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earth or girth?If he gives me a good earth I'll have a go!
Discuss no earth in the UK Electrical Forum area at ElectriciansForums.net
earth or girth?If he gives me a good earth I'll have a go!
Just a bit of information picked up today, just finished a new build in the middle of nowhere and had supplier out to provide new supply, all overheads so presumed I would need earth rods, all installed ready, engineer turned up dropped an earth loop on and stuck a cut out with earth terminal, when questioned on this he said as long as they get a reading less than 0.4 ohms they automatically put a cut out with earth terminal. Not sure if this is everywhere or just regional. Waste of earth rods and time but will know better next time.
yep...better than just relying on extranious should the neutral go floating...Wrong!! it was a very worthwhile, and certainly not a waste of time on your part!! It is always a good idea to have a local earth rod on a PME earth connection, especially if it's around the 20 ohms mark!! Many European countries insist on a local earth rod at all PME supplied installations!!
When I tested my home installation a few weeks ago out of curiousity I found the Ra to be fairly pants (by which I mean 'not good', not a pair of pants buried and connected to the earthing conductor, like GlennSparks tractor engine) around 120 ohms, but with all the bonding (gas and water) and the bent copper pipe with an earth connected to it, I got 0.something ohms instead. I know technically I should try to get the twig itself a bit better, but with a reading like that I'm not sure I'll bother! One day I will test the bent copper pipe that is hammered into the ground under the house on its own and see what reading that gives.
Hmm, maybe I'm doing something wrong. As I'm at a bit of a loose end this morning I think I'll have another go.Your down to less than an ohm on your bonded pipe work?? lol!! Sorry i find that extremely hard to believe, in fact i'll go as far as saying, i don't believe it!!!!!!! So why is your earth rod only giving you an Ra of 120 ohms??
Hence the 'ME' part of PME.It is always a good idea to have a local earth rod on a PME earth connection, especially if it's around the 20 ohms mark!! Many European countries insist on a local earth rod at all PME supplied installations!!
Ok, just done another test, and here are my results. Please tell me if I am doing something wrong.Your down to less than an ohm on your bonded pipe work?? lol!! Sorry i find that extremely hard to believe, in fact i'll go as far as saying, i don't believe it!!!!!!! So why is your earth rod only giving you an Ra of 120 ohms??
Your down to less than an ohm on your bonded pipe work?? lol!! Sorry i find that extremely hard to believe, in fact i'll go as far as saying, i don't believe it!!!!!!! So why is your earth rod only giving you an Ra of 120 ohms??
Ok, just done another test, and here are my results. Please tell me if I am doing something wrong.
Measuring Loop impedence L->PE with my probes on the tails going into the RCD for L and N, and the PE croc clip on the rod's earth cable disconnected from the MET I get 134 ohms. I put this bad reading down to it being an ancient thin twig you I can easily pull in and out of the ground by hand, and what looks like a very old 4mm earth conductor.
Measuring as above with the PE croc clip on the bond cable (which remember also has the buried copper pipe on it), I get 0.35 ohms (PFC 574A). I put this down to the copper in the hard clay earth underneath the house, metal gas pipe buried in the earth, and the fact that I am about 200 metres from the transformer. (just walked to the transformer and it is 173 paces with my little dwarf-legs )
hmm...well lets face it des...he should know that relying on extranious to bring down external loop isn`t on is itIts a long thread to read the full story
You have a high reading on your rod and have metal service pipes which gives a low Zs when connected
I know you say the transformer is nearby,is next door Pme ?
stroppy...what is it exactly your trying to acheave here mate?My gas pipe is definitely straight in the ground, as I can see it - its an ancient iron/steel thing that disappears into the earth. Anyway, I disconnected the bond from the gas pipe and still got 0.46, but then it ocurred to me: as the pipe is connected to appliances which have their metalwork earthed, am I not getting a parallel path through their CPC's? I'm not going to the trouble of disconnecting those, or the bonds on the water pipe or central heating as they are under the floor and a pain in the arse to get to. I'm getting more confused about this by the minute!
The more I think about it I think it is the gas service, as (a) it is a metal pipe going straight into the ground, and (b) the gas-main in the road goes right past the transformer within about 2 metres of it.
Testing the MET without the twig got me 0.35.
I'm not relying on it, I and E54 are just curious as to how it manages to be so low, and yes I know about parallel paths and the purpose of Ze thank you.hmm...well lets face it des...he should know that relying on extranious to bring down external loop isn`t on is it
we know this happens due to parallell paths but he should know the whole idea of doing a Ze in the first place...
if he cant fathom that one...then he`s no business testing ...has he...
how did you guess?...the cable ends were a bit scratchy mind on the way out but...I'm not relying on it, I and E54 are just curious as to how it manages to be so low, and yes I know about parallel paths and the purpose of Ze thank you.
As for can't fathom and no business testing, I presume you knew all about Zs Ze Ra parallel paths and testing as soon as you popped out of the womb, did you? No, you learnt it, which is what I'm doing.
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