pnb

[maguire]

I may have raised this before, has any one any info on a pnb system I have read plenty of descriptions saw plenty diagrams, however in this instance the supply comes to a all steel building and the dno guys say they will not provide an earth, at all, period. I have asked if this can be treated as a TT system all I got was em, eh, no it's a pnb. phoned the head office was told to hang on after I explained what I wanted clarification on, the phone went dead, I have e-mailed, twice, I have now thought of a solution thus: Weld a lug to the steel uprights, 16 mm from CU to lug then out to as many spikes as it takes making it a TT
Dev

 

[holmslaw]

..

 

[maguire]

Hi No it's PNB protected neutral bonding term is used for local pole mounted tranny's
Dev

 

[GaryMo]

It's something I hadn't heard of either but it exists. It's a variation of TN-C-S:

PNB

 

[333rocky333]

Your other post was here

//www.diynot.com/forums/viewtopic.php?p=1499490#1499490

 

[maguire]

cheers I thought i was on here rocky and that was a good link gary the point of confusion is that it shows an earth link the the N side of the switch ?? cant be right can it
Dev

 

[shetland]

PNB is a variation of TNS which is used when only one customer is supplied from the transformer. The neutral-earth link instead of being at the DNO fusepanel and connected to the LV substation earthing system, is connected to the customers means of earthing at the MET.

 

[maguire]

Going by what Shetland says maybe this why they have refused to provide an earth, untill they see what provisions have been made at the installation

 

[ricicle]

Our site is PNB. Although classed as TNC-S is is often mistaken for PME. As this is not the case the tighter constraints of earthing and bonding associated with PME can be ignored.

 

[maguire]

Ricicle ta for that, I have just found out from the DNO that they will never supply earth to any metal building that houses livestock it must be TT with the ubiquitous 100mA trip why the line guys could'nt say that I will never know would have saved me a shed load of time
Dev