TT earth rod to shed or non connected garage..advice please

[dogwind]

Hi i have been trying to find in either the osg or regs book where it states that a shed or garage not connected to the house must use a TT earthing system instead of using the house PME, i have been told from a Niceic that it must be TT and also been told by elecsa that a PME is ok to use, so i would like to know for sure what it correct. Thank you

 

[davesparks]

You won't find any regulation stating that you either can or can't.

You need to assess the requirements for bonding and establish whether it is better to extend the equipotential zone or set up a seperate earthing system if it is required.

GN8 has all the info along with very good diagrams.

 

[telectrix]

as usual niceic have got their stupid head on. what a load of bollox. see above post.

 

[dogwind]

Thanks for your replies, its been driving me mad trying to find it written down anywhere, i also had a nic electrician telling me the other day he was told he had to do an earth bond to a lightning condutor on a house which i feel isnt right, if it did get struck by lightning then that could then travel through all the earthing into the house, and unless i am wrong i think a lightning conductor is sort of like a TT rod and you are told never to combine TNCS PME earthing to a TT system with a connecting earth!

 

[davesparks]

Where are you getting this nonsense from?

Lightning conductors are an ECP and should be connected to the MET by a main bond.

Adding earth rods with a good Ra to the origin of a PME installation is a very good idea.

 

[Silly Sausage]

Dog, I hope you're not an NICEIC member and paying them your hard earned for incorrect advice.

Yet another NICEIC ------- for the collection!!!

 

[dogwind]

Regarding the lightning conductors its not something i have ever done myself but was told that you must never connect a TNCS and an earth rod (TT) earth together because if a fault develops on the supply side into the building it can use your PME system down along the earth rod for its fault path.

 

[Octopus]

Oh dear......

 

[davesparks]

Regarding the lightning conductors its not something i have ever done myself but was told that you must never connect a TNCS and an earth rod (TT) earth together because if a fault develops on the supply side into the building it can use your PME system down along the earth rod for its fault path.

Told by who?

For a start an earth rod does not automatically mean a TT system, both TNCS and TNS distribution employ earth rods too!

Have you read the regulations with regards bonding? They specify lightning protection systems as one of the items which require bonding.

A metal water or gas pipe can also present as low a resistance to earth as any lightning protection system, do you not bond them either?

 

[dogwind]

Yes forget the lightning rod bit it was just another thing on my mind, and yes i do bond the gas and water, When i did my electrical training (quite a few years ago now) i can remember someone asking about caravan points have to have its own earth rod and i asked why it couldnt have both earthing systems and he said about a fault from the TNCS system has the potential to go through the caravan and into the earth rod. Myself i think the more means of earthing a system getting the resistance down as low as possible has got to be a good thing.
Also a electrician i do alot of work with has just done the car charging point course that was an NICEIC one and he had said that all buildings not connected to the main house has GOT to have an earth rod for its earthing and must not use the pme earth, when the tutor was questioned about it by sparks on the course he said it seems a thing where older electricians use a rod while the newer trained ones do it wrong and use the TNCS house earth. Also regarding the water bond i have had people tell me if the water is in plastic pipe then you need to cut some copper into it so you can bond it, but it states in the OSG that if its plastic pipe then it dosent require bonding.

 

[telectrix]

caravans and car chargers are a different kettle of smelly swimmers. with PME systems, the loss of the supply neutral could cause problems as a caravan has a metal skin. so TT is used . i imagine it's a similar scenario for the car charging points.

 

[dogwind]

caravans and car chargers are a different kettle of smelly swimmers. with PME systems, the loss of the supply neutral could cause problems as a caravan has a metal skin. so TT is used . i imagine it's a similar scenario for the car charging points.

It was the car charging points that has got me thinking about outbuildings must have a an earth rod because of what my mate who has been on the course said... going by the NIC insturctor both him and myself have been doing it wrong for years but ELECSA have told us we doing it right...god knows who is right.

