davidbeach: the system you're talking about is TN-C: Terre et Neutre Confobdus or Combined EarthNeutral. It saves one conductor.
weh3: yes BS to me is British Standard - specifically BS7671 IEE Wiring Regulations 16th edition 2001 Amendment 2-2003 (which includes the new cable color code)...
davidbeach - tyvm :)
So what is the equivalent of IT, TT, TNC and TNS? NEC has only 1?
I follow BS and IEC - but whenver i can i try to value NEC as well. NFPA 70 is a little problematic for LV distribution when all products are to IEC and project speces in BS/CSI, but not for the rest of the...
Thanks rbulsara.
As per my first post, i agree with the step voltage and the increment of s.c. value.
I have made a little drawing on this page to explain what i mean:
http://lndang.tripod.com/
I am installing all condictors as per NEC - also as per my first post. It is only after i do so i...
Hi,
Thank you - so we agree it is only to prevent the s.c current be limited.
Ok, here's another: the earthing electrode near the load is connected to the earthing ring made of a bare 70mm2 copper cable buried @60cm depth all around the camp. This ring passes near the substation and the...
Hi,
I have a 100kVA load 300m far from the substation and i had to run 3 cores for the 3 phases and 1/2 core for the neutral and 1/2 core for earth.
I did install an earth pit near the load but i put the 1/2core cable as well so that the earth will not be the only return path for the fault...
I am sorry, for item 2: the solution with the software is to increase the size cable, not the breaker as i said above. Actually what it tells me is that it was unable to find a suitable breaker, i increase cable size manually and lock it and run simulation again and it gives me a breaker. The...
Hi,
I have 2 separate questions:
1. A project specifcations say that:
a. The transformer neutral shall be earthed to a bar, one tip of which linked to an earth pit and the other tip linked to the earthing ring around the premisses.
b. The neutral in the MDB shall be earthed (they say to help...