My little shed project is coming on OK, I currently have ground workers in to do small foundation and trench to run cable/water/internet from house to shed.
They are backfilling the trench with 20mm to dust right now and i just noticed two small loops in the 25mm dia armoured power cable where it has not been unravelled correctly – 4-6″ diameter, its at 750mm below ground – should I be worried or let them carry on? I know its not great practise, but once its buried it’ll be fine right?

That’s a pretty tight bend for armoured cable but I doubt its damaged anything. Who’s wiring it up? Have they inspected the cable before it gets hidden?. As is its probably fine but a slap dash job and I wouldn’t be happy to pay for it being done badly. Better to put a couple of runs of conduit in then power cable, data, etc can all be pulled through later.

Its OK, I’ve just been out and we have unravelled properly..
FYI The armoured cable is 300mm away from 80mm conduit which has data and pull rope in it.
The armour gives pretty good shielding to prevent issues with the data but better to separate as much as poss to prevent interference.

Should be initially be backfilled with sand then aggregate.

you don’t want loops in your armoured, it creates a stress point in the cable so when fill is applied, depending on how brutal its packed or the weight, or sharp pointy stones, have a greater chance to damage the cable. Dust is as good as sand. 600mm with an armoured is deep enough.