Radials - earth return

[Electricalserv]

Does anybody put these in... What would the bods say?

 

[Deleted member 26818]

I doubt that they'll say anything, as they will have no idea what you are on about.

 

[Electricalserv]

Nice sarcasm!!!!

No seriously an extra returning earth cable from the final socket as per On-site guide

 

[telectrix]

what page is that on, mate

 

[Deleted member 26818]

I think you must be reffering to High Integrity Earthing, as used where there are expected to be high earth leakage, I believe 10mA or above.

 

[Electricalserv]

what page is that on, mate

Page 67-68. Where in normal use the protective conductor is likely to exceed 10mA

 

[Electricalserv]

I think you must be reffering to High Integrity Earthing, as used where there are expected to be high earth leakage, I believe 10mA or above.

Yes....is it only for that occasion or on every radial circuit...

 

[Deleted member 26818]

Only where the earth leakage is expected to be 10mA or above.
If there are two similar Radials, the CPCs can be linked to form a ring.

 

[Electricalserv]

Only where the earth leakage is expected to be 10mA or above.
If there are two similar Radials, the CPCs can be linked to form a ring.

In what cases can you expect a protective conducter to exceed 10mA though?

 

[telectrix]

where there are several pieces of IT equipment plugged in to the circuit e.g. 6 computers.

 

[Deleted member 26818]

I generally allow 3.5mA per computer, so 3 or more computers on a circuit and I will install high integrity earthing.

 

[Des 56]

where there are several pieces of IT equipment plugged in to the circuit e.g. 6 computers.

and some lighting circuits

 

[telectrix]

and some lighting circuits

still gas lighting up here.

 

[Electricalserv]

Sorry to be pedantic about this but can someone explain why 10mA flows because of computers and some lighting circuits...You learn something new everyday!

 

[telectrix]

power supplies in pc's. ballasts and control gear in lighting. all have leakage currents due to design.