Garage Supply Questions

[Markyd180]

Hi everyone.

I am currently wiring a garage that is not joined to the property, its about 12 meters at the bottom of the garden.

The house supply is PME. I have been told by my cps provider that I am not to extend the earth and I must TT the garage.

I have run 6mm twin and earth from a rcd protected 32 amp mcb in the main consumer unit, through the house (the garden is on the other side of the house), through an external wall into a wiska box, then connect up SWA, run underground to the garage into a small consumer unit. I have earthed the armour at the house side. In the garage I have terminated the SWA in a plastic box with a nylon gland, connected it to a short piece of 6mm t and e, run in conduit into the garage cu main switch.

Now my problems begin. As I stupidly ran twin and earth from the board (it was a lot easier and cheaper than getting SWA all the way through the house), I have to keep it RCD protected at the main board.

Obviously I then cannot put an RCD in the garage which is TT'd.

Is it allowed to keep the house end on an RCD and just have a main switch in the garage, even though the garage is TT'd?

Hope this makes sense. Any advice/criticism gratefully received.

Thank you

 

[Baddegg]

Why can’t you export the pme, are there extraneous parts in the garage?

 

[buzzlightyear]

where's Pete with is drawings .

 

[telectrix]

it's OK< but a fault in the garage means going back to house to rest. is the T/E buried < 50mm in wall, or surface?

 

[Baddegg]

Can you alter the house Cu to put the sub dB mcb so as it’s not covered by rcd? And then protect accordingly at the garage if you have to TT...
Making an assumption that the 6mm t&e is under the floor and not chased in a wall?

 

[buzzlightyear]

https://dxu3qlulsm4jd.cloudfront.ne...hers/6/2005101314414308iee_outdoor_wiring.pdf its ok Pete found it ,thier was sweat coming of my head then .LOL.

 

[Markyd180]

Thanks everyone. At the moment the t and e is running behind plinth/cupboards/ovens etc in kitchen, clipped direct.

The are no extraneous parts but the cps provider told me as its a concrete floor they want it tt'd

 

[buzzlightyear]

The are no extraneous parts but the cps provider told me as its a concrete floor they want it tt'd

who is your scam .

 

[buzzlightyear]

read guidance note 8.earthing and bonding .

 

[davesparks]

Thanks everyone. At the moment the t and e is running behind plinth/cupboards/ovens etc in kitchen, clipped direct.

The are no extraneous parts but the cps provider told me as its a concrete floor they want it tt'd

I sometimes think the NICEIC etc say this sort of thing just to see whether their members actually understand the science and regulations or if they just blindly do whatever they are told without thinking.

 

[The Ghost]

Why can't you RCD at the TT end?

 

[Nigel]

I am all for helping each other but I do wonder what mess we are in where we have a qualified electrician that is unable to wire electric to a shed without scheme help and asking on a forum.

Op - do you have access to BS7671:2018? If so where have you looked so far?

 

[jackhammerJIM]

The are no extraneous parts but the cps provider told me as its a concrete floor they want it tt'd

My kitchen has a concrete floor and PME earthing is not prohibited

 

[DPG]

I'd love to see them back the concrete floor idea up with a reg. number.

 

[jackhammerJIM]

who is your scam .

My moneys on STROMA