Armouring for earth

tigerpaul · Mar 21, 2012

Hello Fellas,

I think I might have dropped a ------- (never a good feeling)
All my SWA cables turned up for a job I'm about to start.
I've got 10mm 2 cores and 4 cores, for SP&N and TP&N DB's
Also 16mm 2 cores and 4 cores, for SP&N and TP%N DB's

Now I'm thinking about whether the armouring will suffice for the earth. I have no information on the design of the job so I'm unaware of any Ze or pfc values.

I know I can always strap a G&Y cpc to the cable later but it looks untidy and I'll have to go back to the gaffer saying I miscalculated on cable (and look like a muppet)

I know I should have got 3 and 5 cores in the first place!

tigerpaul · Mar 21, 2012

Okay I've just found the "sticky" on this subject, and am reading hoping for the best.

Would still appreciate anyones comments though...

Welchyboy · Mar 21, 2012

there is a guide on here i have seen before about values of SWA sheath as a cpc that i stuck in my regs book, and im pretty sure as long as your using PVC/SWA/PVC and not XLPE cable your fine until you start getting into the big boy sizes of around 95mm+

micknew · Mar 21, 2012

Agree with Welchyboy.
We always calculate swa sizes with Amtech software and have never had a failure flagged up for the armour as cpc. We specialise in industrial works in foundry's etc so have done hundreds of calcs for swa's.

Richard Burns · Mar 21, 2012

These are the values I have for the armour copper equivalent csa for
10mm2
2 core PVC 17.7mm2
4 core PVC 20.3mm2
2 core XLPE 8.36 mm2
4 core XLPE 13.5mm2
16mm2
2 core PVC 20.3mm2
4 core PVC 31.9mm2
2 core XLPE 13.5mm2
4 core XLPE 16.0mm2

But might be best to check the cable manufacturers information.

tigerpaul · Mar 21, 2012

Thanks chaps,

It is XLPE cable we're using, only short runs indoors. I'm going to try and get manufacturers details tomorrow and hopefully I'll be alright.

BruceB · Mar 21, 2012

There is a table on the earthingnuts website:
http://www.earthingnuts.co.uk/pdf/pvc_xlpe.pdf

Darkwood · Mar 21, 2012

Shouldnt be a problem at those small sizes but XPLE would need confirming i always use pvc also freindly word of caution Tiger! Watch your P's and Q's its a public forum and the Mods dont appreciate swearing on any level as it lowers the value of the site :38:

Engineer54 · Mar 21, 2012

Here you go, The figure in brackets are those cable that DON'T comply!! As you can see your fine all the way up to 95mm, on 2 core SWA cables...

Table for 90[SUP]0[/SUP]C Thermosetting SWA cables operating at 70[SUP]0[/SUP]C.

[TABLE="class: yiv1034213597MsoTableGrid"]
[TR]
[TD="width: 118"]

Conductor CSA

[/TD]
[TD="width: 118"]

Minimum CSA of SWA to meet 54G

[/TD]
[TD="width: 118"]

CSA of armour 2 core

[/TD]
[TD="width: 118"]

CSA of armour 3 core

[/TD]
[TD="width: 118"]

CSA of armour 4 core

[/TD]
[/TR]
[TR]
[TD="width: 118"]

1.5

[/TD]
[TD="width: 118"]

3.4

[/TD]
[TD="width: 118"]

16

[/TD]
[TD="width: 118"]

17

[/TD]
[TD="width: 118"]

18

[/TD]
[/TR]
[TR]
[TD="width: 118"]

2.5

[/TD]
[TD="width: 118"]

5.7

[/TD]
[TD="width: 118"]

17

[/TD]
[TD="width: 118"]

19

[/TD]
[TD="width: 118"]

20

[/TD]
[/TR]
[TR]
[TD="width: 118"]

4

[/TD]
[TD="width: 118"]

9.0

[/TD]
[TD="width: 118"]

19

[/TD]
[TD="width: 118"]

21

[/TD]
[TD="width: 118"]

23

[/TD]
[/TR]
[TR]
[TD="width: 118"]

6

[/TD]
[TD="width: 118"]

13.6

[/TD]
[TD="width: 118"]

22

[/TD]
[TD="width: 118"]

23

[/TD]
[TD="width: 118"]

36

[/TD]
[/TR]
[TR]
[TD="width: 118"]

