pcs on ring main

[Chr!s]

You need to consider section 543.7 as Des stated. 30 pcs will generate a high protective conductor current along with other office equipment. imagine if you have 30 mA and the protective conductor fails.

Regards chris

 

[Knobhead]

didnt have the balls to say told you so but was laughin inside

Coward!

 

[Farmelectrics]

chris i have read section 543.7 circuts are ring mains so what other means of earthing do you mean its all in dado trunking so obviously cant use containment as earth are you saying run another eart in as well as ring earth please educate me

 

[IQ Electrical]

Have a read of this guide, specifically the termination of the CPCs in a ring circuit with high protective conductor current:

 

[Farmelectrics]

thanks iq

 

[Farmelectrics]

iq what would you advise we have now removed the circuts from rcbo type to 32a mcb we are this saturday pulling in another 3 ring mains having read the info you posted am i right in saying that i need to pull another 4mm earth to every socket or in your experience how would you solve the above problem thanks in advance

 

[IQ Electrical]

Try to stick with a 'rule of thumb' number of 10 'workstations' per ring final circuit, this has always worked for us and in practice, earth leakage is mostly below 1mA per 'workstation'.

I define a workstation as a PC and associated monitor.

If this is a commercial environment then we would not be using RCD protection on these circuits/sockets.

Generally speaking, if the installation falls within the Electricity At Work Regulations 1989 then your design can be based on the assumption that a system is in place to ensure that workplace equipment is maintained and safe. This will not be the case if members of the public can use the sockets.

So, you can increase the number of circuits to suit and make sure that the ring final CPCs are terminated separately throughout the circuit as in the diagram on the PDF above.