 

[davesparks]

Forget what the NICEIC and ELECSA have to say and read the sodding regulations!

It is all explained clearly in guidance note 8, with nice clear pictures too!

 

[dogwind]

I will get it back out and have a read through it again, just makes you doubt yourself when so called experts are telling you different things all the time.

 

[trev]

The NIC are reknowned for making up their own regulations mate. None of them have any basis in fact.
An example is the nonsense they came out with a couple of weeks ago that anything which tests out at greater than 6.6 K ohms did not need to be bonded.

 

[Simonslimline]

Yes forget the lightning rod bit it was just another thing on my mind, and yes i do bond the gas and water, When i did my electrical training (quite a few years ago now) i can remember someone asking about caravan points have to have its own earth rod and i asked why it couldnt have both earthing systems and he said about a fault from the TNCS system has the potential to go through the caravan and into the earth rod. Myself i think the more means of earthing a system getting the resistance down as low as possible has got to be a good thing.
Also a electrician i do alot of work with has just done the car charging point course that was an NICEIC one and he had said that all buildings not connected to the main house has GOT to have an earth rod for its earthing and must not use the pme earth, when the tutor was questioned about it by sparks on the course he said it seems a thing where older electricians use a rod while the newer trained ones do it wrong and use the TNCS house earth. Also regarding the water bond i have had people tell me if the water is in plastic pipe then you need to cut some copper into it so you can bond it, but it states in the OSG that if its plastic pipe then it dosent require bonding.

A test to verify if it is extraneous or not should be carried out to confirm if bonding is or is not required. Again GN8 explains this.

 

[telectrix]

as above. if incoming water is plastic, then no bonding required. any metal pipes should be tested to see id they are extraneous or not. IR test from suspect pipe to MET. if reading is >22kΩ, then it's NOT extraneous, and does not require bonding. forget any niceic made up figures.

 

[dogwind]

The NIC are reknowned for making up their own regulations mate. None of them have any basis in fact.
An example is the nonsense they came out with a couple of weeks ago that anything which tests out at greater than 6.6 K ohms did not need to be bonded.

I have never registered myself with NIC but i used to work for a company that was and after i saw the work and stuff that was going on i decided i never would do.
A customer i work for had some electrical work done that was very bad and she contacted the council building control and was told by them they havent got time to follow it up, and would only come out if she had been hurt or maybe a fire. just shows the whole part P thing is a farce.

 

[Engineer54]

Hmmmm, now i wonder how the DNO's manage to provide all those Protective Multiple Earths in PME and even the TNC-S installations?? And NO, TNC-S isn't the same as PME!!

TT earth (rods mats, tapes etc) can be mixed with ANY of the TN earth systems, (TN-S, TNC-S, PME). It is not recommended that TN systems are mixed!!

Ignore anything a NICEIC spokesman states without confirmation from a known trusted source (that you'd be better off seeking in the first place anyway) .... Oh and it is now acceptable to use a domestic PME supply for car charging points!!

 

[Engineer54]

as above. if incoming water is plastic, then no bonding required. any metal pipes should be tested to see id they are extraneous or not. IR test from suspect pipe to MET. if reading is >22kΩ, then it's NOT extraneous, and does not require bonding. forget any niceic made up figures.

Just because a service water or gas pipe enters a building in plastic doesn't mean that the rest of the internal metal pipework will not be extraneous. Depending on the construction method of the building (especially concrete framed c/w concrete floors and ceilings) as well as the installation of the pipework, these metal pipes can very easily pick up extraneous potentials from the buildings fabric. That's why you should always test and not assume anything, even when the incoming supply pipes are in plastic....

 

[HandySparks]

Just because a service water or gas pipe enters a building in plastic doesn't mean that the rest of the internal metal pipework will not be extraneous. Depending on the construction method of the building (especially concrete framed c/w concrete floors and ceilings) as well as the installation of the pipework, these metal pipes can very easily pick up extraneous potentials from the buildings fabric. That's why you should always test and not assume anything, even when the incoming supply pipes are in plastic....

