Earthing system - as installed in a 1940s house

[olddog]

My background is in SCADA systems - I'm not a sparks - this is why I'm taking up space on your forum with such a basic question as this :

I have become involved with a rural house built in the late 1940s

Supply is two wire, overhead from a pole mounted transformer around 300M away
Internal wiring would appear to be mostly original !

The only service entering from below ground is water. There is some evidence of earth bonding to water pipes. The attic located water tanks are made of plastic.

At the fuse boad N and E are commoned ( is this a normal arrangement in domestic houses ? )

There is no evidence of an earth spike

In the medium term a total rewire would be in order

My concern is, in the short term, is this safe ?

What, for instance, if the supply neutral wire were to be damaged ?

What is your view ? & what ( if any ) modifications would you make ?
　
Olddog

 

[olddog]

Great info, thank you all.

Putting in a new earth rod will hardly do any harm so ( even if one is already installed somewhere or other )

In the context of ESB norms, are N + E to be linked or are they separate with E going direct to rod ?

16 Sq OK for earth rod link ? ( std rural 1p supply )

Olddog

 

[Eggster71]

16mm is more than adequate.
As you have no earthing for the lighting circuits I'd be tempted to install a couple of RCD incomers, one for the main box and one for the "new" box. That way if one tips you'll not lose all your power!
Your only problem will be if you have any existing earth faults!

 

[jimsky007]

Hi

If you have a TT supply coming in (2 wires) you will need to put a spike into the ground and get the Ze below 200ohms
You have to fit and rcd 100Ma or 30Ma time delay to the main incomer and all socket outlets will require a 30Ma rcd to protect them.

If you have a PME (TN-CS) you can check by doing a Ze test across the incoming supply if you read less than 0.35 its a TN-CS then it would be ok to have the N & E common at the origin of the supply but you still have to run 3 wires to your sub circuits

 

[Spudnik]

The supply authority DO NOT permit self PMEing.

However, yes, you could test and confirm at the incomer to check the Ze before you contact them so that they can come out and provide a MET, which sometimes is FOC.

 

[Guest123]

30Ma time delay

No such beast I'm afraid...

 

[martinxxxxxx]

No such beast I'm afraid...

I think there is a market for one. Why has no one filled it?

 

[olddog]

The great thing about electric standards is that if you dont like one standard there are always several others to choose from !

This thread illustrates the point

Are European neutrals multigrounded? - ECN Electrical Forums

Meanwhile, guess I need to have a look at

National Rules for Electrical Installations, Third Edition, ET101, Figure 2A

Anyone know if this is up on the web ?

Olddog