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Discuss Terminating SWA Cable. in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net

U

UK_Night_Owl

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I wounder if anyone would be so kind as to offer some advice. It's not something I'm actually wiring up, it's just a little theory project to do with college.

If I want to come from a breaker switch in a distribution board, and run a supply along a cable tray in SWA cable to a 32amp three phase and earth interlocked socket. From looking in tables I have figured I'm going to need to use 4.0mm SWA cable and obviously I'm going to have to terminate the cable at each end using glands. What I'm not sure about is how many core cable should I use, as should I use the outer steel wires of the cable as the CPC Earth), which would mean I could use 4 core cable, or should I use 5 core cable, and one of the cores of the cable as the CPC as well as connecting the outer steel wire sheath to earth?

The other thing I'm not too sure about, if I can use the outer of the cable as CPC, when I terminate it to the interlocked socket, this has a plastic housing. Would I therefore use one of those washers around the gland with a the little bit that sticks out and make a connection to this and then take this in to the earth terminal?

Thanks for any advice offered

David
 
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S

sparkyork

id personally go for a 5 core, although its all about personal preference and also the calculaion to make sure the armouring is sufficient for acting as cpc. thats why id stick to a designated earth core.

you should always use the "banjo" on the swa gland and connect from this to the cpc of the circuit at both ends of the cable.
 
B

Bane

  • Thread Starter Thread Starter
  • #3
Run a seperate Earth

Of course, you'd only run a seperate earth if it was a distribution circuit.
Not a final circuit ;)

...Thing is though you don't always run a seperate earth with a distribution circuit either, you would if it was a 2 core swa mind.

Hope this has helped some?

Night all!
 
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U

UK_Night_Owl

  • Thread Starter Thread Starter
  • #5
Thanks for your help on this one guys.

I got it figured now. Use on of the conductors in the cable as the CPC / earth, and at each end of the cable where I'd terminate it in a gland, make sure I've got the banjo washer on here, then make connections to the CPC / earth. So, instead of using the steel wire part of the cable as the CPC / earth, what I am in effect doing is bonding it the the CPC / earth.

I don't know if it's me being a bit dim here, coz it wouldn't be the first time, but I'm a little confused by what Bane said:

Of course, you'd only run a seperate earth if it was a distribution circuit.
Not a final circuit


...Thing is though you don't always run a seperate earth with a distribution circuit either, you would if it was a 2 core swa mind.

Any chance of a for example on that one mate??? - I'm only a first year apprentice at this electrickary lark!

David
 
S

sparkyork

if you were installing a 2 core SWA to whatever (consumer unit or whatever) then you would probably run a seperate earth along with it, rather than relying on the armouring as the earth. obviously if you run a 3 core with a earth as one of the cores you wouldn run a seperate earth.

alot of this is personal preference and some folk will use the armouring as the earth. there is nothing wrong with it so long as the necessay calcultions are made to establish it is satisfactory.

imho its better to run a seperate earth but thats just my opinion

rich
 
Comment removed. He's an apprentice, year 1 of course he doesn't know Trev.
Now stop grumping you miserable old git:)
 
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S

Specialist

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  • #8
Blimey: That's a bit old to ressurect is'nt it trev lol.
 
There must be something going on with my browser. It keeps dragging up old things. The other day it was Gary Mason dying which was a year ago nearly, now this.
 
4

41steve

  • Thread Starter Thread Starter
  • #10
the outer steel wire can be used as the CPC using the banjo's and fly leads to provide termination at the earthing terminal. it would normaly only need to be earthed at one end of the cable but both in this case. there is a table available which proves the outer sheath can be used as the CPC. in any case the sheath and any unused conductor in a multi core cable needs to be earthed.

as its a project ensure that ALL the main bonding is in place before any works are carried out.
 
4

41steve

  • Thread Starter Thread Starter
  • #12
theres a table in one of the publications that proves u can.
 
4

41steve

  • Thread Starter Thread Starter
  • #13
sure there are young lads on ea that have the same questions 2 ask :)))
 
S

Specialist

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  • #14
There must be something going on with my browser. It keeps dragging up old things. The other day it was Gary Mason dying which was a year ago nearly, now this.
Thought it was just me things like that happened to lol. Another 1 I keep getting is when i'm in the middle of reading a topic I get a warning that leaving the topic will delete any stuff in the editor, or words to that effect. Drives me B****y crazy. (Go on say it, i'm already there:rolleyes2:).
 
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G

Guest123

  • Thread Starter Thread Starter
  • #15
Thought it was just me things like that happened to lol. Another 1 I keep getting is when i'm in the middle of reading a topic I get a warning that leaving the topic will delete any stuff in the editor, or words to that effect. Drives me B****y crazy. (Go on say it, i'm already there:rolleyes2:).

You must be using google chrome then.:sailor:
 

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