10

[/TD]
[TD="width: 118"]

22.6

[/TD]
[TD="width: 118"]

26

[/TD]
[TD="width: 118"]

39

[/TD]
[TD="width: 118"]

43

[/TD]
[/TR]
[TR]
[TD="width: 118"]

16

[/TD]
[TD="width: 118"]

36.1

[/TD]
[TD="width: 118"]

41

[/TD]
[TD="width: 118"]

44

[/TD]
[TD="width: 118"]

49

[/TD]
[/TR]
[TR]
[TD="width: 118"]

25

[/TD]
[TD="width: 118"]

36.1

[/TD]
[TD="width: 118"]

42

[/TD]
[TD="width: 118"]

62

[/TD]
[TD="width: 118"]

70

[/TD]
[/TR]
[TR]
[TD="width: 118"]

35

[/TD]
[TD="width: 118"]

36.1

[/TD]
[TD="width: 118"]

62

[/TD]
[TD="width: 118"]

70

[/TD]
[TD="width: 118"]

80

[/TD]
[/TR]
[TR]
[TD="width: 118"]

50

[/TD]
[TD="width: 118"]

56.4

[/TD]
[TD="width: 118"]

68

[/TD]
[TD="width: 118"]

78

[/TD]
[TD="width: 118"]

90

[/TD]
[/TR]
[TR]
[TD="width: 118"]

70

[/TD]
[TD="width: 118"]

79.0

[/TD]
[TD="width: 118"]

80

[/TD]
[TD="width: 118"]

90

[/TD]
[TD="width: 118"]

131

[/TD]
[/TR]
[TR]
[TD="width: 118"]

95

[/TD]
[TD="width: 118"]

107.2

[/TD]
[TD="width: 118"]

113

[/TD]
[TD="width: 118"]

128

[/TD]
[TD="width: 118"]

147

[/TD]
[/TR]
[TR]
[TD="width: 118"]

120

[/TD]
[TD="width: 118"]

135.3

[/TD]
[TD="width: 118"]

(125)

[/TD]
[TD="width: 118"]

141

[/TD]
[TD="width: 118"]

206

[/TD]
[/TR]
[TR]
[TD="width: 118"]

150

[/TD]
[TD="width: 118"]

169.2

[/TD]
[TD="width: 118"]

(138

[/TD]
[TD="width: 118"]

201

[/TD]
[TD="width: 118"]

230

[/TD]
[/TR]
[TR]
[TD="width: 118"]

185

[/TD]
[TD="width: 118"]

208.6

[/TD]
[TD="width: 118"]

(191)

[/TD]
[TD="width: 118"]

220

[/TD]
[TD="width: 118"]

255

[/TD]
[/TR]
[TR]
[TD="width: 118"]

240

[/TD]
[TD="width: 118"]

270.6

[/TD]
[TD="width: 118"]

(215)

[/TD]
[TD="width: 118"]

(250)

[/TD]
[TD="width: 118"]

289

[/TD]
[/TR]
[TR]
[TD="width: 118"]

300

[/TD]
[TD="width: 118"]

338.3

[/TD]
[TD="width: 118"]

(235)

[/TD]
[TD="width: 118"]

(269)

[/TD]
[TD="width: 118"]

(319)

[/TD]
[/TR]
[TR]
[TD="width: 118"]

400

[/TD]
[TD="width: 118"]

451.0

[/TD]
[TD="width: 118"]

(265)

[/TD]
[TD="width: 118"]

(304)

[/TD]
[TD="width: 118"]

(452)

[/TD]
[/TR]
[/TABLE]

tigerpaul · Mar 22, 2012

Thanks chaps, gonna get on the case today.

tigerpaul · Mar 22, 2012

Looks like PVC cables would have been okay but as were using XLPE they are not... Typical!
Hopefully if I get moe info then the adiabatic equation might get me out of a hole..

Engineer54 · Mar 22, 2012

tigerpaul said:
Looks like PVC cables would have been okay but as were using XLPE they are not... Typical!
Hopefully if I get moe info then the adiabatic equation might get me out of a hole..

I've got 10mm 2 cores and 4 cores, for SP&N and TP&N DB's
Also 16mm 2 cores and 4 cores, for SP&N and TP%N DB's

What are you talking about?? Look at the table i posted again!!. ....The cables you mentioned above ALL conform with the minimal CSA required for your CPC!!!