Copper equivalent to SWA armour

[Kg85]

Ive got a copy of this table, but not sure where it was derived from?? Has anybody else seen/used this table??

 

[Engineer54]

Throw it away it's wrong!! All SWA cables from 2 core to 4 core up to 95mm will comply with min CSA for use as the cables CPC. Main bonding requirements is a different matter, and should not be confused with sole use as CPC...

Copper has a conductance of approx 8 times that of steel...

 

[Engineer54]

Here use these two tables, tried tested and proven... lol!!

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 ​

​

​

 

[Engineer54]

Just noticed, that table you posted is relating to ''Thermal Setting insulation'' cable operating at 90 C, which you can count on experiencing once in a blue moon. The thermal setting insulation cable table in my example, has beeen suitably adjusted to operating at 70 C. Not that you'll probably ever see a typical SWA cable operating even close to that sort of temperature either!!

That above table is like the wirenut table that's been doing the rounds since the late 70's, in being basically misleading, confusing, and pretty much useless for 99% of installations....

Anyway that's the reason why they are giving over the top values for min CSA to comply with table 54G.

 

[Farmelectrics]

rule of thumb anything over 95mm2 requires a seperate cpc or thats whats allways stuck in my head lol

 

[Engineer54]

rule of thumb anything over 95mm2 requires a seperate cpc or thats whats allways stuck in my head lol

Look at the table, as that rule of thumb would only apply to 2 core SWA cables....

 

[Bobster]

Also and I know this should be bloody obvious, but make sure you still work out what the Zs is going to be at the end of the cable. Only really becomes an issue on longer runs.

The Armour is all well and good being a CPC, but if you can't meet disconnection times...

 

[Jonspark]

Also and I know this should be bloody obvious, but make sure you still work out what the Zs is going to be at the end of the cable. Only really becomes an issue on longer runs.

The Armour is all well and good being a CPC, but if you can't meet disconnection times...

how would you go about calculating R2 of an SWA ?

 

[Bobster]

Same as you would a normal circuit.

Just use a correction factor in that the armor isn't as conductive as copper.

 

[Jonspark]

What like find the csa of armour then x8 ?

 

[Jonspark]

Any ideas anyone?

 

[GEOFF S]

how would you go about calculating R2 of an SWA ?

No correction factor needed, just the impedance. So just calculate the impedance and multiply by length.

Cheers

 

[Jonspark]

Face palm time