Indeed, a building's metal pipwork may be extraneous, even if supplied via a plastic incoming pipe. This raises the question, at what point should it be bonded? The requirement to bond close to the point at which the supply enters the building would appear to be irrelevant, as that's not the point at which the external potential is being introduced. In fact it may be impossible to determine why the pipework is extraneous without disconnecting sections for testing.

I recon this happens quite frequently with, say, a plastic water supply and metal gas supply pipe. The water pipes may test as extraneous, but only because they're connected to ground via the boiler and gas pipe. In which case, I would say that only one main bond is required, where the gas pipe enters.

 

[dogwind]

Hmmmm, now i wonder how the DNO's manage to provide all those Protective Multiple Earths in PME and even the TNC-S installations?? And NO, TNC-S isn't the same as PME!!

TT earth (rods mats, tapes etc) can be mixed with ANY of the TN earth systems, (TN-S, TNC-S, PME). It is not recommended that TN systems are mixed!!

Ignore anything a NICEIC spokesman states without confirmation from a known trusted source (that you'd be better off seeking in the first place anyway) .... Oh and it is now acceptable to use a domestic PME supply for car charging points!!

Thanks for your reply, he only did the charging point course last week and thats when he was told must use an earth rod and not the house earth. Was also told you must inform the DNO of every point you put in so they can keep a check on their loadings.

 

[Engineer54]

Thanks for your reply, he only did the charging point course last week and thats when he was told must use an earth rod and not the house earth. Was also told you must inform the DNO of every point you put in so they can keep a check on their loadings.

They originally came out with all the scaremongering about using PME supplies, but as far as i know have backed down and now allow PME supply sources to be utilised....

I don't understand why the DNO need to be informed about a car charging point being installed at a domestic residence on the basis of loadings?? Do you need to inform them if you install a storage heater, or two?? NOPE!!!

Are they going to refuse or deny the homeowner the right to charge a battery driven car from his household supply now?? lol!!

 

[dogwind]

They originally came out with all the scaremongering about using PME supplies, but as far as i know have backed down and now allow PME supply sources to be utilised....

I don't understand why the DNO need to be informed about a car charging point being installed at a domestic residence on the basis of loadings?? Do you need to inform them if you install a storage heater, or two?? NOPE!!!

Are they going to refuse or deny the homeowner the right to charge a battery driven car from his household supply now?? lol!!

Yes we both said that same sort of thing about telling the DNO, maybe they are worried about loadings with the government trying to push charging points but your main house supply will only allow a maximum load anyway so i cant see the point.

 

[davesparks]

It doesn't matter how many charging points there are installed, they aren't going to add any load until you plug a car in to it.
Now how many people have got a battery powered car to plug in to one of these things?

And why do they need a special socket to charge it from?

 

[Guest77]

Regarding the lightning conductors its not something i have ever done myself but was told that you must never connect a TNCS and an earth rod (TT) earth together because if a fault develops on the supply side into the building it can use your PME system down along the earth rod for its fault path.

Would you like a ladder in there?

 

[Guest77]

Yes forget the lightning rod bit it was just another thing on my mind,.

Oh thank God for that, phew, okay we can now sit down and relax.

 

[trev]

Thanks for your reply, he only did the charging point course last week and thats when he was told must use an earth rod and not the house earth. Was also told you must inform the DNO of every point you put in so they can keep a check on their loadings.

Oh bugger! Yesterday I installed a few extra sockets for an old lady and 2 outside lights for a neighbour. Best get on to the DNO then to let them know about these potentially massive extra loads then.
Who's been telling you this load of old crap mate?

 

[Guest77]

Dogwind sounds about right, or bull****, either is correct for this thread lmao

 

[Silly Sausage]

Oh bugger! Yesterday I installed a few extra sockets for an old lady and 2 outside lights for a neighbour. Best get on to the DNO then to let them know about these potentially massive extra loads then.
Who's been telling you this load of old crap mate?

