Burying a mains cable in the garden

Haven't had a good look at it in a while now, will have to refresh my memory, but it's definitely 3 core. It'll date from the early 90s, yet I seem to remember it's red, black, and green/yellow... that seems like a mixture of the old and new colour codes to me, but what do I know.
The UK did not fully adopt harmonized colors in one go.

The first thing to switch were flexible cords, presumably driven by the desire to harmonize standards for electrical equipment. This was before my time, but a thread over on the IET forum suggests the harmonized colours in flexes were allowed from 1963 and required from 1971.

Then came green/yellow earths in fixed wiring. Again this was before my time, but the thread on the IET forum suggests that green/yellow earths in fixed wiring were allowed from 1970 and required from 1977.

That is how things remained for a long time. My understanding is that the IEE (now the IET) were reluctant to adopt the harmonized phase and neutral conductors because of issues relating to three phase. Firstly the possibility for confusion where old and new colors met and secondly the issue that at the time the harmonized colors did not distinguish between L2 and L3 introducing the possibility for phase rotation errors.

Then in 2004 (with an allowance to use up existing cables until 2006), the UK finally brought in full harmonized colours for fixed wiring. As part of this the harmonized colors themselves were changed, introducing grey for L3 (in older harmonized cables both L2 and L3 were black).

Further complicating matters is that 3 core SWA is most commonly produced in 3 phase color codes, but it is also possible to buy it in single phase+neutral+earth colors. I think this was the case even pre 2004 but my memory may be failing me.

So 3 core SWA exists with at least three and possiblly four different color codes.

Red,Blue,Yellow: old 3 phase colors
Red,Black,Green/Yellow: pre 2004 single phase colors (not 100% sure on this one, I think it existed but my memory may be failing me and I can't find any photos right now)
Brown,Black,Green: harmonized single phase colors
Brown,Blue,Green/yellow: harmonized single phase colors

When cable coded with three phase colors is used for single phase plus neutral and earth, the cores used for neutral and earth should be reidentified with tape or sleeving, but in reality this does not always happen.

With the pre-2004 cables the norm, when using a 3 core SWA with three phase colors for single phase was to use the blue conductor for neutral and the yellow conductor for earth. With the post 2004 cables, the electrical industry associations pushed grey neutral and black earth, but many DIYers are likely to have used black neutral and grey earth. Great care should be taken that conductors are correctly identified.
 
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Europe is far from harmonised.
Brown, Black, Black & Brown, Black, White are still very common. 2016 I worked in a new build plant room, the electrical contractors were a spanish company and both of those combination SWA's were installed, along with harmonised.

Purple is still being used by some in france for switched live even in SWA.
 
Thanks for the fascinating insight into colour schemes! But even then, I have to be different – having had a good look again, mine are red, grey, and green/yellow. Oh well, the red is definitely live, and I can guess what the g/y one is, so…

But as always with EVERY DIY job I bring to these hallowed pages, it gets worse and worse… just when I’d familiarised myself with all the procedures and bits and pieces, I discover that the external diameter of my armoured cable is… hard to measure exactly, but I’d say 6 or 7mm FFS – the thinnest SF do is 11.7.

Well, maybe you can join different thicknesses together… I suppose no reason why not?

I can’t remember how 1.5/2.5mm etc relate to current capacity – somebody enlighten me please?

I’m only planning to power a small pond pump here, less than 100W, so I’m assuming the thinnest would do…?
 
Thanks for the fascinating insight into colour schemes! But even then, I have to be different – having had a good look again, mine are red, grey, and green/yellow. Oh well, the red is definitely live, and I can guess what the g/y one is, so…

But as always with EVERY DIY job I bring to these hallowed pages, it gets worse and worse… just when I’d familiarised myself with all the procedures and bits and pieces, I discover that the external diameter of my armoured cable is… hard to measure exactly, but I’d say 6 or 7mm FFS – the thinnest SF do is 11.7.

Well, maybe you can join different thicknesses together… I suppose no reason why not?

I can’t remember how 1.5/2.5mm etc relate to current capacity – somebody enlighten me please?

I’m only planning to power a small pond pump here, less than 100W, so I’m assuming the thinnest would do…?

Are you sure its SWA? The smallest SWA available is 12mm diameter on my chart, for 2 core 1.5mm.

1.5mm buried direct is 25A current carrying capacity, according to the book.
 
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Are you sure its SWA? The smallest SWA available is 12mm diameter on my chart, for 2 core 1.5mm.

Well well... after all that, I think you're right - it isn't. It looks like it, it feels like it (very stiff, hard to cut plastic outer)... but I don't think it has the steel armour.

That leaves me with a quandary, doesn't it. It will have been there since the house was built (1994 I think - I've only been here 3 years), and goes from where you see it, under some flags, about 25' to the house, so I guess in practice it was fairly safe.

Originally it came up through a concrete block to a pedestal kind of light, but the light had all rotted away, so I decided to break the concrete up and expose the cable so that I could do something else (undecided at that point) with the power...

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PS just stuck the little socket on the end today as I needed to do some drilling
 
Is that NYY cable, not the same as SWA but can, I believe, be buried if certain conditions are met.

A badger could definitely chew through that.

Blup
 
Is that NYY cable, not the same as SWA but can, I believe, be buried if certain conditions are met.

A badger could definitely chew through that.

Blup




I think a badger could do enough damage to an SWA cable to ruin it.

I don't think it would get through much of the armour, but damaging the outer sheath would surely allow water to find it's way in, corrode the armour, and eventually allow water to travel through the cable.

Still kind of ruins the cable, particularly if unnoticed for years.
 
I think a badger could do enough damage to an SWA cable to ruin it.

I don't think it would get through much of the armour, but damaging the outer sheath would surely allow water to find it's way in, corrode the armour, and eventually allow water to travel through the cable.

Still kind of ruins the cable, particularly if unnoticed for years.
Even little cute little furry moles will have a good go at SWA
 
Oh you don't know what you're missing, I parcel some up and send them over for you(y)

Heh - I lived in Gloucestershire for many years, and saw them do their engineering works everywhere. My cat even brought one through the catflap - F* knows how he caught it...
 
Heh - yeah, I just meant because moles are mostly under the ground. But I guess maybe they come up sometimes...
The comment might also have been related to the fact that, as far as I am aware, moles (who, as you say, usually live underground) apparently have very poor eyesight!

Kind Regards, John
 
Sorry... if anybody's still reading this, is there any kind of (resin?) joint, preferably on SF, which will join a length of SWA to the existing NYY cable at one end, and the cable from the pond pump at the other end?

Haven't bought the pump yet, but a previous one I owned had something like standard mains flex feeding it...

Oh, and just to make things more interesting, these joints will be underground (though safe under concrete slabs) :D
 

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