TNS/TT combined

[sparks1653]

i have just been to carry out a site visit for a possible project. the house has an 80A TNS supply. there is a studio built in the garden that has just been wired, there are mistakes everywhere...for example main supply is 2.5mm cable supplying a 63a board.... the list continues. anyway the owner said the electrician also fitted an earth spike which i didnt expect as the ZE from the studio was way to high. after fitting an earth spike he recorded a reading of 25.8 ohms on the minor works cert. my knowledge of TT is limited as i dont really ever deal with it in london. should i remove the spike all together as im going to replace the cable to the studio anyway so could run a higher CSA earth cable as well to then be connected to the MET, what are the resistance reading regs for TT? i will start by taking a Ze measurement from the main house which i didnt get a chance to do today

 

[acvc]

Get the house converted to PME for a start, then see the sticky thread on 'Exporting PME to Outbuildings'. Factors like whether the outbuilding has gas/water supplied, i.e. extraneous conductive parts, will determine what you can do.

Any TT Ze over 200ohms needs to be investigated as it could be unstable. Its all in the OSG and Big Red (Green now) Book sparks 1653.

 

[Engineer54]

Get the house converted to PME for a start, then see the sticky thread on 'Exporting PME to Outbuildings'. Factors like whether the outbuilding has gas/water supplied, i.e. extraneous conductive parts, will determine what you can do.

Are you for real?? convert a TN-S for PME?? Think you should read the OP post again, you got lost somewhere along the way!!!