Not seen this before ??

[KEVINDOE]

Hi everyone...
I was hoping for some advice on a circuit to a summerhouse that was part of a p.i.r. i have been doing today,
There was a garage type unit with the usual two ways for sockets and lighting, metal clad, and the sub main is 6mm s.w.a., this end is on a TT rodded down well with a reading of 31 ohms, the s.w.a is under ground and makes its way back to the main consumer unit and into a connection box on the outside of the house where the armour is terminated, conductors then pass through the walls in 20 mm conduit from the back of the external connection box into a cooker control switch so that the homeowner can isolate the summer house from inside the house.. s.w.a connect into secondary side of cooker switch and c.p.c terminates into earth terminal as norm...now ...the switch is next to the c.u., and running from an 32 amp breaker, are line and neutral, but no c.p.c, to the primary side of the cooker switch,ther are no r.c.ds on main c.u.... is there anything i should be noting here??( regarding the sub main that is)

Thanks in advance,,
Jemma

 

[Guest123]

So, if I'm reading it correctly, a L-E short circuit on the SWA sub-main wouldn't cause any upstream device to operate as there is no earth fault path back to the main CU in the house???

If for example someone were to damage the SWA with a spade bewteen L-E, no device would operate to shut off the supply at the house as there isn't a cpc connected to the armouring.

 

[Richard Burns]

Only things I can think of:
Is the garage CU in the summer house 30mA RCD protected as you have sockets there and on a TT.
Is the CPC from the SWA to the cooker switch of suitable size for the installation.
Is there discrimination between the 32A breaker in the CU and the breaker for the sockets in the summer house.

Just seen Lenny's post yes you would need an upfront RCD 100mA typeS in the house.

 

[KEVINDOE]

Thanks lenny..
Its a pme supply and it looks like someone has tried to make the whole lot tt to supply the summerhouse

 

[KEVINDOE]

Richard,,thanks for your reply..cpc is 6mm...sockets are at 16amp..and yes 30ma rcd tested ok

 

[KEVINDOE]

So my best option is to install c.p.c from c.u. to primary of cooker switch side and and have the lot as pme ? leave the rod in as back up ? no utilitys present by the way

 

[Richard Burns]

Sounds good

 

[KEVINDOE]

On my to do list for tomar...thanks guys