Post by thread:[EE] Mains outside

I need to have mains (230V) outside the house, at a remote part of the garden, and would like to know if this solution is (a) safe (b) feasible (c) legal [intimate knowledge of NZ law assumed !!] I have plenty of 2-core mains-rated cable - obviously no earth. At the remote end the circuitry will be in a metal box. If I use an RCD http://en.wikipedia.org/wiki/Residual-current_device (which I do when working with tools outside), bang a metal stake into the ground, to which the metal termination box is connected, and put a fuse on Active, is this going to pass muster wrt not killing people (especially me) ? TIA

> I need to have mains (230V) outside the house, at a remote part > of the garden, and would like to know if this solution is (a) safe > (b) feasible (c) legal [intimate knowledge of NZ law assumed !!] > > I have plenty of 2-core mains-rated cable - obviously no earth. At > the remote end the circuitry will be in a metal box. If I use an RCD > > en.wikipedia.org/wiki/Residual-current_device > > (which I do when working with tools outside), bang a metal stake > into the ground, to which the metal termination box is connected, and > put a fuse on Active, is this going to pass muster wrt not killing > people (especially me) ? i don't know anything about NZ regs but i do have some familiarity with the british ones and your idea screams dodgy as hell to me. firstly you say nothing at all about core sizes, this matters from 3 points of view: volt drop, disconnect times (with whatever protective device you use) and cable rating. secondly the cable doesn't sound like its armoured in any way which is going to be a problem if you bury it thirdly the cables outer sheath is unlikely to be suitable for long term outdoor use especially if the cable is white (black pigments tend to block UV penatration, thats why most proper outdoor cables are black). finally earth rods (if considered an acceptable as a means of earthing where you are) are not a DIY job to install. Its all too easy to end up driving d into ground that is not very conductive.

What you suggest seems to be safeishif done properly - but I would be surprised if it were legal. 1. The cable needs to be rated for direct burial. (XLPE sheath & neutral screened or armoured). You may be ale to pull the cable through conduit however. Depth needs to be > 600mm IIRC. with a marker tape & protection above (eg ground treated timber) if not armoured. 2. 2 core cable would be unlikely to be accepted , even with a RCD and a remote earth. (You could end up using single insulated appliance on the circuit) 3. There are restrictions on where you can provide earth rods depending on the protection level of the circuit. If the endpoint meets the requirements of a switchboard, then there are circumstances where you can earth the neutral (in a MEN system as in NZ) but there's a special condition involved that I can't remember. 4. Where earth rods are employed, the effective "earth resistance" must be measured and must be less than a specified value. 5. Installation (or at least proper inspection) by a registered sparky &/or inspector would be required. The above is from memory & could be off track but I think is OK. - Are the wiring regs not available online? RP On 19/01/07, Jinx <spam_OUTjoecolquittTakeThisOuTclear.net.nz> wrote: {Quote hidden}> I need to have mains (230V) outside the house, at a remote part > of the garden, and would like to know if this solution is (a) safe > (b) feasible (c) legal [intimate knowledge of NZ law assumed !!] > > I have plenty of 2-core mains-rated cable - obviously no earth. At > the remote end the circuitry will be in a metal box. If I use an RCD > > http://en.wikipedia.org/wiki/Residual-current_device > > (which I do when working with tools outside), bang a metal stake > into the ground, to which the metal termination box is connected, and > put a fuse on Active, is this going to pass muster wrt not killing > people (especially me) ? > > TIA > > -

I would suggest using underground plastic conduit, it's cheap compared to the cable, provides considerable protection. Go one size larger than the recommend size if possible, makes pulling cable easier. Depth should (must) be below your frost line (check your local authorities for this)( here in Northern Ohio 3.5' (1M) is required, though I have on construction sites encountered as deep as 7' (2M). Don't recommend aluminum cable, stick with copper if long term reliablity is important. I replaced our 200 amp underground service alum. with copper last summer, sure glad it was in 3" plastic conduit. For grounding check with your local authorities, or people in the trade. Generally the supply houses that deal with contractors and industry know what's necessary. peter green wrote: {Quote hidden}>> I need to have mains (230V) outside the house, at a remote part >> of the garden, and would like to know if this solution is (a) safe >> (b) feasible (c) legal [intimate knowledge of NZ law assumed !!] >> >> I have plenty of 2-core mains-rated cable - obviously no earth. At >> the remote end the circuitry will be in a metal box. If I use an RCD >> >> en.wikipedia.org/wiki/Residual-current_device >> >> (which I do when working with tools outside), bang a metal stake >> into the ground, to which the metal termination box is connected, and >> put a fuse on Active, is this going to pass muster wrt not killing >> people (especially me) ? >> > i don't know anything about NZ regs but i do have some familiarity with the british ones and your idea screams dodgy as hell to me. > > firstly you say nothing at all about core sizes, this matters from 3 points of view: volt drop, disconnect times (with whatever protective device you use) and cable rating. > > secondly the cable doesn't sound like its armoured in any way which is going to be a problem if you bury it > > thirdly the cables outer sheath is unlikely to be suitable for long term outdoor use especially if the cable is white (black pigments tend to block UV penatration, thats why most proper outdoor cables are black). > > finally earth rods (if considered an acceptable as a means of earthing where you are) are not a DIY job to install. Its all too easy to end up driving d into ground that is not very conductive. > > >

