Is there a reg that specifies CSA of earth wire when earthing the armour on SWA cable? I'm not talking about when using the armour as the CPC, typical situation i'm thinking of is where 3 core SWA is used for L, N & E, and cable is terminated into plastic enclosure both ends, the armour as extraneous metalwork requires earthing.

Julian

Extraneous condutive parts require bonding,the SWA is an exposed conductive part,which requires earthing.Look in the big red book for minimum size earth conductors.

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Regards

Dave(not Cockburn)

Ideally you might take a reading to ensure the conductor can withstand any potential fault current as well...

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Experience can sometimes show that cost prevails over quality and safety, such little self-value that people hold.

Traditionally, the armour is used as a cpc and needs to be terminated at both ends, however, if you use this method you will also need to check that the armour meets the conditions for thermal constraints, ie the adiabatic equation given in 543.1.1

Where a 3 core cable is used on a single phase circuit, the armour is now only used as a protection against damage and should be treated as an exposed conductive part. In this case it only needs to be connected to the MET at one end via a banjo ring (internal installs) or an earthing nut (external installs) (IMO ).

By the way, I was at a trade counter today and somebody mentioned that they had seen 3-core SWA with the colours Brown, Blue and Greeen/Yellow has anybody else seen this colour combination?

Legh

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"Science has overcome time and space. Well, Harvey has overcome not only time and space - but any objections."

543.1.3

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Why do we need Vernier Calipers when we have container ships?

http://www.leghrichardson.co.uk

"Science has overcome time and space. Well, Harvey has overcome not only time and space - but any objections."

Have seen 5 core brown,black,grey,blue& green/yellow.

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Regards

Dave(not Cockburn)

Does it does make more sense for cables sizes up to 25mm2, If SWA cable is going to be used in this manner (B,B,G/Y) rather than as is at present, (B,Bl,G)

Legh

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Why do we need Vernier Calipers when we have container ships?

http://www.leghrichardson.co.uk

"Science has overcome time and space. Well, Harvey has overcome not only time and space - but any objections."

why is the swa a exposed conductive part?. its got insulation around it and a shroud over the gland?

when i run a 3 core swa out to a 3phase motor, i dont want brown, blue, and g/y conductors!!!!

steve

because it fits the definition in BS7671.
because GN8 says it is

It can be touched, gland shrouds are easily removed without a tool, can can also be touched should the cable be damaged e.g. when digging.

EDIT: also I am not sure if the oversheath could be considered insulation, by that I mean is it manufactured to meet the requirements for insulation?

Edited: 05 November 2009 at 07:49 AM by sparkiemike

I'll second that, especially as I was taught that you must not use the g/y for anything other than earth, and you must not oversleeve it!
In fact I read this again somewhere recently, in a document from the ESC/NIC or something like that IIRC.

Most of my time I work without a neutral in the system anyway, with cables of less than 25mm sq normally!

Also remember that the colour codes change when you move from BS7671 to BS EN 60204 which is the equivalent standard for machinery. The only thing that stays without chage is the G/Y and the prohibition of using this for anything other than a protective conductor.

Paul

Paul

514.4.2

On multicore cables the G/Y can be sleeved therefore not restricted to a protective conductor not the best regulation but there

MrP been here one year and two days

OK, it is there but what you suggest is not how I read it!

Paul

544.2

I read this as same size as cpc and no less than 4mm, if no mechanical protection.



Dont forget to use the double lock nut with banjo in between.

or Piranha Earth Locking Nuts, makes things very easy.

Paul

514.4.2

States that G/Y single core cables should be used exclusively as a protective conductor Therefore the implication is that multicore cables containing a G/Y can be sleeved

If you compare the equivalent reg in the 16th pre 2004 amendment
single and multicore cables are included
In the 2004 amendment multicore cables were removed and this carries through to the 17th

The situation would suite a standard 3core flex for use with a class 2 fan incorporating a timer or run on, where the G/Y could be sleeved and used as a switch wire

Mr P

I always thought it good practice to run a earth even when not require for the purpose of testing. Although now Im starting to think maybe theres a reg , or maybe an nic thing. puzzled

I always have trouble getting me pipe grips on those little screws. lol

To answer my own question I was thinking of 411.3.1.1 bottom bit

In the case of a fan fed via a bit of flex, it could be argued that the "point" is the supply end of the flex - so (provided the fan is class II) no need for a terminated earth connection at the fan, nor a CPC in the flex.

- Andy.

In the case of a fan fed via a bit of flex, it could be argued that the "point" is the supply end of the flex - so (provided the fan is class II) no need for a terminated earth connection at the fan, nor a CPC in the flex

Not a very good argument.Would you class the point as being the accessory? I'd say the accessory is the fan enclosure.

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Regards

Dave(not Cockburn)