Earth rod

[uksparks]

3 months ago I sunk in 3 rods, two were 4m deep and the other 3m deep, Ra achieved at the time was 3.1 ohms using a Three lead spike test kit.

i hooked the summerhouse up today and finished it off,

i measured Ra again and it was 2.5 ohms, then just to let you know how close it was to Ze, so accuracy of the spike test, Zdb at the new board came out at 2.88 ohms, that was on the end of a 52m run of 16mm SWA.

im very happy with the end result.

 

[davesparks]

Yes indeed, it's clipped about 12" under against the breeze block edge to the footings, the slot all the way round is filled with stones from Devon I think, it's about 18" deep.

i was going to put a concrete earth rod inspection pit in but he took the slabs too close unfortunately.

So what access have you provided to the rods?

 

[uksparks]

So what access have you provided to the rods?

They are located with the gravel, a quick find with your hands in the marked locations you can find them, it's just it was too close to the edge of the slabs to get proper boxes in, they are perfectly accessible though.

 

[Darkwood]

I give that install less than 2 years before its all compromised and buckled, the issue with running pvc pipe that is exposed to the sun is it expands and quite a bit then contracts at night, because its warm its takes on the bends caused in any buckling that occurs and the colder nights just set the bends hence the permanent buckling - I cannot see any expansion kits in there and because you have conduit into 2 fixed ends this will on exacerbate the issue and even when you do fit expansion couplers the IP rating given hopefully by the sealant used on the joints tends to fail within a few years because of movement anyway... I've ripped loads of similar set-up out before for this exact reason.

Another thing is there could be a large derating factor to be applied to ccc thus affecting front end - that exposed conduit is going to get very warm in the sun and be like a heat trap for the cables inside - been exposed to the sun most of the day I'd be interested to see what a thermocouple reading came up with inside the conduit ..40-50c wouldn't surprise me.

 

[uksparks]

I give that install less than 2 years before its all compromised and buckled, the issue with running pvc pipe that is exposed to the sun is it expands and quite a bit then contracts at night, because its warm its takes on the bends caused in any buckling that occurs and the colder nights just set the bends hence the permanent buckling - I cannot see any expansion kits in there and because you have conduit into 2 fixed ends this will on exacerbate the issue and even when you do fit expansion couplers the IP rating given hopefully by the sealant used on the joints tends to fail within a few years because of movement anyway... I've ripped loads of similar set-up out before for this exact reason.

Another thing is there could be a large derating factor to be applied to ccc thus affecting front end - that exposed conduit is going to get very warm in the sun and be like a heat trap for the cables inside - been exposed to the sun most of the day I'd be interested to see what a thermocouple reading came up with inside the conduit ..40-50c wouldn't surprise me.

I agree, it will get hot, unfortunately there's not much I can do about that and given the options, I hadn't got many really as he wanted it on the outside.

As for the expansion, its got trees all round it, so hopefully within 12 months or so, it will all be in the shade and shouldn't cause much of an issue. Ill be honest, In all the jobs I have done with conduit like this, I have never seen it buckle to any degree that was concerning or make me wish I had done it differently.

I do agree with what you are saying, short of doing it all in steel what else could you do?

 

[Darkwood]

I agree, it will get hot, unfortunately there's not much I can do about that and given the options, I hadn't got many really as he wanted it on the outside.

As for the expansion, its got trees all round it, so hopefully within 12 months or so, it will all be in the shade and shouldn't cause much of an issue. Ill be honest, In all the jobs I have done with conduit like this, I have never seen it buckle to any degree that was concerning or make me wish I had done it differently.



I do agree with what you are saying, short of doing it all in steel what else could you do?

Don't get me wrong I'm not trying to pull your work apart just for the sake of it but instead offer contructive advice, it seems where you have gone wrong here IMHO is you have let the cart lead the horse - so to speak, your customer can tell you what he wants and how he wants until the cows come home but it is up to you to tell him the options and limitations of his preferences.

As for plastic exposed outside - I would be taking a second thought before using it especially where both ends of any run may be to fixed points .

As for alterntives - well a few spring to mind:-

Externally
- cable of choice is a MICC with appropriate colour sheath (A dying or lost art) or a tough shell flex with UV tolerance.
- a stiff but flexible conduit with liquid tight glands.
- Plastic or steel conduit with the appropriate no' of expansion joints but such a set up would probably warrant an agreed inspection routine of say every few years to reseal all joints to keep them IP rated and if steel then ensure you use the IP rated fittings/joints.


