Exterior socket on PME system

[happysteve]

It's RCD protected...

It's solving the problem of a lost neutral on the DNO side.

Even then an Ra of 3.35 isn't a huge effort.

I'm confused. Surely an RCD won't help for additional (shock) protection when there's a missing PEN (on the DNO side)? Current flows out through the L, through the RCD, through the load, back through the N, same current back through the RCD (so, balanced), to the PME block (where earthing conductor is connected to PEN), to MET and through CPC to exposed conductive parts, through body of person, to earth.

I agree that having an earth electrode with good Ra is better than not having one (for PME) to reduce the touch voltage in the event of loss of PEN on the supply side. To remove the shock risk requires a very low Ra, and something like 3.35Ω, depending on the local ground conditions, may be... challenging.

 

[Bobster]

Draw it out Steve, the N>E link is before the RCD, so current flowing down the PE will not go through the RCD causing an imbalance.

 

[Midwest]

Are you both not saying the same thing?

 

[hightower]

On quickly reading and passing through, I've got to agree with happy steve.

Scenario: Class 1 appliance, no faults present anywhere on installation except broken neutral on PEN conductor. Current is balanced through RCD, earthed conductors rise to a dangerous voltage, link between Class 1 appliance and earth made via a person, RCD is going to say "hey, this looks alright to me"

What am I missing?

 

[Midwest]

Don't know, my understanding, limited as it is, is broken PEN conductor, is your worst case scenario (don't have nightmares folks) RCD or no RCD.

 

[South Spark]

Realistically the place has metal pipework disappearing underground that will have a lower resistance than any bit of copper I could bang into the ground.

 

[hightower]

Realistically the place has metal pipework disappearing underground that will have a lower resistance than any bit of copper I could bang into the ground.

Which you can't utilise in your design of this addition.

 

[soulman]

Hi, An Ra of 3.35 is not easily achievable. I have had 6 rods in the ground & managed 20 ohms

 

[Midwest]

It's remarkable how some threads go off on a

 

[soulman]

Apologies, I was just surprised at that comment.