Earthing Requirements...Conflicting Advise

[unlucky]

Guys,

I'm looking at having / doing a re-wire in our house and have been speaking to a few electricians who are willing to advise, check while all chases are exposed and floorboards are up, recomend changes and finally sign off.

I've been researching and reading and am not a complete novice but when it comes to the earthing side I'm at a bit of a loss.

The two sparkies i've spoken to have both said different things. Our current set up is;

An old cast iron main fuse
No earthing running from that to the CU
Earth bonding to the gas main (2mm!!)
NO (I know it seems impossible) water stop tap coming into the property. (I've lived here for 2 years and have raised all floorboard in all likely and unlikely areas and have turned up nothing!

The conflicting advise;

1st sparky said not a problem, 10mm earth to both gas and water (if he finds it) and what ever happens on the supply side of the CU doesn't matter (?!)

2nd sparky said I would need to have the provider change the isolator fuse with an up to date unit which would bring in earth which would be utilised along with the 10mm earth to water and gas.

Who is right? I've been waiting a good while for the main fuse to be changed and don't want that to be the thing that stops all the work to the house going ahead if it doesn't have to just because the provider doesn't really care!!

Is this an area that is open to interpretation? It doesn't look like it according to the reg's and rules around earthing but I'm not an expert and want something installed that will be safe.

Any advise would be much appreciated.

 

[ricicle]

The gas and water need bonding, if no stop tap comes to light then within 600mm of it entering the property.
A new cut - out may be in order, it may be worth you or a sparky to contact the DNO to ascertain your supply type and for the sparky to do a Ze test possibly to the cast iron cut-out at least. That said there should be some sort of earthing conductor to your DB. Sometimes they were just small twisted unsheathed wires from the cut-out to the board.

 

[Chri5]

A TT system has no earth from the suppliers head, but requires a earth rod and an rcd front end.

Since the supply is old and the head needs a change you should ask the supplier for an earth. If you are in the middle of nowhere then you won't get one and might be forced to adopt TT.

If you live in a place with some housing density you will.

Water and gas need bonding. Unless the water is PVC pipe I'd go with turning off the supply and commissioning a plumber to provide a water stop point in the house. Then you have a point to bond to and more importantly a sensible off point.

If the cock gets fitted sub floor void get one of these http://www.plumb-warehouse.co.uk/ishop/968/shopscr492.html which allows switching.

 

[unlucky]

I'm not putting any great faith in the supply company changing the isolator fuse any time soon...its been a while and the are 'getting round to it'!

If I install / have installed an earthing rod with this being on the CU side of the supply does this break any rules? also, if the supplier ever comes and changes the fuse does this effect the integrity of the system if the earth is not used as the earthing rod is carrying out its job?

As I said above, don't want to leave it in the hands on the meter company!!

Thanks for the speedy responses!

 

[RF Lighting]

Are you sure you've asked for the head to be replaced or a PME upgrade? My DNO will do this within 6 weeks if it's a routine job, and within 24 hours if you know what to say on the phone

I'd only use a rod as a last resort.

Can you post a photo of the existing cutout and earthing arrangement for us to have a look at?

 

[unlucky]

I'll give them another ring and try someone else, its always luck of the draw with call centers! Any advise on the correct terms to use would be helpful.

I'll aim to get some photos up tomorrow, I'm going to bed now though!

Thanks again.

 

[JACKC]

Just ring them again and tell them you can hear something fizzing and can smell something burning. They might come a bit quicker. That might be what what RF means of knowing what to say.

 

[unlucky]

Thanks,

I'll give that a try at dinner and see what is said.

The location of that main isolator fuse is about 6 meters from the CU (i know thats outside of reg's!) Another question is if they change the earthing system from TT to one of the others am I OK running a 16mm earth cable from there to the earths on the gas and water and back to the CU??

Gas is next to the CU, water as mentioned is currently missing in action!

 

[unlucky]

WELL!!

Turn up for the books, said there was a slight burning smell, and that the pitch inside it was leaking out(slight embelishment but im entitled after this dragging on for 18months!)

They are coming to change the fuse type this eve and the guy from yedl said all I have to do is run a 16mm earth from the CU to the isolator fuse then apply for a pme connection for the earth to be connected up. Is this right?

Thanks everyone for your advice.

Phil

 

[bongos]

They are coming to change the fuse type this eve and the guy from yedl said all I have to do is run a 16mm earth from the CU to the isolator fuse then apply for a pme connection for the earth to be connected up. Is this right?

It sounds like he will be providing you with PME when he comes round. As stated, have your 16mm² green/yellow ready connected to the CU for him and your 10mm² bonding to gas/water in place.

Hopefully your problem will be sorted and you will have PME FOC if you are lucky, Unlucky...

 

[Guitarguy]

I don't understand how the guy from YEDL can say that until he has done a ELI test on the new cutout! For all he knows the ELI at the point of supply could be above limits (.80 ohms i expect seeing as it's a SNE supply).

 

[bongos]

I don't understand how the guy from YEDL can say that until he has done a ELI test on the new cutout! For all he knows the ELI at the point of supply could be above limits (.80 ohms i expect seeing as it's a SNE supply).

If the Ze was above limits would then wouldn't he say no to TN-S, instead supplying PME if it was available? Is it definitely TN-S anyway as at the moment there doesn't seem to be any earth to the CU from the cutout.

Is SNE the DNO term for TN-S?

 

[unlucky]

Its not TN-S currently. Its TT. They came and changed the fuse but said I would need to book in for a pme upgrade once the electrics within the property was up to standard.

I presume by this he means correctly bonded etc. He said he looked at the plans before he came and there isn't an earth supply coming into the property

but then said if I run a 16mm earth to the fuse the PME upgrade would consist of connecting that earth to the supply side neutral so why would I need the road digging up along with my garden?!!

Anyway, for now its up to scratch and the re-wire can be carried out with the PME booked in at a later date provided the 16mm earth line is run from the earth block so it can be connected up by yedl.

They are still going to charge me though!!

Thanks for all your help guys, managed to get a 2 year problem sorted in less than a day!!

Phil

 

[Guitarguy]

I don't understand how the guy from YEDL can say that until he has done a ELI test on the new cutout! For all he knows the ELI at the point of supply could be above limits (.80 ohms i expect seeing as it's a SNE supply).

If the Ze was above limits would then wouldn't he say no to TN-S, instead supplying PME if it was available? Is it definitely TN-S anyway as at the moment there doesn't seem to be any earth to the CU from the cutout.

Is SNE the DNO term for TN-S?

Yes, SNE is the term for TN-S, It stands for Seperate Neutral Earth. [/b]

 

[unlucky]

just had a look at the new main fuse, and have noticed that the guy didn't put the wire security tags on the main fuse...

any comments from anyone on my last question about what im getting by paying for a pme upgrade if all that happens is the 16mm earth is connected to the incoming neutral?!