SWA into ground

[chowbasa]

Do I have to install ducting, how deep do I dig, I have read somewhere that half a metre is adequate if marker tape is used, and to top it off what reference method do I use to calculate current carrying capacity.

 

[breezer]

load requirements determine cable size. (as does volt drop)

load?

distance of cable run?

 

[chowbasa]

60A per phase x 3 x 60 metres

 

[BR]

your going to need 16mmsq. Volt drop for 60M is (off the top of my head) around 3.5V, which is acceptable. Bear in mind that 16sq in SWA is quite expensive.

 

[chowbasa]

But can I just chuck it in the ground does it count as installation method 1

 

[BR]

yes SWA can simply be burried straight. The exact regs for britain i cant help you with. 0.5m sounds fine.

 

[Big_Spark]

yes SWA can simply be burried straight. The exact regs for britain i cant help you with. 0.5m sounds fine.

EXCUSE ME..you do not simply "chuck cable in the ground", all cable that is burried should be a MINIMUM of 450mm below the surface, should be INSIDE ducting and should also be bedded in sand or builders gravel. This should be CLEARLY indicated by marker tape stating

CAUTION. BURIED CABLE

Anything less is a cowboy job.

 

[chowbasa]

What about installation Method 1

 

[Big_Spark]

What about installation Method 1

By that I assume you mean clipped direct to a wall or fence.

Well you can do this, my personal feelings are that you should not in a domestic situation as there are a number of things to consider.

Firstly, the wall or fence should be structurally sound and a permanent structure, larch-lap fences and similar don't really fit this description.

Second, you must own the structure in question or the actual owner can or may ask you to remove it..you've seen neighbours from hell I presume

Third. The cable is susceptible to damage from outside influences beyond your control which could degrade the integrity of the cable.

Realistically this is a judgement call you need to make for each particular job and the circumstances there.

 

[BR]

all cable that is burried should be a MINIMUM of 450mm below the surface, should be INSIDE ducting and should also be bedded in sand or builders gravel. This should be CLEARLY indicated by marker tape stating

CAUTION. BURIED CABLE

Anything less is a cowboy job.

FWL just out of interest, is this actually done, ducting etc. In domestic installations in ireland SWA must be burried 650mm and marker tape used. As far as i know in britain (open to correction here) the procedure you describe can be used with standard PVC T&E. A practice which is not allowed here. So what is the advantage of using SWA if ducting is required.

 

[Big_Spark]

T&E should not be used in ducting in the UK, it is not temperature rated for external use, SWA is.

SWA should always be used in ducting to prevent damage of the outer sheath caused by Earth movements, animals in the ground..moles etc which can allow moisture inside the outer sheath of the SWA thus degrading the ability of the Armour to do its job, especially if the Armour is providing the CPC.

Further, ducting also prevent accidental damage caused by persons digging in the ground, they hit the marker tape and duct first, not the cable. If you only have the marker take above the cable, it is still possible to damage the cable before you realise that a cable is there.

 

[sterose]

yes SWA can simply be burried straight. The exact regs for britain i cant help you with. 0.5m sounds fine.

EXCUSE ME..you do not simply "chuck cable in the ground", all cable that is burried should be a MINIMUM of 450mm below the surface, should be INSIDE ducting and should also be bedded in sand or builders gravel. This should be CLEARLY indicated by marker tape stating

CAUTION. BURIED CABLE

Anything less is a cowboy job.

Forget the ducting, just make sure you bury it plenty deep.

 

[Big_Spark]

Forget the ducting, just make sure you bury it plenty deep.

That is a stupid thing to say as you are encouraging people to break the law..visve Electricity Supply Regulations Act 1989 which states, and this is a cut and paste post.

Only cable meeting the requirements of BS5490:1977(1985), BS5593:1978(1991), BS6207, BS6346:1997, BS6724 : 1997, BS7889 : 1997, shall be used for external purposes where such cable is to be buried in the ground. All such cables must be enclosed in cable ducting manufactured to comply with BS EN 50085 and BS EN 50085-1 : 1999. Such ducting must be laid upon a bed of sand or similar material which must have a depth of not less than 100mm. The Ducting must be covered with a layer of sand or similar material having a depth of not less than 100mm, this sand or similar material must be identified in accordance with BS1710 : 1984(1991) using indication tape manufactured in accordance with BS 5378-1:1980 which must be a minimum of 450mm below surface

As you can see, the law is quite strict on this point.

 

[chowbasa]

Reference method. What method does a swa buried into ducting come under. Looking in the blue book page 213 at the top I make it ref method 4 but then try and find current carrying cap for ref method I cant or am I missing something.

 

[chowbasa]

Found some more on this ducting
page 94 blue book reg no 522-06-03
Some say yes some say no.