What’s best practice terminating 2 earths

[Jako13!]

Hi guys what’s best practice when you’ve got a CPC and the fly lead of the swa for the armour and the cores are too big to terminate into the earth bar of a consumer unit?

 

[SparkySy]

Can you use a finger crimp or pin lug? They will reduce the diameter somewhat!

 

[Dustydazzler]

It is nor uncommon to just put half the cores in 1 terminal and the other half in the next terminal (assuming you have a spare terminal that is)

If not as above buy a finger lug crimp thingy

 

[SparkySy]

@Dustydazzler
It's funny I nearly suggested that option above but didn't know how it would go down on here so kept quiet, I have been known to do that in the past, don't really see anything wrong with it personally!

 

[Dustydazzler]

@Dustydazzler
It's funny I nearly suggested that option above but didn't know how it would go down on here so kept quiet, I have been known to do that in the past, don't really see anything wrong with it personally!

It is better than what most builders do which is to trim off half the cores so it fits

 

[westward10]

@Dustydazzler
It's funny I nearly suggested that option above but didn't know how it would go down on here so kept quiet, I have been known to do that in the past, don't really see anything wrong with it personally!

It suggests the conductor is oversized to enable suitable termination as per manufacturer recommendations. You have also divided the conductor into separate unequal csas.

 

[brianmoooore]

I think the OP means that the SWA has a core used as cpc, and the SWA gland/banjo has a lead connected to it, giving two separate wires which should go to the same terminal on the CU earth bar. These two wires might go into the terminal individually, but the two together are too big.
I would connect the SWA core to the correct terminal, and the banjo flylead to a spare amongst the bonding terminals.
Common sense has to take priority over the letter of the regs occasionally.

 

[westward10]

It is nor uncommon to just put half the cores in 1 terminal and the other half in the next terminal (assuming you have a spare terminal that is)

If not as above buy a finger lug crimp thingy

How would it be half. Assuming this is a seven strand conductor the split is 43% and 57% so not half which effectively results in parallel conductors of differing csa.

 

[pirate]

This interests me. Parallel conductors of different CSA. They will be parallel for about 10mm, connected to the same earth bar 10mm apart...would that be awful?

 

[westward10]

This interests me. Parallel conductors of different CSA. They will be parallel for about 10mm, connected to the same earth bar 10mm apart...would that be awful?

10mm or 10m it makes little difference in essence. BS7671 states parallel conductors shall be of the same csa and length, fault current or overcurrent will not think this is only 10mm so it should be fine.

 

[SparkySy]

It suggests the conductor is oversized to enable suitable termination as per manufacturer recommendations. You have also divided the conductor into separate unequal csas.

It does indeed, but over two terminals with mm between them even with a 43-57 split of probably 10mm or so maximum is it really going to cause an issue. Whilst I agree that it not best practice and as I suggested earlier a pin lug would be the best option, when In a fix it is a practical solution, and as Dusty says better than giving the conductor a haircut.
If you use an SWA cable with 1 core and the armor both used as earth then there will be a difference in the size of earth conductor for the whole circuit and unequal current under fault can flow.

 

[pirate]

Ah, ok...so it would be ok for the parallel CPCs to be inserted in a pin lug?

 

[SparkySy]

@pirate 2 pin lugs would be put on the separate conductors to reduce the size and then put into the same terminal.

 

[westward10]

It does indeed, but over two terminals with mm between them even with a 43-57 split of probably 10mm or so maximum is it really going to cause an issue. Whilst I agree that it not best practice and as I suggested earlier a pin lug would be the best option, when In a fix it is a practical solution, and as Dusty says better than giving the conductor a haircut.
If you use an SWA cable with 1 core and the armor both used as earth then there will be a difference in the size of earth conductor for the whole circuit and unequal current under fault can flow.

It may well not cause an issue but it creates parallel conductors of differing csa the length is not relevant. The suggestion of a swa core and sheath is totally different.

 

[timhoward]

I realise this isn't the main point of the thread - but while we are having confessionals asking hypothetical questions, in the situation where the CPC bar has run out of adequate terminals is it permitted to connect a new earthing conductor the same csa as the main earthing conductor with a ring terminal crimp onto main earth connection, and run this outside the CU to an external Kingsmill bar with more ring terminals, which are then in turn used for the problem new circuit that doesn't fit inside?