WORSE!
I'm going to report you to the NICEIC and The Council.

You're going down!!!

 

[trev]

Oh please! Not the Part P Police! Anything but that! I did all the proper tests and certs and I am properly qualified!
I swear I've never stacked shelves in Tesco or any other supermarket, I've never been in IT. All I've ever been is an electrician and now I'll be dragged off for "re-education" in a gulag style training centre!
Goodbye cruel world

 

[dogwind]

Oh bugger! Yesterday I installed a few extra sockets for an old lady and 2 outside lights for a neighbour. Best get on to the DNO then to let them know about these potentially massive extra loads then.
Who's been telling you this load of old crap mate?

It was an electrician I work with a lot was on a car charging point course last week and was the NIC instructor that told them they must inform the DNO every time they install a charge point.

 

[trev]

It was an electrician I work with a lot was on a car charging point course last week and was the NIC instructor that told them they must inform the DNO every time they install a charge point.

A training course ran by the enemy. Good grief I wonder how much they stiffed your mate out of for that. Did he get a nice shiny bit of paper that he can proudly show the world and some nice stickers for his van (As you can probably tell I'm not a great admirer of NIC)
As I understand it these electric vehicle charging points are on a 32 amp supply so if we apply the same "logic" if I install a new 32A RFC in a building then I should be informing the DNO.
See what I mean about the NIC talking a load of crap?

 

[dogwind]

A training course ran by the enemy. Good grief I wonder how much they stiffed your mate out of for that. Did he get a nice shiny bit of paper that he can proudly show the world and some nice stickers for his van (As you can probably tell I'm not a great admirer of NIC)
As I understand it these electric vehicle charging points are on a 32 amp supply so if we apply the same "logic" if I install a new 32A RFC in a building then I should be informing the DNO.
See what I mean about the NIC talking a load of crap?

He isn't with the NIC he uses elecsa but it probably more a way they can keep a register of charge points so either the DNO or government can tax you for charging your car in the future.

 

[dogwind]

Dogwind sounds about right, or bull****, either is correct for this thread lmao

Oh mate you are so witty and obviously extremely funny you are wasted as an electrician when there is space for more stand up comedians. I could hardly read the writing with the tears of laughter running down my face. Keep up the good work you must be doing.

 

[HandySparks]

Who's been telling you this load of old crap mate?

ENA - Electric Vehicle Infrastructure

 

[trev]

As I say though, using the same "logic" they should be concerned about the new 32A RFCs I'm installing on Monday then.

 

[dogwind]

ENA - Electric Vehicle Infrastructure

thanks for that link mate.

 

[Guest77]

Oh mate you are so witty and obviously extremely funny you are wasted as an electrician when there is space for more stand up comedians. I could hardly read the writing with the tears of laughter running down my face. Keep up the good work you must be doing.

Cheers, I am glad you have a sence of humour, not many wanabees have.

 

[dogwind]

Cheers, I am glad you have a sence of humour, not many wanabees have.

Compared to the **** that's going on in places like Syria I don't think any of us has got much to get arsey about. Especially stuff wrote on forums. Lol

 

[Guest77]

Compared to the **** that's going on in places like Syria I don't think any of us has got much to get arsey about. Especially stuff wrote on forums. Lol

Yup very true, can't agree more.

 

[Engineer54]

ENA - Electric Vehicle Infrastructure

These ENA people are basically a lobbyist type organisation/association from what i can make of it, with absolutely no legal standing whatsoever. Yet another set-up making up it's own worthless rules!!

 

[Knobhead]

As per usual the IET weren’t slow at spotting a profit. E54 I’m surprised you didn’t mention this.

 

[Engineer54]

Yeah, .....very slow!! lol!!

It's all a bloody farce isn't it, a course on how to install a radial socket outlet, and now 55 Quid
to tell/show a qualified electrician how to install a 32A plug, or 35 quid to tell/show an IET member!!!

