agricultural tt earth

Simon-0116 · May 18, 2014

Just been to look at a job subing to grain drying firm to help then installing cables, lighting etc. The mains is 3ph in house, across newly tarmac to a small out house were it goes to db, then off to variouse sub dbs. The main swa from house is 16mm 4 core, swa as earth. ( No 300 / 500ma main switch in house.) From here it will run to the main board to the new grain shed. There electrican says put 300ma main switch on db in grain store and make it to tt, (as they havent priced to altet anything) But I thought it should be a source. So I proposed making main swa in to tt system / eart rod / 300 ma, then all of farm protected and wont trip the current farm house. Ah this is a arable farm, no livestock ever present, am I right or totally wrong and should keep my thoughts to my self

GLENNSPARK · May 18, 2014

i`l have a look round for an up to date one......

if someone has a link ...that`l save me a bit of effort....

Engineer54 · May 18, 2014

16mm 4 core is actually 49mm not 50mm, but the 50mm is as near as dam it!! lol!!

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

Conductor CSA	Minimum CSA of SWA to meet 54G	CSA of armour 2 core	CSA of armour 3 core	CSA of armour 4 core
1.5	3.4	16	17	18
2.5	5.7	17	19	20
4	9.0	19	21	23
6	13.6	22	23	36
10	22.6	26	39	43
16	36.1	41	44	49
25	36.1	42	62	70
35	36.1	62	70	80
50	56.4	68	78	90
70	79.0	80	90	131
95	107.2	113	128	147
120	135.3	(125)	141	206
150	169.2	(138)	201	230
185	208.6	(191)	220	255
240	270.6	(215)	(250)	289
300	338.3	(235)	(269)	(319)
400	451.0	(265)	(304)	452

Engineer54 · May 18, 2014

Here you go Glenn....

Blue = min CSA of cables SWA to comply.

(Red) = Cable does not comply.

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

Conductor CSA	Minimum CSA of SWA to meet 54G	CSA of armour 2 core	CSA of armour 3 core	CSA of armour 4 core
1.5	3.4	15	16	17
2.5	5.7	17	19	20
4	9.0	21	23	35
6	13.6	24	36	40
10	22.6	41	44	49
16	36.1	46	50	72
25	36.1	60	66	76
35	36.1	66	74	84
50	56.4	74	84	122
70	79.0	84	119	138
95	107.2	122	138	160
120	135.3	(131)	150	220
150	169.2	(144)	211	240
185	208.6	(201)	230	265
240	270.6	(225)	(260)	299
300	338.3	(250)	(289)	(333)
400	403.9	(279)	(319)	467

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

Conductor CSA	Minimum CSA of SWA to meet 54G	CSA of armour 2 core	CSA of armour 3 core	CSA of armour 4 core
1.5	3.4	16	17	18
2.5	5.7	17	19	20
4	9.0	19	21	23
6	13.6	22	23	36
10	22.6	26	39	43
16	36.1	41	44	49
25	36.1	42	62	70
35	36.1	62	70	80
50	56.4	68	78	90
70	79.0	80	90	131
95	107.2	113	128	147
120	135.3	(125)	141	206
150	169.2	(138)	201	230
185	208.6	(191)	220	255
240	270.6	(215)	(250)	289
300	338.3	(235)	(269)	(319)
400	451.0	(265)	(304)	452

For CPC purposes ''ONLY''. Do not use where BONDING is also a requirement....

GLENNSPARK · May 18, 2014

Engineer54 said:
Here you go Glenn....

Blue = min CSA of cables SWA to comply.

(Red) = Cable does not comply.

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

Conductor CSA

Minimum CSA of SWA to meet 54G

CSA of armour 2 core

CSA of armour 3 core

CSA of armour 4 core

1.5

3.4

15

16

17

2.5

5.7

17

19

20

4

9.0

21

23

35

6

13.6

24

36

40

10

22.6

41

44

49

16

36.1

46

50

72

25

36.1

60

66

76

35

36.1

66

74

84

50

56.4

74

84

122

70

79.0

84

119

138

95

107.2

122

138

160

120

135.3

(131)

150

220

150

169.2

(144)

211

240

185

208.6

(201)

230

265

240

270.6

(225)

(260)

299

300

338.3

(250)

(289)

(333)

400

403.9

(279)

(319)

467

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

Conductor CSA

Minimum CSA of SWA to meet 54G

CSA of armour 2 core

CSA of armour 3 core

CSA of armour 4 core

1.5

3.4

16

17

18

2.5

5.7

17

19

20

4

9.0

19

21

23

6

13.6

22

23

36

10

22.6

26

39

43

16

36.1

41

44

49

25

36.1

42

62

70

35

36.1

62

70

80

50

56.4

68

78

90

70

79.0

80

90

131

95

107.2

113

128

147

120

135.3

(125)

141

206

150

169.2

(138)

201

230

185

208.6

(191)

220

255

240

270.6

(215)

(250)

289

300

338.3

(235)

(269)

(319)

400

451.0

(265)

(304)

452

Ta..

here...:

have your self a likes n thanks...