I have also resued a few installs and my method seems to work so could be implemented from the start - Use PVC as you have but fit a 200mm piece of suitable flexible UV tolerant plastic flexible conduit in any runs especially the exposed runs ensuring the use of IP rated fittings - these act like and expansion joint but should reduce any movement on the fixed points thus compromising seals is limited.


PS - Look at these or similar and also read this link as it explains in detail the suseptibility of PVC to expansion http://0323c7c.netsolhost.com/docs/Conduit expansion fittings.pdf

 

[shanky887614]

Don't get me wrong I'm not trying to pull your work apart just for the sake of it but instead offer contructive advice, it seems where you have gone wrong here IMHO is you have let the cart lead the horse - so to speak, your customer can tell you what he wants and how he wants until the cows come home but it is up to you to tell him the options and limitations of his preferences.

As for plastic exposed outside - I would be taking a second thought before using it especially where both ends of any run may be to fixed points .

As for alterntives - well a few spring to mind:-

Externally
- cable of choice is a MICC with appropriate colour sheath (A dying or lost art) or a tough shell flex with UV tolerance.
- a stiff but flexible conduit with liquid tight glands.
- Plastic or steel conduit with the appropriate no' of expansion joints but such a set up would probably warrant an agreed inspection routine of say every few years to reseal all joints to keep them IP rated and if steel then ensure you use the IP rated fittings/joints.


I have also resued a few installs and my method seems to work so could be implemented from the start - Use PVC as you have but fit a 200mm piece of suitable flexible UV tolerant plastic flexible conduit in any runs especially the exposed runs ensuring the use of IP rated fittings - these act like and expansion joint but should reduce any movement on the fixed points thus compromising seals is limited.


PS - Look at these or similar and also read this link as it explains in detail the suseptibility of PVC to expansion http://0323c7c.netsolhost.com/docs/Conduit expansion fittings.pdf

i prefer steel myself, did a 100m run a while ago for a network cable now that was a lot of fun. continuous apart from a 1m section and that includes going between two buildings and then through the tugway underneath

 

[uksparks]

FYI i have put that earth wire in a bit of conduit now and it looks much better, only took 5 mins to sort. Ill take a photo later as going for a BBQ.

 

[Guest77]

For those of you who are interested, this is how I ran the cables to the sockets, in 25mm black conduit outside as the customer didn't want to see it inside.

View attachment 29837View attachment 29838View attachment 29839View attachment 29840View attachment 29841View attachment 29842
View attachment 29843View attachment 29844

Did you glue the pipe? if so it will look like a donkey's hind leg by next summer, I am not critising the work mate because the pipe looks neat, but plastic pipe in the sun then a winter will end up all over the shop.

 

[Risteard]

short of doing it all in steel what else could you do?

Use proprietory expansion couplers.

 

[uksparks]

Did you glue the pipe? if so it will look like a donkey's hind leg by next summer, I am not critising the work mate because the pipe looks neat, but plastic pipe in the sun then a winter will end up all over the shop.

Yes I always glue them unless its indoors which I have never had a problem with them, I say I always glue it, on occasion they don't get glued, but generally speaking they get glued.

See amended work below, I agree that the earth looks significantly better in a bit of pipe.

 

[uksparks]

Use proprietory expansion couplers.

I asked in the wholesalers about these, and they said, not only do they not stock them, they have not even sold one of them ever, they said nobody uses them, not only that, have you actually tried to buy one?

 

[Dave OCD]

Despite all the constructive criticism I think that considerable effort has been made to do a really good, neat job. Personally with the number of saddles installed I can't see the conduit distorting or deforming significantly.

 

[uksparks]

Thanks Dave.

 

[R G]

I did a job about 7 years ago in a log cabin / summerhouse constructed the same way as you show , all wiring
was inside the building and was vertical in trunking , I had to go back and reduce the length of the trunking twice because it had buckled and was away from the walls , the timber is settling and shrinking as it ages , I didn't have a problem on the horizontal runs only the vertical . I have a job coming up shortly and customer wants dado trunking for use as an office , my advice don't do any vertical drops if you can help it , if you do use expansion couplers ...

 

[uksparks]

I'm doing a job next week funnily enough, the bloke is an architect and has built this quite large garden office out of 120 wooden pallets, all been borded and skimmed and I'm putting dado trunking in that, it's inly two 3m lengths down adjacent walls though.