Bonding from a different aspect

[bondED]

I'm a newy here and can't find a question similar to mine, regarding incoming mains water bonding.

The usual problem; wanting to replace an old fused CU, in an old large house that has no earth bonding.

The CU and incoming water supply, which is Alkathene to Copper, are miles away from each other. Connecting the two would mean a major upheaval of floors, and recently completed decoration etc.

Why can't the incoming mains be bonded to an earth spike?

The house is served by it's own transformer via previosly overhead cables to house. These were then routed underground by electricity board. I believe the seperate earth from my CU is simply buried in the same trench.

Therefore wouldn't the proposed bonding spike be at the same potential?

 

[apprentice87]

It seems that you do not know the difference between earthing and bonding and the reason for them in the first place....

This being the case you should not be changing a CU.....

john...

 

[Sharpend]

Just to be clear, are you saying that the property is currently on a TT earthing arrangement?

 

[steptoe]

I dont think he knows what he is saying sharpie,

either that or he is just a very bad troll.

 

[ADS]

I'm a newy here and can't find a question similar to mine, regarding incoming mains water bonding.The usual problem; wanting to replace an old fused CU, in an old large house that has no earth bonding.

The CU and incoming water supply, which is Alkathene to Copper, are miles away from each other. Connecting the two would mean a major upheaval of floors, and recently completed decoration etc.

Why can't the incoming mains be bonded to an earth spike?

The house is served by it's own transformer via previosly overhead cables to house. These were then routed underground by electricity board. I believe the seperate earth from my CU is simply buried in the same trench.

Therefore wouldn't the proposed bonding spike be at the same potential?

You are not trying to get your incomming water at the same potential as your system (supplied) earth - that would be earthing.

You are trying to get any 'extraneous' metalwork, (e.g. your incomming water), at the same potential as the house 'installation' CPCs, should there be an earth fault condition .

Therefore, it is bonded to the MET, where all your CPCs and Bonding conductors are connected. The fact that this MET is connected to your 'means of earthing' is besides the point.

 

[paul b b]

I dont think he knows what he is saying sharpie,either that or he is just a very bad troll.

i think steps, thats hes saying that the earthing conductor is in the ground so why cant he bond the water to a rod aswell, insted of taking it back to the MET as in affect they are connected in the ground. though im prob wrong as usal lol

bondED, no you cant, you need totake the bonding back to the MET, end of im afraid. in the past i have taken bondings around the outside of the property to save ripping apart the inside, if you run it low level it can be conseald by plants etc..

paul

 

[Technician]

Repeating Apprentice 87's post; earthing is one thing.

Bonding is another.

If the supply is now buried in a trench, do you know

where your earthing conductor is located?

If the supply IS a TT system, this will have an impact

upon your choice of protective devices.

Steps will enlarge upon this I am certain.

 

[Steve3948]

I'm under the impression that if the DNO go underground they have to TNC-S or PME the supply.

Well that's what SSE say anyway.

 

[Doc Hudson]

Regulations are quite clear about how and what has to be earthed and/or bonded. The decoration has no relevance to the essential safety requirements. Thread moved.

Doc H.

 

[Technician]

Yes Steve, and there should be a label indicating

PME at the head.

Can we have a few pics of the arrangements at the

existing cut-out? (if there is one)

 

[Andy™]

Why can't the incoming mains be bonded to an earth spike?

thay can be connected to a rod

but it must be the same rod that the rest of the installation is connected to... but thats assuming its TT.

 

[binky]

the question is - does the copper water piping introduce an earth potential to the property? or is it electrically separated from earth by plastic piping?

 

[bondED]

Sorry have been away for a few days. Thanks for responses.

Now had a chance to look closely at system. Have discovered that the cable from the earth rod under the meter box is cut off below ground. Probably done when the overhead supply was put underground.

So it's not a TT system, more likely TNCS. The main earth is provided from the Neutral at the supply fuse and fed directly to the consumer unit. There is no double pole isolator and no MET in the meter box and as stated before no bonding that I can find.

Suppose I have to talk to the supplier about isolation before I invite an electrician to replace the consumer unit, unless he likes working live!!

On the issue of bonding; the water supply is plastic into the house then to copper. Rather than disturbing the whole house, I'll take up Paul's suggestion (Thanks) of routing bonding outside the house, but probably in conduit.

Once again, thanks for the help.

 

[Apache]

If the incoming water is in plastic pipe there may be no requirement to bond it.