External Cable Depth Best Practice/Regs

[pforeman]

Hi All,

Can someone please advise what best practice/regs are required for supplying an external building/shed. (i.e. from back of house 60ft of garden to shed)

Is it just an armoured cable burred in the ground 1.5ft or so or as coax & CAT5 is also required is a duct/pipe or similar a better option? (And if a duct used are the cable requirements different?)

Thanks for the help.

Cheers
Pete

 

[plugwash]

IIRC Regs require that underground cables should be burried deep enough to protect them from reasonablly forseeable uses of the ground they run under. There are guideline depths (IIRC it's 450mm for gardens, something more like a meter for roads) but they are just guidelines.

You shouldn't put mains and data in the same duct. I would fit a duct for the communications wires as communications requirements are likely to change over time. I generally wouldn't bother with a duct for mains wiring. SWA is fine burried directly.

The cable should be bedded in sifted material (free of stones). Using sand instead of soil may make sense to give a visual indication that something is happening if someone misses the warning tape.

You should place warning tape about a spades depth above the cable.

 

[mfarrow]

The IET's GN1 advises 0.5m, with 450mm being lifted from NJUG recommendations into the table below.
View media item 67014

 

[PrenticeBoyofDerry]

Best practice would be to dig a trench no less than 450mm, install a duct to to route the cable and an additional draw string, in case it ever needs replacing.
Electric cables and data cables are best routed separately.
Also make a route plan/diagram of where the cable is laid for future reference.
Obviously cable calculation for the load and voltage drop should be made prior to the purchasing of cable.

 

[pforeman]

Thanks for the info. I'll start digging!

Cheers
Pete