Peter, > i don't know anything about NZ regs but i do have some familiarity > with the british ones and your idea screams dodgy as hell to me "dodgy" is a word I can appreciate, and I understand your concerns. But despite my flippant tone, I would like to do this properly for a variety of reasons > firstly you say nothing at all about core sizes, this matters from 3 > points of view: volt drop, disconnect times (with whatever protective > device you use) and cable rating. > secondly the cable doesn't sound like its armoured in any way > which is going to be a problem if you bury it I had a second look at some other cable I have. I thought it was just heavy-duty data cable, but I see it's way better than that. 25m of monstrous Olflex Classic 100 CY 4G40 that my brother rescued undamaged for me from a demolition http://www.lappusa.com/PDF/Pg45-46-Olflex100-100CY.pdf as well as some lengths of Olflex 2-core + braid, more than I need, and the application is only 100W max Outstanding ! God bless scavengers ! > thirdly the cables outer sheath is unlikely to be suitable for long term > outdoor use especially if the cable is white (black pigments tend to > block UV penatration, thats why most proper outdoor cables are black) The cable I was thinking of using, before looking up the Olflex, is in two types - black fig8 and red fig8, both 1.something mm solid core. Don't need that anymore it seems > finally earth rods (if considered an acceptable as a means of earthing > where you are) are not a DIY job to install. Its all too easy to end up > driving d into ground that is not very conductive. I shall now be able to supply a cable Earth to the remote point. As suggested, it was going into conduit as well

higher voltages are run all the time underground....how does it get from a transformer to you meter? Sometimes overhead...sometimes underground. I've run (GFI protected of course) several 115VAC distributions to the front and back yard, all in conduit. You can use direct burial cable but still risk having it cut into, conduit is just more difficult to accidently put a shovel thru it. Having the distribution off a GFI (in 5 yrs never had it trip) gives the secondary protection if there ever is a problem. I even have remote controlled relays functioning as well to turn on and off the waterfall. --------------------------------- Have a burning question? Go to Yahoo! Answers and get answers from real people who know.

Roy wrote: > You could always use mains voltage feed from a 30ma RCD (residual current > device), also would depend on local electrical rules - in NZ & Australia > 30ma RCD's are the norm. In Italy too. A coworker of mine said that, here in Italy, you should have metal pipes carrying the wire, or plastic one ("merlet"), both possibly sunken into concrete. Wire should have Ground, of course. Beyond to this, no isolation transformer is needed usually. RCD is ok. As for the 48V solution, it may be good.. if you don't have big loads, nor the need for 220V. Otherwise, you're mostly making it unnecessarily complicated... -- Ciao, Dario

Jinx, On Tue, 23 Jan 2007 10:41:07 +1300, Jinx wrote: {Quote hidden}> > > > You could always use mains voltage feed from a 30ma RCD (residual > > current device), also would depend on local electrical rules - in NZ & > > Australia 30ma RCD's are the norm > > That's kind of my thinking. I use an RCD with extension lead outside > a lot. I see what I'm wanting to do now as an extension lead that > happens to stay out all the time. If I'm super super careful and make > it safe and secure, I don't see a problem The thing to remember is that a loose extension lead is visible and obvious, so you wouldn't expect damage to it to happen unnoticed. But a fixed cable has to be protected such that it isn't damaged by operations you can predict will happen - for example if it's buried you have to make sure it's deep enough, well-enough protected, and marked, such that digging won't damage it. In the UK you basically have to use SWA (Steel Wire Armoured) cable outside,

Peter, On Tue, 23 Jan 2007 23:10:21 -0000, peter green wrote: > > Which aisle of B&Q are they in? :-) > they aren't but neither are sizes of SWA that give you decent volt drop figures for even a small supply down a large garden. Well I wasn't being that serious! :-) Although 2.5mm^2 is OK of you're just running a shed with a light and one power tool a few metres from the house. Any use of SWA must be better than the lashup that was in place when I bought the house - ordinary 2.5mm^2 T&E strung along the garden wall to the garage about 50m from the house. It plugged in in the kitchen, and one day I plugged it in via an RDC adaptor, which tripped instantly. I measured what was happening - about 1.8A was "leaking" somewhere! At that point I cut and uninstalled the cable... > > I think Jinx would balk at spending several times more on tools > > than on the materials to do the job - all of the above rather > > demand that, sadly. > that applies to MICC and steel conduit but not to split-con. split-con is unfortunately a little tricky to get though. I have to say I've never seen split-concentric cable in the flesh, and I have no idea how you terminate it. Are there special terminal boxes, or glands, or what? Cheers, Howard Winter St.Albans, England