SWA for 3 Phase Installation

[SparkyDave]

have been happy in the past to use 4 core although i find that 5 core often looks nicer and is generally a neater install.


although sometimes dependent on what you are doing the cost outways the pro's

 

[jamie-spark]

Any Hoo if incorporating a cpc within the swa there is still a reqirment to ensure the armouring is connected to earth

 

[scotsparky]

True Jamie nice to see the scots have it covered.
Th table in GN1 is exellent but be carefull about the type of cable used as there is a difference in K factors

 

[gaulty]

I was under the impression that over a certain size of swa you cant use the armour as an earth and a seperate earth needs to be run in, unless there's a core for ie 5 core. personally never used 5 core and usually run in a seperate earth if needed. but always make sure that swa armour is earthed.

 

[termite]

Thanks gaulty. Since the inception of 17th Edn. I have always run a suitable seperate CPC alongside TP&N 4-core SWA buried cables and also for 3-core TP cables. Most of my work is on rural services for private pumped water supply installations, so longer power supply cables are the norm in our business as water engineers. I think that your take on this shows a responsible attitude to earth bonding.

Regards, termite.

 

[Knobhead]

It's a pitty SWA cables are so crap now. Under M&Q and foundry regs no CPC is required. The cables had 1 tinned copper to 3 steel wires in the armouring. Better still install PILCDWA the return path was often better the conductors

Thank god I've retired

 

[NoSparks]

OK. GN1 specifies that for 35mm SWA the armour is an acceptable CPC. But here comes the runt.
Irrespective of the Regs, (or is it in very strict adherence of the regs?) the MET must be at the supply head and the main bonding must run to the MET. It is unacceptable, and they will NOT provide a connection, if the bonding is to a Dis Board fed from a sub main.

Also, tails of more than 3 meters are Unacceptable. If the tails would be more than 3 meters then you have to install a single way DB (switch fuse or other) within 3 meters and take the sub main from that. More over, and contarary to the EDF web site which only requires an isolator, but only in some areas, it must contain fuses (or I suppose some other form of cutout) . The Reason... "so that they do not have to change their fuses if there is a fault with the sub main". ... Sounds rediculous to me because there is no discrimination, however that is their requirement before thay will connect a meter.

 

[mogga]

http://www.earthingnuts.co.uk/pdf/pvc_xlpe.pdf swa earth sizes for armours

 

[Andy Greaves]

I was under the impression that the tables in GN1, that refer to sizes of armourings in SWA, were an indication to whether the armourings comply with table 54.1 (54G in 16th). If the armourings do not comply then the adiabatic equation needs to be done in order to ascertain whether the armouring are capable of taking the current produced under earth fault conditions.