Help required on separate or non separate CPC for 200A 3P supply

[Wiredspark]

Hi guys, Im banging my head off the wall on this one. I have to run in a new 200A per phase supply. The cable length is 35M. Ambient temp is 20C. I am looking at table 4D4A in BGB and as it's to be on tray so Im thinking a 70mm CSA 4core as it has a Current carrying capacity of 207A (I am thinking this is a little neat so Im tempted more towards a 95mm) however, when I look at the armouring to see if the CSA will be sufficient as the earth I notice that the CSA of 95mm does not comply but the CSA of the 70mm does. Any help much appreciated.

 

[Bobster]

Work out what size a CPC you need using the adiabatic equation, then see what the steel equivalent will be, then see what the cross section of 95mm armour is.

 

[davesparks]

The last 200A submain I did was a lot more economical to run 2 cables in parallel, think the calcs came out at 2x25mm but can't be sure off the top of my head.

 

[Engineer54]

Hi guys, Im banging my head off the wall on this one. I have to run in a new 200A per phase supply. The cable length is 35M. Ambient temp is 20C. I am looking at table 4D4A in BGB and as it's to be on tray so Im thinking a 70mm CSA 4core as it has a Current carrying capacity of 207A (I am thinking this is a little neat so Im tempted more towards a 95mm) however, when I look at the armouring to see if the CSA will be sufficient as the earth I notice that the CSA of 95mm does not comply but the CSA of the 70mm does. Any help much appreciated.

A 4 core 95mm SWA cable armouring '''Will'' comply for the circuits CPC!! Throw that wirenuts table in the bin where it belongs!! Use this table for CPC compliance.

However these tables are for CPC compliance only, they do not refer to main bonding compliance....

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​

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