PME head , builder forgot earth cable , 100amp 3phase supply , 10 bedroom house , 10 bedroom house

[ipf]

Looking at the size of the job, get it dug up and done properly.
Builder's fault...he carries the can.

 

[Pete999]

Looking at the size of the job, get it dug up and done properly.
Builder's fault...he carries the can.

See the original post "as I directed" if the OP has instructed the builder what to install, I can't in all honesty see how it would be the buider's fault, the OP told the builder what to do, so down to the OP imo.

 

[ipf]

See the original post "as I directed" if the OP has instructed the builder what to install, I can't in all honesty see how it would be the buider's fault, the OP told the builder what to do, so down to the OP imo.

''the builders installed a 35mm 4core swa as i directed however they forgot about a 16mm earth''.
Are we getting the full facts, Pete?

 

[Pete999]

''the builders installed a 35mm 4core swa as i directed however they forgot about a 16mm earth''.
Are we getting the full facts, Pete?

True, good point, did matey mention the 16mm2 earth? only he can tell so come on OP spill the beans, did you or didn't you instruct the builder to install the earth wire?

 

[andysparkfree]

yep, however they supplied the cable , my input was instruction only, so as long as it is correct to the regs I'm now happy

 

[westward10]

The armour of that cable is inadequate to support main protective bonding.

 

[Pete999]

yep, however they supplied the cable , my input was instruction only, so as long as it is correct to the regs I'm now happy

Agree, but what were your instructions exactly? did you tell them to run the SWA and an earth cable?

 

[andysparkfree]

yes 35mm swa 4core and 16mm earth was the instruction

 

[Pete999]

yes 35mm swa 4core and 16mm earth was the instruction

Their cock up then

 

[Octopus]

yes 35mm swa 4core and 16mm earth was the instruction

I think you are brave not to be there at the relevent time to avoid this happening ................ so how did this happen, especially if its under a finished "surface"?

 

[Octopus]

Their cock up then

I wonder how this was comunicated? and to who?

 

[andysparkfree]

i actually had no idea they was going to run the cable when we wasn't on site , i just gave them the list to get on site , other than that the removed and replaced a large section of the block paving and slabs
they did well considering how busy that part of the job , just a shame they didn't get it completely right lol

 

[Octopus]

i actually had no idea they was going to run the cable when we wasn't on site , i just gave them the list to get on site , other than that the removed and replaced a large section of the block paving and slabs
they did well considering how busy that part of the job , just a shame they didn't get it completely right lol

So its not their fault then..................

 

[andysparkfree]

so if i tell you that we need a 35mm swa and a 16mm earth run in for the mains , and you only run a 35mm swa and forget the earth even though theres an email trail then I'm guessing its your fault ...... or is it just me

 

[Octopus]

so if i tell you that we need a 35mm swa and a 16mm earth run in for the mains , and you only run a 35mm swa and forget the earth even though theres an email trail then I'm guessing its your fault ...... or is it just me

So what exactly did the email say?

You previously said you gave them a list of what to get onsite ....

My experience of builders leaves me in no doubt, spell it out AND check they understand - and sometimes it'll still go wrong - the only way to avoid issues like this is to supervise/help on the day.

 

[andysparkfree]

i think i started my original question by stating that the builder forgot to run the earth cable , trying to gage a easy result in solving the issue, be it by earth rod or if the builder needs to dig up the road/ earth again.
the builder him-self was the one on my last site visit to show me that his men forgot to run the earth , i confirmed to him ill do some homework and see if its a big issue or if theres an easier route

didn't realise idd have to remember word for word of emails (i do a few ) to provide as evidence ????

and the fact they undertook the works between us on site (1st fix that took 3 to 4 weeks) and our planed return to site to start 2nd fix is just unlucky but i guess worked with there plans

moving on , its now proven that the swa braid is correct for the required bonding earth size so all and all no issues

no blame needed, was about solving an issue , which has been sorted

 

[westward10]

I disagree, the armour is not adequate.

