Burying armoured cable in garden - what type of sand?

That  is a reasonable point , perhaps I should be clarify - I fully agree the T and E in plastic pipe is not really adequate mechanical protection unless perhaps  cemented into a solid structure.  I'd not be that worried if it was deep in a solid floor in a hanger perhaps, as it will never be dug up until the building is demolished. Crossing a flower bed it is asking for trouble....

The sort of thing I was alluding to is  more organised, and involves armoured cables drawn into ducts that are well below the surface, that are indeed salt glaze pipes from the year dot to the older buildings,  or in a few places their modern plastic equivalent  The fact that it almost never needs to be dug up shows it is a good approach. It is however fully mapped.

From an electrical safety point of view in this thread the armour on the cable is the key thing, it could be direct buried or in sand or whatever, the fact it is in a tube just allows it to be pulled out and changed, rather than by digging up a pathway or something. If you have a choice of cable that means you are actually  relying on plastic  ducting as the sole  protection that is rather weaker. I'd not direct bury twin and earth either....
  I  suggest that on a site where one person is in control, so long  as the cable route is pretty clear from house to shed or whatever the risk of an SWA in the 'wrong' tube is very low - on a complex site with lots of other buried pipes and ducts and other folk rocking up to dig things in a weakly regulated way, then things like the marker tape and the correct colour of plastic duct become far more important.

I'm not advocating disregarding the guidance with gay abandon, more that there are low risk cases where doing something non-standard is still quite a lot better than nothing.

Mike.

That  is a reasonable point , perhaps I should be clarify - I fully agree the T and E in plastic pipe is not really adequate mechanical protection unless perhaps  cemented into a solid structure.  I'd not be that worried if it was deep in a solid floor in a hanger perhaps, as it will never be dug up until the building is demolished. Crossing a flower bed it is asking for trouble....

The sort of thing I was alluding to is  more organised, and involves armoured cables drawn into ducts that are well below the surface, that are indeed salt glaze pipes from the year dot to the older buildings,  or in a few places their modern plastic equivalent  The fact that it almost never needs to be dug up shows it is a good approach. It is however fully mapped.

From an electrical safety point of view in this thread the armour on the cable is the key thing, it could be direct buried or in sand or whatever, the fact it is in a tube just allows it to be pulled out and changed, rather than by digging up a pathway or something. If you have a choice of cable that means you are actually  relying on plastic  ducting as the sole  protection that is rather weaker. I'd not direct bury twin and earth either....
  I  suggest that on a site where one person is in control, so long  as the cable route is pretty clear from house to shed or whatever the risk of an SWA in the 'wrong' tube is very low - on a complex site with lots of other buried pipes and ducts and other folk rocking up to dig things in a weakly regulated way, then things like the marker tape and the correct colour of plastic duct become far more important.

I'm not advocating disregarding the guidance with gay abandon, more that there are low risk cases where doing something non-standard is still quite a lot better than nothing.

Mike.