R1+R2 - two way lighting - 2.7 ohms, can i get your opinions please?

trev · Dec 30, 2014

TJ Anderson said:
What does not comply with what he has done? Nothing wrong with TT. if he wants to. The only issue it seems is a high R1 +R2 on garage lighting circuit.

There is nothing wrong with making a decent TT mate, I do it often. What's worrying me is that the OP seems to have been talked into doing something which he seems unsure of by someone who hasn't got a clue.
What is wrong with extending a perfectly sevicable TN-C-S when it is available.

Geordie Spark · Dec 30, 2014

telectrix said:
failing which, plumbing might be an alternative career path.

Careful now ya Scouse git!!!

Next time ye'll be sortin yer UFH problem and gettin' yer new camera yersel !!!!

D Skelton · Dec 30, 2014

srl-8 said:
Leesparkkent - export earth (meaning, use the swa as a means of earthing. ) I have not used this and TT garage instead.

May I ask what on earth you were thinking and why?

davesparks · Dec 31, 2014

This cut-off copper pipe which was previously being used as the earth for the garage, what Ra did it give you? I assume you did actually test it before you decided it was not ok to keep as an earth.

The earth electrodes you have installed, what size are they? How long are they? How many positions and how far apart are they?

Why are you unsure as to whether the SWA has been earthed at the supply end? This must be done regardless of what you have done at the load end.

Are there any extraneous parts in the garage which need main bonding? (I suspect the previously mentioned copper pipe is, unless you have go grid of it completely)

Engineer54 · Dec 31, 2014

uksparks said:
The CSA of the armouring, I've got a table somewhere showing the CSA of each size SWA, I think a 2 core SWA has armouring equating to 16mm2

16mm2 of what, Steel?? You require the equivalent of 10mm2 of copper to comply with bonding requirements for a typical domestic PME supply, and 16mm of steel doesn't come close. Copper has 8 X the conductance of steel!!

Engineer54 · Dec 31, 2014

I think the OP is going to have a hard time explaining this buckshee garage installation to any assessor!! Not that it'll matter too much, as i have no doubt he'll still get his badge of competence!!

Deleted member 26818 · Dec 31, 2014

Engineer54 said:
16mm2 of what, Steel?? You require the equivalent of 10mm2 of copper to comply with bonding requirements for a typical domestic PME supply, and 16mm of steel doesn't come close. Copper has 8 X the conductance of steel!!

Did he not qualify the statement by asking if there were any extraneous-conductive parts?

Engineer54 · Dec 31, 2014

spinlondon said:
Did he not qualify the statement by asking if there were any extraneous-conductive parts?

Not to my knowledge, but i'm not going back over 4 pages of posts to check... !!

Deleted member 26818 · Dec 31, 2014

I thought that he had, otherwise I would have said something.

D Skelton · Dec 31, 2014

Engineer54 said:
I think the OP is going to have a hard time explaining this buckshee garage installation to any assessor!! Not that it'll matter too much, as i have no doubt he'll still get his badge of competence!!

Now now, I'm sure the OP is highly competent and you're just being mean. We've no time for those sort of comments on here as they imply that he in fact isn't, and what's more, comments that question the competence of other people automatically become impolite no matter how they are asked! So you go away you nasty man. Hang your head in shame!

I'm sure the totally unbiased assessor will find no fault whatsoever with this installation. In fact, I would go as far to say that the OP's willingness to shun that terribly unreliable PME connection with a horribly low Ze value in favour of what is inevitably a highly stable and widely accepted as best practice TT connection with a brilliantly high Ze value, utilising nothing but the best 3/8" rod will be applauded by him/her.

Deleted member 26818 · Dec 31, 2014

You never can be too sure.

HappyHippyDad · Jan 19, 2015

How did the assessment go srl-8? It's always nice to get some feedback..

If this was your first assessment with stroma then I'd be very impressed/suprised if they passed you first time as they are quite thorough. I'd also be interested in what they said about using a rod, rather than extending the EPZ and also what they thought of the high R1+R2, just interested.. not having a go at you..