 

[andysparkfree]

whys that ?

I'm only quoting what the NICEIC told me via phone conversation

 

[westward10]

If they told you the armour of that cable is adequate to support bonding they are incorrect.

 

[andysparkfree]

please explain ?

 

[Ian1981]

If your protective bonding conductors require to be sized 10mm copper minimum then if you intend to utilise the armouring of the swa then the sizing must be equivalent of 10mm copper as an example an 85mm steel conductor would meet this requirement as the copper to steel ratio would be 8.5 as referenced in GN8

 

[westward10]

I would like to know where the NICEIC got 84mm from as this goes against GN8 which quotes 79mm and from manufacturers spec I have looked at none are quoted at 84mm.

 

[123]

Have you got it in writing from the NICEIC Helpline that the SWA is adequate for bonding?

Are they also prepared to stand over their calcs if the s**t hits the fan?

 

[andysparkfree]

found this online

 

[andysparkfree]

I'm hopping your wrong , but would be great to be sure either way
I've got a few days before I'm back on site , so time to make sure I'm clear on how to proceed

 

[Wilko]

My GN8 lists 4x35mm swa cable as having 78mm of steel, which is close but no banana. It may be your particular cable has more steel or a better conductivity than average, so it might be worth checking with manufacturer's data for that specific cable?

 

[Ian1981]

Even if it’s 84mm
84/8.5= 9.88
So it’s still under 10mm tho it’s dam close and maybe nitpicking a bit.

 

[andysparkfree]

you guys really know your stuff !!

 

[EbolaSideRoom]

1) I agree with the early post - never trust a third party with this aspect of the installation. It doesn't matter how good we are as installers if the supply is f****d.
2) I'd be inclined (if there really is no possibility of adding an additional Main earth to take advantage of the PME conditions available) to do as Westward10 suggests.
3) If, however the ferret/ terrier/apprentice can be trained to do their duty and get the extra cable installed then surely 16mmsq.csa isn't big enough anyway?

 

[KEV 1 N]

It seems you may be able to get away with using the armouring as your earth conductor, however I don't mean to put doubt (or possibly more doubt) but if the outer plastic sheath has any damage (from sharp stones) moisture may get in and over time and rust, so the conductivity will be reduced. Did the builder lay the cable in a bed of sand, or just back fill with what they dug out?

 

[westward10]

That Table is not for thermosetting which I suspect yours is but I must admit I don't know if this is a factor. What was it you asked the NICEIC.

 

[ipf]

you guys really know your stuff !!

No doubt, but, as said previously, with such a job, which is obviously important and could have a major affect on future work, I wouldn't be taking any chances. Get the job spot on...dig?

 

[westward10]

Even if it’s 84mm
84/8.5= 9.88
So it’s still under 10mm tho it’s dam close and maybe nitpicking a bit.

I always use 8.8 as it allows discrepancies of the armour make up between manufacturers.

 

[KEV 1 N]

I once came across a 95mm 4 core SWA (installed 2007) where which was ran underground in a duct from a substation, ran downhill to a building. Where it was glanded into the section board was completely corroded as were the SWA armouring strands, could only presume the outer insulation was damaged during installing in the duct, and water has got in, and wicked its way out of the gland...luckily there was a separate earth cable installed.
If your cable was running through another building to the new one, then there's no chance of corrosion to the armour, however as it's ran underground and was installed by builders, who may not have took precautions to prevent damage to the cable.....

 

[andysparkfree]

so to recap so I'm sure

we are saying that the swa won't meet the required csa in copper for bonding
and that obviously not running in the cable that i can not say on its condition which puts even more doubt on the above

 

[Leesparkykent]

I would take an educated quess at the SWA being XLPE and not pvc/pvc...I can't remember the last time I had pvc/pvc swa from a whole salers. Regardless of being XLPE or PVC it's not adequate for bonding if you follow the guidance provided to us.....so it amazes me the NICEIC have given you a blanket statement saying it's adequate.

