OP
swifters
What is the Zdb?
Discuss TNCS Outbuilding earthing arrangement in the UK Electrical Forum area at ElectriciansForums.net
Why would your Zdb need to meet the max Ze reading??
Its a sub main.....
If you are splitting from a Henley then you do.
If from a CB then you need to stay within the Zs for the CB.
What is the Zdb?
comments in red.Thanks guys. Four questions.
1. Is it saying that if your making the outbuilding a TT system and you're supplying said outbuilding with an armoured cable, then don't earth the armour at all as so not to cross PME earth from dwelling with the TT earth of outbuilding. So SWA Armout is not earthed at all?? if TT'ing the outhouse you just earth the SWA armour at the supply end
2. When keeping outbuilding within the PME EZ and the outbuilding has extraneous parts, is it saying to run a 10mm earth seperate to the supply cable of the outbuilding to connect a designated 10mm earth from extraneous parts in OB to MET of dwelling?? Or can you just bond parts with a 10mm earth to the MET of the outbuilding which is ultimately fed from dwelling. a pme earthing system needs 10mm bonding due to the high fault currents in bonding conductors are liable. if a 10mm 3 core SWA is used, then it will comply
3. I've been told that the dwelling should made into a TT as the sockets within could be used to plug in an extension lead which means you could potentially come into contact with something far away from the outhouse which could be extraneous but surely there's no difference from an outside socket attached to the dwelling itself?? Confusing!!!
4. What about if the dwelling has a TNS or TT earthing arrangement? Why is PME more dangerous.
Thanks for comments but it's thrown a few more questions up. Haha. If you Earth the armour at supply end are you saying to not connect armour into gland at outhouse end as surely If its a metal CU then it will be all connected to TT side as well. And for the second comment your saying a 10mm 3c Can use one of the cores for the CPC of the submain plus the adequate bonding requirements for extraneous parts of the outhouse?
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