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.

 

[Des 56]

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

The above deosn't incude gas lighting though

 

[telectrix]

no but you need a supply of gas mantles.

 

[Des 56]

And a man with a flame and a pole

 

[SPARTYKUS]

Machine gun with tracer bullets?

 

[davelerave]

burp mistake
http://hagergroup.com.au/services/faq/84.htm

 

[Engineer54]

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

You can virtually say, any appliance or equipment, with a capacitor on the incoming supply will give a leakage current. Most electronic equipment will have supply filters, to protect the electronics against spikes, noise etc. Computers and other IT stuff will also employ these at a higher level, on the incoming supply. These will generally allow higher than normal leakage currents to flow directly to earth conductor, by the means they are connected between phase and neutral to earth...