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what type of wiring system do I have
Posted: Sat Sep 15, 2007 12:16 pm
by eddie
My house electric supply is fed from an overhead line cable with 2 cores, what type of system is this? TT, TNS TNC or what.
It has no in coming earth as such so as I understand I'll have to run a 16mm earth from earth bar in comsumer unit to an earth rod and 2 x 10mm earths to my water & gas.
any help cheers
Posted: Sun Sep 16, 2007 9:18 am
by Add
Hi,
You have a TT system. Your whole consumer unit must be protected by an RCD. 16mm to the earth rod 10mm to the gas and water also sound right. Remember limitations under part P.
Add
Posted: Sun Sep 16, 2007 7:18 pm
by cm
oops
Posted: Sun Sep 16, 2007 7:54 pm
by sparx
Hi if you are using an earth rod then it must read lower than 100 Ohms to fully comply with all requirements, & must also cover ALL circuits not just power!
standard best-practice is to change main sw. for time delayed 'S' type RCD, idealy of 100mA rating to give tripping discrimination. Cheaper/easier way may to ask supply company to provide earth from Neutral block instead of rod which would not require any RCD changes, most overhead systems work this way & would become PME/TN-C-S.