Live side

[Marlow]

Good evening,

a colleague of mine wants to install a sub main into the liveside of a mainswitch in another board.

Can people please provide me a answer if it ok or not

thanks

 

[davesparks]

Too many variables to give a reliable answer.
IF the main switch terminals are designed to accept two conductors, and IF it is already fed from a submain and The new cable is the right size for the OCPD of that submain. Also if that existing submain has spare capacity to feed this new submain then it might be ok.

 

[Richard Burns]

Not really, you should have a single point of isolation, and whilst it may be possible to fit two sets of tails into the switch (2X25mm² is a bit tight even on a 50mm² capacity terminal) it is not good practice.
Use an isolator and a Henley block.

 

[Marlow]

Thanks for the reply

The board is a small board 63/100 amps fed from around 60/70 meters away.
the supply for the new board is 63 amps.

Personally I think it shouldn't be done but designer said it is ok

 

[Richard Burns]

So long as the designer has put that in writing and signed it then crack on.

 

[davesparks]

Not really, you should have a single point of isolation, and whilst it may be possible to fit two sets of tails into the switch (2X25mm² is a bit tight even on a 50mm² capacity terminal) it is not good practice.
Use an isolator and a Henley block.

You're assuming its a 100A board at the intake then?
If it's already fed via a submain then it is possible.

 

[tomspark93]

so is the existing cable suitable for the added design current of the new board? What about terminating the existing into a switch disconnector and then taking two feeds to the separate boards?

 

[Marlow]

You're assuming its a 100A board at the intake then?
If it's already fed via a submain then it is possible.

It will be coming from a large board located in switch room cannot gain access at the moment

Richard it is been added onto the plans so we will be covered but I am questioning it because don't each circuit need a way of isolation

 

[Marlow]

so is the existing cable suitable for the added design current of the new board? What about terminating the existing into a switch disconnector and then taking two feeds to the separate boards?

The cable is should be suitable as we need 63 amp supply
I think I will advise the disconnector option as the small board they want us to come off is redundant

 

[davesparks]

If it's redundant then remove it and through joint the submain.