external consumer unit...

[equinox]

hi chaps, ive got to run an armoured cable down to a new consumer unit in an 'outbuilding'. on the comsumer, should i use an RCD incomer? on the diss board? Ive not done this sort of thing before so i assume i just come out of the diss board in the main building on a spare breaker and down to the new diss board. Also i have to run two armoured cables out to ponds, i assume these will have to be RCD protected as they are outside?

thanks chaps

 

[Mac]

hi chaps, ive got to run an armoured cable down to a new consumer unit in an 'outbuilding'. on the comsumer, should i use an RCD incomer? on the diss board? Ive not done this sort of thing before so i assume i just come out of the diss board in the main building on a spare breaker and down to the new diss board. Also i have to run two armoured cables out to ponds, i assume these will have to be RCD protected as they are outside?

thanks chaps

Can you not put a 63A isolator by the main CU feeding the outbuilding CU.Reason be if it trips in the outbuilding it will trip at the main CU,and then take your 2 SWA to the pondsThey will have to be RCD protected if run outside

 

[Phaeton]

Guys, correct me if I'm wrong, you will also need to provide a separate earth for the garage/outbuilding CU & not take it from the main CU.

Alan...

 

[equinox]

so... if i was to put a 63A isolator next to the main board, then what A of breaker should be in the board, would it be a 63A breaker feeding the 63A Isolator and then down to the distribution unit?

Also any idea what mm2 of cable i should use to run the cable down in?

Thanks for the help chaps

 

[flukey]

Guys, correct me if I'm wrong, you will also need to provide a separate earth for the garage/outbuilding CU & not take it from the main CU.

Alan...

only if there is extraneous conductive parts in the outbuilding

 

[kung]

Just to add if unless the swa is continuous in its length from main cu to outbuilding cu and not run from house cu in pvc to junction and terminated inside into the swa to say run underground or clipped etc outside then the distribution cable needs to be rcd protected.
With regards cable mm2 what length of run is it ? whats the max demand etc etc breaker/cable size etc is same old calcs as for all circuits.

 

[sparks1234]

You should also consider the length or run, if it is excessive then maybe you should consider a TT system

 

[electricAl]

Equinox, it would be useful to all if you could supply more details - cable run lengths, likely loading & especially earthing system, as the exact type would impact on what you need to do (TN-C-S & exporting equipotential zone etc)

As for RCD protection, for many installs outside it isn`t a strict requirement, but i would consider it preferable in most cases regardless. Especially if ponds feature in the install. You mention a CU in outbuilding...can we assume that`ll be feeding s/o cct? If so, 30mA RCD will be required irrespective of cable types.

Also, if an RCD is required, discrimination between the devices needs to be achieved. You don`t say if the `spare` breaker is on the unprotected side of board (assuming split board?)

& to be sure you know, as this is a Special Location it`s notifiable under Part P