Earthing Spike

[bernardgreen]

The earth stake becomes a saviour should there be a open Neutral fault in the local distribution network which leaves the property with it's CPC ( Earth wiring ) with no connection to earth. When the incoming Neutral is not connected all the Neutral and Earth wiring in the property can drift up to Live by capactive coupling, any appliance or lamp that is switched on will provide a low impedance path to force the Neutral and Earth ( CPC ) up to Live potential.

 

[securespark]

This is mainly a note to future visitors to this thread but the only thing to be wary of with a TT > PME conversion is to make sure the gas and water pipes (and any others) have correctly sized PEB's.

 

[RF Lighting]

The earth stake becomes a saviour should there be a open Neutral fault in the local distribution network which leaves the property with it's CPC ( Earth wiring ) with no connection to earth.

the chances of this happening are so incredibly small it really isn't worth worrying about.

When the incoming Neutral is not connected all the Neutral and Earth wiring in the property can drift up to Live by capactive coupling, any appliance or lamp that is switched on will provide a low impedance path to force the Neutral and Earth ( CPC ) up to Live potential.

An earth stake will not prevent this.

 

[JohnW2]

The earth stake becomes a saviour should there be a open Neutral fault in the local distribution network which leaves the property with it's CPC ( Earth wiring ) with no connection to earth.

the chances of this happening are so incredibly small it really isn't worth worrying about.

Quite so, and in the (even less probable) event of the 'worst possible network neutral fault' (the type which leaves one incoming neutral connected to several other consumers' installations, but not to tranny or earth), an earth electrode would make little difference, anyway.

Kind Regards, John

 

[securespark]

Above 200 ohms is considered unstable.

I'm above 200Ω.

 

[bernardgreen]

I'm above 200Ω.

200 ohms with 35 mA flowing through it creates a difference of 7 volts between top of rod and the surounding ground. So quite safe. The RCD will ( should have ) tripped before the current reaches 35 mA

With a 100 mA trip RCD the voltage might reach 20 volts before the RCD ( 100 mA ) trips. Again reasonable safe.

 

[securespark]

Sorry, Bernard. I have a TN-S supply.

I was trying to be funny. Failed again!!

 

[bernardgreen]

Sorry, Bernard. I have a TN-S supply.

Maybe I am a bit too obsessed with the problems of earthing / bonding / grounding to see anything connected with them as humerous, ( pun not intended )

There was conductor who was perfect in his work, the best ever employee the bus company had employed. But he had to live and sleep in a bus at the depot. The perfect conductor was ohmless. sorry

 

[PTS2]

The earth stake becomes a saviour should there be a open Neutral fault in the local distribution network which leaves the property with it's CPC ( Earth wiring ) with no connection to earth.

the chances of this happening are so incredibly small it really isn't worth worrying about.

When the incoming Neutral is not connected all the Neutral and Earth wiring in the property can drift up to Live by capactive coupling, any appliance or lamp that is switched on will provide a low impedance path to force the Neutral and Earth ( CPC ) up to Live potential.

An earth stake will not prevent this.

A failure in the network is as you say not worth worrying about, but it's still got more chance of killing you than capacitive coupling in your house wiring!!

Just because a piece of metal is at 230 volts wrt ground doesn't mean it's dangerous. If electricity worked that way then people would be dropping dead when they shook hands and one of them had recently been walking on some static inducing carpet!

 

[ericmark]

Sorry, Bernard. I have a TN-S supply.

Maybe I am a bit too obsessed with the problems of earthing / bonding / grounding to see anything connected with them as humerous, ( pun not intended )

There was conductor who was perfect in his work, the best ever employee the bus company had employed. But he had to live and sleep in a bus at the depot. The perfect conductor was ohmless. sorry

We have one man buses so are the drivers Semiconductors?

 

[PBC_1966]

The earth stake becomes a saviour should there be a open Neutral fault in the local distribution network which leaves the property with it's CPC ( Earth wiring ) with no connection to earth.

the chances of this happening are so incredibly small it really isn't worth worrying about.

Rare, but certainly not unknown. Where I used to live (rural Norfolk) I can recall two instances of neighbors asking me to "take a quick look" when they lost power and when I tested I found an open supply neutral. One was TT as I recall, but one had been converted to TN-C-S.

 

[PBC_1966]

It is far better to leave it in. In fact most of the rest of the world requires a customer's electrode with a TN-C-S supply, and rightly so.

Indeed, it's required here. It's connected directly to the incoming supply neutral, most often either where it passes through the meter base or to the neutral bar in the main distribution panel.

I know TN-C-S is the norm in the R.o.I. Is the electrode also standard there?

 

[JohnW2]

It is far better to leave it in. In fact most of the rest of the world requires a customer's electrode with a TN-C-S supply, and rightly so.

Indeed, it's required here. It's connected directly to the incoming supply neutral, most often either where it passes through the meter base or to the neutral bar in the main distribution panel.

Presumably the earth electrode is of limited value in a TN-C-S installation with a 'lost neutral' if it is (as you imply) connected upstream of any RCD(s). It only takes a "~1A load" to be switched on for the potential of a 50Ω electrode (hence CPCs and exposed-c-ps) to rise to ~50V above true earth, and larger connected loads could have the potential rising to close to line potential. Of course, given proper bonding (i.e. a proper equipotential zone) having high potential exposed-c-ps "should not" usually matter, but I can't see that the earth electrode would do much to mitigate it (unless absolutely every load in the installation were 'switched off').

Kind Regards, John

 

[securespark]

I was trying to be funny.

At least JohnW got it!

 

[JohnW2]

I was trying to be funny.

At least JohnW got it!

I did indeed

Kind Regards, John