Main earth - options?

[echoes]

Hi all,

Just moved into the new place and having a good look at the state of the wiring before planning rewire.

I have a 40 year old CU, probably the original, with the rewireable fuses. Meter is fairly new (digital type) and tails look like 25 mm2.

I will post a photo when I can get my phone connected...

The earthing arrangements are an uninsulated stranded wire connected between the CU and the main water stop cock. It may visit a gas pipe on the way, but no evidence of this so far. Certainly no earth connection to the gas pipe anywhere near the gas meter.

So what are my options: will the DNO be able to give me a TN-C-S, or TN-S earth (and if so how would i 'persuade' them?) or will I have to go down the TT route? I live in Guildford and the immediate neighbours are still using the water main for earth.

Thanks in advance...

 

[holmslaw]

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[echoes]

Untitled

• echoes
• 31 Jul 2010
• 3

Thanks holmslaw - I will contact the DNO. Certainly due for a rewire - just the measly one single per room upstairs and 7 outlets in the whole of downstairs.

 

[holmslaw]

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[echoes]

Certainly no earth provided by distributor. Earth comes out of top of CU, through garage roof space, down a cavity, under floor and connects to water main. That's it. Not what I would call safe.

 

[holmslaw]

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[echoes]

Very good, but I'd like a bit of advice on who to contact, and in what order.

I clearly need to upgrade the main equipotential bonding to current regs and connect this to the appropriate earth system, and I'd prefer PME to an earth spike.

So if I get my side of the bonding sorted, and then call EDF to install a new cut-out with PME (providing they are willing), is that the way to go?

 

[ricicle]

You could get an Electrician to put a rod and front end RCD in for a temporary measure (with possibly a disclaimer for the rest of the installation)

 

[holmslaw]

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[echoes]

Thanks Holmslaw and ricicle.

Just to clarify: is there any drawback to upgrading the main bonding (water and gas 10mm2, CU 16mm2 BEFORE calling out the DNO, since I would need to have this done anyway?

Sorry to bang on, just don't want to get into a chicken-and-egg-situation with the DNO, and to confirm that the DNO would be happy to install PME connection BEFORE leaving it to me/a spark to connect it to the main bonding and CU connection?

 

[ricicle]

The DNO will not (or should not) energise a PME installation without the correct earthing and bonding in place.

 

[echoes]

Thanks ricicle - will sort out bonding my side first.

 

[Click-Sure]

Whats wrong with TT anyway?

 

[plugwash]

It's not wrong per-se but the reliance on RCDs adds both cost and a major point of failure. Further rods absoloutely must be tested which makes installing them not a DIY job.

Therefore when encountering a household with no earth it's probably a better bet for the householder to try and get an earth from the DNO if possible.

 

[echoes]

Well I've now run 16mm2 from CU to earth block, and 10mm2 from earth block to gas and water pipes. Will call DNO to see about a PME upgrade tomorow. If they are willing, then job's a good 'un; if not then I'll get a spark to install an earth rod(s) and an RCD. Then on with the rewire...

Nothing against TT, but it just seems simpler for if the DNO can give me an earth rather than get someone knocking in rods and having to RCD-protect all circuits.