SWA used as CPC

Engineer54 · Aug 23, 2013

darkwood said:
The table is correct 100% correct... as for confusing im not sure what you mean as long as you de-rate your XLPE to 70c as it clearly states 90c .... please dont tell me we have to further simplify these things wheres the technical part gone from been an Electrician if they never do the calculations and get drip fed all the answers how can their be any competence anymore....
Ill agree though i should have pointed that out about the Temp' de-rating on the XLPE may show compliance using the adiabatic equation where due to the 90c rating it shows as a non-compliance.

That earthnuts table has been around forever and a day, and to my knowledge has never been updated since the 80's!! So are you sure, it's 100% correct?? What's the point of having a table if you are going to have to recalculate every value it gives you?? Surely tables are for convenience, i can quite happily calculate for all the values i need, as should all competent electricians. Doesn't mean that a convienient table isn't going to be usefull to electricians and the like.

I've been using this table for a few years now, it has been updated and has taken most of the need for re-calulation away. That's if we are looking at SWA being used solely as the CPC, and not as the main earthing conductor, that will be also be catering for main bonding conductors of extraneous services and metalwork....

Blue = min CSA of cables SWA to comply.

(Red) = Cable does not comply.

Table for 70[SUP]0[/SUP]C Thermoplastic PVC SWA cables.

[TABLE="class: yiv9896119791cms_table_yiv1559363916MsoTableGrid"]
[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"]

15

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

16

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

17

[/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"]

21

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

23

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

35

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

6

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

13.6

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

24

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

36

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

40

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

10

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

22.6

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

41

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

44

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

49

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

16

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

36.1

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

46

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

50

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

72

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

25

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

36.1

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

60

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

66

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

76

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

35

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

36.1

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

66

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

74

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

84

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

50

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

56.4

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

74

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

84

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

122

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

70

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

79.0

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

84

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

119

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

138

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

95

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

107.2

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

122

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

138

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

160

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

120

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

135.3

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

(131)

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

150

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

220

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

150

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

169.2

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

(144)

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

211

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

240

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

185

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

208.6

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

(201)

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

230

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

265

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

240

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

270.6

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

(225)

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

(260)

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

299

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

300

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

338.3

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

(250)

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

(289)

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

(333)

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

400

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

403.9

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

(279)

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

(319)

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

467

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

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

[TABLE="class: yiv9896119791cms_table_yiv1559363916MsoTableGrid"]
[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]

Notice, that the 90'c thermosetting cables table, has already been adjusted for 70'c operation...

netblindpaul · Aug 23, 2013

Engineer54,
Those tables are virtually identical to the ones I suggested in my earlier post, (#14), that is the tables in GN1 appendix D, specifically, D9, D10a & D10b, yours being 9 & 10b.
However, the references have not been updated as table 54G is no more it is now 54.7, which to be honest is the only difference I found in skimming across both sets.
So, having not checked the earthing nuts table, yours are pretty much correct with the new reference for the 17th

Darkwood · Aug 23, 2013

E54 i agree with what you say and as the set you printed they are identical for PVC but obviously adjusted for XLPE .... i have the 90c table in my own ref' books and ive put in the brackets the 70c rating many yrs ago but as for ease of throwing up a table in the post i put the previous example up .... now you point out it can give confusion its been noted but the way i was taught was to to interpret all the information i was presented with and it is clear in stating 90c so i didn't give it a second thought.

Im not aguing your response im in somewhat of agreement since you pointed out the confusion it may cause but it hasn't been updated at all its the old table still stands as correct however to simplify XLPE values these are now expressed at 70c for easy comparison .... the 90c still serves a purpose to those who buy the XLPE and need to work to the cables max temp value (as rare as that may be)...... as you know i do the odd control system and most of my wiring especially for temp' monitoring and element feeds are tabled for their ratings at their max working temp ....it would be a nightmare if everything was streamlined to 70c although i can agree it does make better sense for the swa values for earthing.

Engineer54 · Aug 24, 2013

All i'm saying is, as far as SWA cables go, if you're going to use a convenient compliance table, you want to be able to use that table without the hassle of having to recalculate. That earthnuts table is at best confusing, and at worst, just not worth the hassle of keeping it to hand, as i say, i'd bin it!! (i binned mine years ago). You may just as well do the calculations from the word go. ...lol!!