 

[Ian1981]

Perhaps they ment it was adequate for use as a cpc?

 

[ipf]

Once installed a 50mm 4c, OK for 6 months and then blew.... water through an indentation caused by builders digging machine. water and copper shrapnel blew back through the centre of the cable to the supply fused switch. Wet through and messy. Must have been bubbling a while and probably providing underground heating for the cobbled drive.

 

[Leesparkykent]

The way I see it is the builder sorts his fudge and slaps in a 16mm green and yellow or you make the far end TT. Being a new build you have the opportunity to build a little earth nest if the ground work isn't done...Could you clamp on to some rebar if traditional construction?

 

[westward10]

Perhaps they ment it was adequate for use as a cpc?

Agree which is why I asked what exactly he asked the Brains Trust.

 

[ipf]

The way I see it is the builder sorts his fudge and slaps in a 16mm green and yellow or you make the far end TT. Being a new build you have the opportunity to build a little earth nest if the ground work isn't done...Could you clamp on to some rebar if traditional construction?

Worth thinking about but which is the cheaper. I'd be after a really low Ra, too.

 

[andysparkfree]

no def bonding conductor , but looks like something has been relayed incorrectly , will ring back tomorrow and question them, however if its the case as you guys say ill sum up with the client in which way they want to go earth rod or dig the road up again
im not fussed to much as long as it meets the regs (and all additional material/ labour costs are met

 

[Leesparkykent]

no def bonding conductor , but looks like something has been relayed incorrectly , will ring back tomorrow and question them, however if its the case as you guys say ill sum up with the client in which way they want to go earth rod or dig the road up again
im not fussed to much as long as it meets the regs (and all additional material/ labour costs are met

Personally I don't see why you have to phone back. It's not adequate full stop if it's either pvc or XLPE for bonding if you follow the guidance provided to support bs7671. No to and throwing with the NICEIC tech line will change that fact. You need a solution and that is to install a earthing conductor or if that's not possible due to cost, schedule etc your left with making the House TT. Are you working directly for the client or the builder? Either way I would have a little word with the builder as their fault and solve it together. TT wouldn't be the end of the world if groundwork isn't complete. A couple of earth pits, multiple rods that could be pushed in with a digger bucket if machinery on site, bare conductor linking them and a 16mm green and yellow in to the building. If you went with a couple of 1.2m rods screwed together on two corners of the building and a bare earthing conductor linking them together I bet it would be under £200 in bits and could be put in whilst groundwork was underway..

 

[andysparkfree]

working direct for the builder , and the ground works looked near enough finished apart from the planned new shrubs
i think ill tell them that they have to dig the route up again and get the earth installed, no point blaming the builder , there punishment is undertaking the job twice
and i want to talk to the help desk again to see what they say again ,to if they say something different to before

 

[westward10]

The problem with these helplines and taking their advice is that you need to satisfy yourself through calculation and applying necessary Regulations to prove it is correct. Once you can do this you will never need helplines.

 

[andysparkfree]

yes makes sense

 

[andysparkfree]

so I've just re-rang the NIC and different chap answered , after going through the whole issue again he has said the same again that the 35mm swa steel is more than adequate to be used as a cps and bonding conductor
however i think I'm going to as suggested westward, learn to do the calcs myself
more knowledge is power (or earth in this case)

 

[westward10]

I am most surprised they are giving this opinion. Have they indicated where they have got the 84mm from for the armour and what factor they are applying to it. If you chose to follow their advise you have to satisfy yourself it is correct. I still say their advice is incorrect.

 

[Pete999]

I am most surprised they are giving this opinion. Have they indicated where they have got the 84mm from for the armour and what factor they are applying to it. If you chose to follow their advise you have to satisfy yourself it is correct. I still say their advice is incorrect.

West you should know by now the NICEIC are never wrong

 

[Octopus]

You have to remember that some of the chaps on the helpdesk are not sparks