ( which sometimes does not have "Multiple Earths" connected to it's Neutral )

 

[ban-all-sheds]

When people used water pipes for earthing did they also apply main equipotential bonding to them?

 

[EFLImpudence]

The flat's incoming "Earth" comes to the flat on the Neutral of the supply cable. That is not extraneous.

Only in that it is part of the electrical installation, thus removing it from the definition.

The "Earth" from the ground rod is an extraneous..... ?

Yes, until it becomes The Earth by loss of Neutral.
Until then, what current will it carry? 1/500th to 1/250th of the Neutral current?

Yes exactly what is it classed as ?.

Officially it is as you say below.

It is the same as a metallic water supply pipe and as such has to be bonded to the "Earth" that comes to the flat on the Neutral.

It could be removed until needed but as it is, yes, it will have to be bonded by what will be described as an Earthing Conductor.

It seems to be that the connection to the ground rod is intended to act as an additional Earth to add to the Protective Multiple Earths of the PME distribution system ( which sometimes does not have "Multiple Earths" connected to it's Neutral )

It is referred to as additional Earth but it is only just that.
Surely its real purpose is to provide THE Earth when the Neutral fails.

I fail to see how it can be PME if there are not Multiple Earths (albeit only two).

 

[EFLImpudence]

I must have saved the draft, but can't find it.

Does the Draft say this new requirement is for TN-C-S or just PME - and if it does, does anyone think that is what they mean?

That is if it says PME does it mean TN-C-S as well? If it says TN-C-S does it really mean that or just PME?

 

[ban-all-sheds]

The "Earth" from the ground rod is an extraneous..... ? Yes exactly what is it classed as ?. It is the same as a metallic water supply pipe and as such has to be bonded to the "Earth" that comes to the flat on the Neutral

So this is required?

It seems to be that the connection to the ground rod is intended to act as an additional Earth to add to the Protective Multiple Earths of the PME distribution system ( which sometimes does not have "Multiple Earths" connected to it's Neutral )

Common sense says that the ESQCR should be amended to require the earth rod to be connected to the supply neutral on the network side.

 

[ban-all-sheds]

it will have to be bonded by what will be described as an Earthing Conductor.

Bonding conductors, not earthing.