TT: A bit of guidance please

[davesparks]

Don't put it right next to the wall!

 

[Engineer54]

First off I am not your matey and wouldn't want to be I based my opinion of you and the others mentioned not only after your comments to my post but on others I have read on this forum over the past 6 months.

I have read my posts made in this thread and still claim I have never said 200 ohms is an acceptable value for any TT installation if you want to use my reference to BS 7671 to try and justify your behaviour towards me then why don't you just refer to 1667 ohms also mentioned in BS 7671 which in theory is the maximum.

If you think any customers are willing to pay an electrician to mess around trying to achieve an Ra to gain ZS values which may never be achievable you are mistaken not in my part of the world where TT is the dominant method. If you have a two up two down mid terraced property supplied by overhead no PME with a tarmac pavement at the front and a 6 inch concreted yard at the rear you are limited to where rods or other methods can be used you do your best to achieve the lowest Ra you can in a timely fashion.

Oh for sure your not my mate ha ha, Eh, i don't think the term was used in that context to mean anything along those lines.... I speak as i find, and you come across as someone who is only interested in the ''Easy'', ...i may be wrong but that's how you come across, especially when you throw your toys out the pram and call start calling people that have proved no-end of times that they know what they are talking about, ...Bell Ends!!

If and only if the RCD device works as required (they are not exactly the most reliable bits of kit), if it doesn't it won't matter a jot what the maximum Ra ohms is in theory or otherwise.... Hence why is is prudent to always fit an up front S type RCD devise, at least you are giving the TT installation a decent degree of protection, rather than Zip!!

I would expect customers hope that an electrician employed to do a job of work that involved their safety to do just that. I agree it isn't always achievable but i'm sure they would expect you to at least do your up most to TRY!! 6'' depth of concrete in a back yard isn't an excuse not place a decent sized rod DEEP!! After all your going to need to provide a flush concrete or tough plastic earth connection pit anyway, or is that something else you don't provide, because it's not a viable proposition for a customers two up two down terraced house??

 

[uksparks]

Don't put it right next to the wall!

No it's ok I won't, I was just saying the existing one is next to the wall. I spoke to Trev and said put it a clear meter away from a wall min, which is a good idea, I need to have a look to see where I can get one in and see where's best.

I do appreciate all the advice given.

 

[7029 dave]

UK, have not read the whole thread, if it is an main earth protective conductor, run it in 16mm, I would agree with you.

 

[Gavin A]

No it's ok I won't, I was just saying the existing one is next to the wall. I spoke to Trev and said put it a clear meter away from a wall min, which is a good idea, I need to have a look to see where I can get one in and see where's best.

I do appreciate all the advice given.

this is probably going to be obvious, but really check for services before banging an 8 foot spike into the ground, as water pipes and drains etc are only at about 4 foot, and it can really ruin your day to put a spike through one of them.

 

[Engineer54]

this is probably going to be obvious, but really check for services before banging an 8 foot spike into the ground, as water pipes and drains etc are only at about 4 foot, and it can really ruin your day to put a spike through one of them.

Where accessible it's always advisable to excavate a down metre, before driving the rod(s) in the ground if there is a possibility of pipes or drains in the vicinity. Also makes setting in the flush earth connection pit that much easier too!! lol!!

 

[Gavin A]

Where accessible it's always advisable to excavate a down metre, before driving the rod(s) in the ground if there is a possibility of pipes or drains in the vicinity. Also makes setting in the flush earth connection pit that much easier too!! lol!!

I was going to say that 1m wasn't far enough, but thought I'd check, and apparently it's actually 750mm minimum depth for water pipes in England at least. I'm sure I remember being told it was 1200mm, but that might have been Scotland, as I can imagine in Inverness or somewhere 750mm isn't going to protect from winter ground freezing.

When I was doing festivals, one of the stage crews put a spike through the mains water pipe that just happened to be running randomly through the middle of a field without the farmer even knowing anything about it being there. Not what I wanted to see on the morning before we opened, a sodding fountain slap bang in the middle of the front of the main stage.

Been a bit paranoid about it since then.

 

[ipf]

I was going to say that 1m wasn't far enough, but thought I'd check, and apparently it's actually 750mm minimum depth for water pipes in England at least. I'm sure I remember being told it was 1200mm, but that might have been Scotland, as I can imagine in Inverness or somewhere 750mm isn't going to protect from winter ground freezing.

When I was doing festivals, one of the stage crews put a spike through the mains water pipe that just happened to be running randomly through the middle of a field without the farmer even knowing anything about it being there. Not what I wanted to see on the morning before we opened, a sodding fountain slap bang in the middle of the front of the main stage.

Been a bit paranoid about it since then.

'Singing in the rain', eh? or 'Three coins in the fountain', maybe.......shouldn't have been much trouble sinking the rod, at least.

 

[Gavin A]

'Singing in the rain', eh? or 'Three coins in the fountain', maybe.......shouldn't have been much trouble sinking the rod, at least.

twas a 5 foot marquee peg to guy the stage cover down.

 

[Engineer54]

I was going to say that 1m wasn't far enough, but thought I'd check, and apparently it's actually 750mm minimum depth for water pipes in England at least. I'm sure I remember being told it was 1200mm, but that might have been Scotland, as I can imagine in Inverness or somewhere 750mm isn't going to protect from winter ground freezing.

When I was doing festivals, one of the stage crews put a spike through the mains water pipe that just happened to be running randomly through the middle of a field without the farmer even knowing anything about it being there. Not what I wanted to see on the morning before we opened, a sodding fountain slap bang in the middle of the front of the main stage.

Been a bit paranoid about it since then.

The way housing estates etc are thrown up these days in the UK, i'm pretty sure that 90%+ are nowhere near 750mm deep unless as you say the area is subject to long winter periods of 0 C degree and below!!. Anyway excavating down a metre will certainly help the overall Ra and stability of any earth electrode system. Oh, and don't expect the initial Ra value obtained to be it's final value. As the backfilled soil compacts against any exposed electrode, Ra values should fall, sometimes quite significantly...