Knobhead · May 18, 2014

I won’t bother e-mailing stuff to you in future Glenn, you don’t look at it.
You’ve had that table for well over a year.

Rockingit · May 18, 2014

Right - at the risk of an amount of ridicule, I'm now confused. I'm either had too many ciders in the sunshine or am just not reading those tables right: We've got 16mm conductors, which means we need a cpc of 1/2 16 = 8mm. We've got TN-S so we need to satisfy 544.1 and therefore need to be somewhere between 6mm and 25mm for a bonding conductor. That table says we've got a csa eq of 49mm, yes? So where's the problem?!

atm84 · May 18, 2014

Rockingit said:
Right - at the risk of an amount of ridicule, I'm now confused. I'm either had too many ciders in the sunshine or am just not reading those tables right: We've got 16mm conductors, which means we need a cpc of 1/2 16 = 8mm. We've got TN-S so we need to satisfy 544.1 and therefore need to be somewhere between 6mm and 25mm for a bonding conductor. That table says we've got a csa eq of 49mm, yes? So where's the problem?!

There ain't one. The old boys got muggled up. The armouring of a 16mm2 4 core is sufficient as a cpc and bonding conductor but I always run a separate conductor as don't like to have to rely on a gland. (however by regulations you would be fine not to run a separate conductor- testing permitted and satisfactory results obtained obviously)

GLENNSPARK · May 18, 2014

Tony said:
I won’t bother e-mailing stuff to you in future Glenn, you don’t look at it.
You’ve had that table for well over a year.

yeah....well if your gonna be like that you miserable old goat...

jamie-spark · May 18, 2014

Rockingit said:
Right - at the risk of an amount of ridicule, I'm now confused. I'm either had too many ciders in the sunshine or am just not reading those tables right: We've got 16mm conductors, which means we need a cpc of 1/2 16 = 8mm. We've got TN-S so we need to satisfy 544.1 and therefore need to be somewhere between 6mm and 25mm for a bonding conductor. That table says we've got a csa eq of 49mm, yes? So where's the problem?!

The problem is if there is extraneous conductive parts in the grain shed . Then it requires to be the copper equivalent. So steel 8/1

[ElectriciansForums.net] agricultural tt earth

jamie-spark · May 18, 2014

atm84 said:
There ain't one. The old boys got muggled up. The armouring of a 16mm2 4 core is sufficient as a cpc and bonding conductor )

Are you 100% sure ?
Have a look at the table above

Rockingit · May 18, 2014

jamie-spark said:
The problem is if there is extraneous conductive parts in the grain shed . Then it requires to be the copper equivalent. So steel 8/1

View attachment 24726

That's what I mean about not being clear on exactly WHICH csa is being used in the tables - because if some of them don't comply then that suggests they have already been converted steel > copper. And if we've got STEEL at 49, then we've only got a Cu eq of 6mm (which goes back to my original remark about using the adiabatic to see if it complies as earthing conductor or not).

Rockingit · May 18, 2014

jamie-spark said:
Are you 100% sure ?
Have a look at the table above

That's for TN-C-S, not TN-S

atm84 · May 18, 2014

Never 100% certain. Ill whack it into the havacomp and see what that suggests.

jamie-spark · May 18, 2014

Rockingit said:
That's for TN-C-S, not TN-S

Correct

Where did he say it was tns

atm84 · May 18, 2014

Rockingit said:
jamie-spark said:

The problem is if there is extraneous conductive parts in the grain shed . Then it requires to be the copper equivalent. So steel 8/1

View attachment 24726

Click to expand...

That's what I mean about not being clear on exactly WHICH csa is being used in the tables - because if some of them don't comply then that suggests they have already been converted steel > copper. And if we've got STEEL at 49, then we've only got a Cu eq of 6mm (which goes back to my original remark about using the adiabatic to see if it complies as earthing conductor or not).

They are converted values!

agricultural tt earth

Simon-0116

-

GLENNSPARK

Engineer54

Engineer54

GLENNSPARK

Knobhead

Rockingit

-

atm84

-

GLENNSPARK

jamie-spark

-

jamie-spark

-

Rockingit

-

Rockingit

-

atm84

-

jamie-spark

-

atm84

-

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