Installing an Earthing Rod

[ebee]

I don't really see what my earth rod will ever do? It, I suppose, is required so in a power cut, my RCD will still work, but the RCD sockets, are other end of house to the earth rod, it does seem OTT for 4 sockets and on FCU.

It is in real terms, a tick the box exercise, the chance that my freezers will become faulty just when we have a rare power cut seems very slim.

Not really the way I see it Eric - if you have an earth rod or not then an RCD protects agains "Earth Faults" by comparing the balance of Line(s) to N - which effectively will be some travel to earth somewhere, all the rod etc will do is to keep earthed or bonded things pretty much at the potential of the local earth of surrounds even if that local earth is a bit away from the gen mass of the earth reference of the rest of the planet.

 

[ericmark]

For an RCD to work, there must be a path for the current other than the lives (line and neutral) that path is earth, which is connected to neutral before the RCD.

If you were to take either of the wired from a shaver socket and connect it to earth the RCD supplying that shaver socket would not trip. As a shaver socket is an IT supply and has no earth.

So in the main, a generator/transformer, supplying a single item, does not really need an earth, it is likely safer not to have one, but when supplying multi-items, then we need to earth.

I have worked on a TBM with a three-phase IT supply, and it was not nice, walked around with a neon screwdriver checking any metal before touching, it seemed one phase would always connect to earth, and so you were never sure what was live, it could be you, and if you touched something earthed you would get a shock.

Made by Robin, I think a USA firm, and I was glad when the job closed.

 

[ebee]

Yes you need to have a N connected to E for it to actually be considered N otherwise its just floating, like as you correctly say, in the bathroom, you`d never get a shock because the is no earth reference cooming out of the bathroom socket.
Probably wrong to refer to them as Lives I think or phases.
I suppose you`d stick both (in single phase) as "Live" because normally they can be current carrying but none of them can be currect carrying in respect to earth, an RCD would not work on a bathroom socket unless via fault or design one the conductors becomes connected to earth.

and yes it is safer to have one transformer running one piece of equipment and no earth involved, if we could absolutely rely on that.

But one may become connected by accident therefore we connect one deliberately and protect with that in mind which has now become the safer option.

If we run appliances on TN systems using only Line and N (or Phase and N) then they will still be "Live" in respect to Earth even if there is no Earth connection to that appliance.
Any current finding its way back to E by any method will trip an RCD of sufficient sensitivity, it does not matter what route that it took but just that it took it.

 

[Munroast]

when the mains leaves my house - where would be its first proper earth likely to be
?

 

[morqthana]

Apparently if you have a mains pressure water hose that can attach to say some 12mm copper pipe (tube) then it can be helpful to water drill apparently, never tried it though, very few earth rods installed by me, I do tend to fit two at two lengths apart and then teste them seperately then join them together with a bit of 10.0 earthwire, If required I have made some conrete earth pits to suit unless I have a bought one.
Around here about 60 ohms each rod is usually achieveable and one timeonly I had to drive rods in quite diagonally not horizontally to get depth for contact before hitting hard bedrock (Malham N Yorks) .

I do have two lengths of screwable rods and a couple of couplers but never needed to use them.

Thanks. I was beginning to wonder if I'd imagined it.

 

[morqthana]

when the mains leaves my house - where would be its first proper earth likely to be
?

Where the last one before it enters your house is.

 

[morqthana]

when the mains leaves my house - where would be its first proper earth likely to be
?

No but seriously - what do you mean by "proper earth", and what type of supply do you have?