RCD protection on a second distribution unit in work shed

[RobMax]

Planning on putting in a sub-main across garden into a workshed to accommodate socket circuit with workshed, garden lighting and pond pump. It will be protected at main c/u on an RCD would it also be necessary / advisable to have further RCD protection in the workshed?

 

[i=p/u]

rcd's inline can be problem with nuicene trippin, why not just come off mcb to new board in shed and protect withwith rcd there or rcbo..

what about earthing

 

[RobMax]

Thanks for that.

I was thinking that an earthing rod would be the best option.

 

[i=p/u]

well think they reccomend that, and depends on earthing system.
remember they like good discrimination of devices ratio of 2/1 is rule of thumb, like 40A breaker in house and 20 in shed .just example

 

[MarkieSparkie]

Do a search for 'exporting the earth' on the forum you'll probably change your mind. about using an earth rod.

 

[pushrod]

well think they reccomend that, and depends on earthing system.
remember they like good discrimination of devices ratio of 2/1 is rule of thumb, like 40A breaker in house and 20 in shed .just example

You need protective devices/mcbs that are larger than the design currents but that will still protect the cables. ie the current carrying capacity of the cable, when all simultaneous rating factors have been applied, must be greater than the rating of the protective device (In).

If 2 ordinary RCDs are in series there is no discrimination between them.

As i=p/u said, it is best if you can arrange to have the rcd at the new submain - easier to test and reset, and also not taking out half the house's circuits if it trips

 

[brucelee]

use swa to supply shed from a unprotected circuit at the origin and put 30 mA rcd in shed only and you dont need the rod unless there is extraneous conductive parts coming into the shed such as water /gas/ oil pipes etc

if using 3 core swa and the third as the cpc then only earth the armour of the swa at the origin

 

[RobMax]

Did search as MarkieSparkie suggested (long thread) and will think again. Like brucelle suggestion. Thanks for all for comments.

 

[telectrix]

brucelle? sex change or .... what?

 

[SimpleSimon]

rcd's inline can be problem with nuicene trippin, why not just come off mcb to new board in shed and protect withwith rcd there or rcbo..

what about earthing

Smartest thing I've heard you say. Well done

 

[i=p/u]

simple when you know how, problem is its not practical, think im gonna up my game and take more chances and rely on you guys when i fuk up..

 

[pushrod]

simple when you know how, problem is its not practical, think im gonna up my game and take more chances and rely on you guys when i f*** up..

Well you are the only one to be thanked by the OP - so there's progress

 

[i=p/u]

didn't notice but what can i say im learning to be serious

 

[telectrix]

you cannot be serious, the ball was in!

 

[i=p/u]

it wasnt a 4 it was a 6, umpires arms went up