And this from the very people that are supposedly representing the electrical industry. The IET have been going down hill for a number of years now, ''Electrical'' isn't even a part of the new name it's given itself!! Pass the BUILDING SERVICES area of the institute including BS 7671 over to CIBSE, leave the rest to IET!!

 

[Deleted member 9648]

Thanks for your replies, its been driving me mad trying to find it written down anywhere, i also had a nic electrician telling me the other day he was told he had to do an earth bond to a lightning condutor on a house which i feel isnt right, if it did get struck by lightning then that could then travel through all the earthing into the house, and unless i am wrong i think a lightning conductor is sort of like a TT rod and you are told never to combine TNCS PME earthing to a TT system with a connecting earth!

Where are you getting this nonsense from?

Lightning conductors are an ECP and should be connected to the MET by a main bond.

Adding earth rods with a good Ra to the origin of a PME installation is a very good idea.

Just seen this thread and have to say I have never understood the requirement to main bond a lightning conductor. Yes it is an ECP but it is on the outside of the building and does not enter the zone of equal potential,being outside it is surrounded by the general mass of earth so what is the point of bonding it? I looked into this following an EICR on a church,and it seems that main bonding a LC should only be carried out with reference to other british standards,and with the advise of a LC specialist....which is beyond the scope of a 'normal' electrician. I have to say also that I have NEVER seen a main bonded LC! Now I note lack of a bond on an EICR as a code 3 and add that the guidance of an LC specialist should be sought.

 

[davesparks]

Lightning protection systems will be bonded to all exposed metalwork outside and the structural metalwork of the building, this will extend into the equipotential zone of the installation.

You will rarely see the main bond to a lightning protection system, the correct place to connect the bond is below ground level, often connected to the earth rod nearest the MET.

 

[Engineer54]

Lightning protection systems will be bonded to all exposed metalwork outside and the structural metalwork of the building, this will extend into the equipotential zone of the installation.

You will rarely see the main bond to a lightning protection system, the correct place to connect the bond is below ground level, often connected to the earth rod nearest the MET.

Lightning Protection systems should ''Always'' be bonded to the buildings MET, and as stated the connection is generally to the nearest down conductor earth rod, or in the case of a buried copper tape ring, to the nearest point on the copper tape!!

 

[Deleted member 9648]

Lightning protection systems will be bonded to all exposed metalwork outside and the structural metalwork of the building, this will extend into the equipotential zone of the installation.

You will rarely see the main bond to a lightning protection system, the correct place to connect the bond is below ground level, often connected to the earth rod nearest the MET.

Lightning Protection systems should ''Always'' be bonded to the buildings MET, and as stated the connection is generally to the nearest down conductor earth rod, or in the case of a buried copper tape ring, to the nearest point on the copper tape!!

Neither of which explains the point of bonding a lightning conductor.....yes possibly if the LC is in contact with sructural steel,but more often than not the LC's I come across could not possibly introduce an earth potential into the equipotential zone.

 

[Engineer54]

Neither of which explains the point of bonding a lightning conductor.....yes possibly if the LC is in contact with sructural steel,but more often than not the LC's I come across could not possibly introduce an earth potential into the equipotential zone.

What sort of buildings with LP systems do you work on?? You'd be surprised what a few million volts can penetrate to get to earthed metalwork inside the building or structure or even metalwork that forms part of the buildings fabric (eg.. concrete rebar/reinforcement etc)

 

[ferg]

I went to quote for a domestic after a lightning strike.

I was astounded by the damage.

The pole mounted TX was in bits all over the place.

The metal clad CU was blown to bits.

The internal fabric of the building had been destroyed by cables flapping about and bits of the roof were missing.

It was a bit unusual though.

The DNO guy attending afterwards said he'd been to loads of lightning strikes but never seen anything like it.

I got a couple of calls after the event from folks wanting lightning protection