Unable to bury SWA

[maguire]

Hi, am running power to shed about 20 mtrs from the back of the house .i know this is notifiable but I need advise in adhering to the regs in regards to running swa this distance ( 2.5m t&e from main consumer unit, outside to weather proof junction , will then run swa from there to shed where there is a two way cu with 16amp and 6 amp rcbos, main cu in house has ' all unit RCCB' protection. This power is just for two sockets and a light)The garden is tiered and all concrete, no earth to dig and bury the cable in. The boundary walls and fences are only 2 metres high, does anyone have any suggestions as to the best way to run the swa, keeping in line with any necessary regs. Is it feasible to just cleat it to the walls and run along there, would it need to be encased in any trunking etc?Help appreciated

 

[malcolmsanford]

Welcome to the Forum

Yes it is possible and within the regulations to cleat the SWA to a wall. Though you have to assess what are the chances of

a) If it is wooden of the fence rotting and then collapsing hence damaging the cable
b) Even if Brick is it your fence or a neighbours and will they want to remove it.

Now you have mentioned notifying which you are correct in assuming if you are in England & Wales

I would though be thinking more of

a) Why are you fitting a 2 way RCBO CU in the shed when your house CU already have them
b) By keeping the RCBO protection in your house, chances are on a fault situation both RCBOs will trip leaving you in the pitch black in mid winter and Mrs Maguire royally peed off if she is watching Eastenders
c) Are you sure that 1.5mm Earth/CPC in that Twin and Earth is man enough for this sub main

And the list goes on, what earth system are you on, how are you going to test this circuit, how will you be issuing certification for the circuit

 

[Brightspark2]

You could cleat it along...

You won't have any discrimination there with the RCCB in the house and the RCBO's in the garage...

Sent from my Xperia S using next doors WIFI

 

[Brightspark2]

Can't edit on phone but no need for trunking with SWA, just run it along...

Sent from my Xperia S using next doors WIFI

 

[Octopus]

Discuss the options with the client - sometimes laying the SWA on the surface is the only way...

 

[maguire]

Thank you for all your comments. I'll actually be using 2.5mm T&E, this should be sufficient as power use in the shed is just for things like kettle, stereo etc , no power tools etc.
i was using RCBOs in the shed CU to provide overcurrent and short circuit protection as the RCCB protecting the whole origin CU doesn't offer that. Do you feel this is unnecessary then and OTT?

 

[Octopus]

Thank you for all your comments. I'll actually be using 2.5mm T&E, this should be sufficient as power use in the shed is just for things like kettle, stereo etc , no power tools etc.
i was using RCBOs in the shed CU to provide overcurrent and short circuit protection as the RCCB protecting the whole origin CU doesn't offer that. Do you feel this is unnecessary then and OTT?

Outside??

 

[Brightspark2]

Thank you for all your comments. I'll actually be using 2.5mm T&E, this should be sufficient as power use in the shed is just for things like kettle, stereo etc , no power tools etc.
i was using RCBOs in the shed CU to provide overcurrent and short circuit protection as the RCCB protecting the whole origin CU doesn't offer that. Do you feel this is unnecessary then and OTT?

The RCCB and RCBO both provide earth fault protection but there's no discrimination with them, which ever is the quickest to react will trip first. You only need MCB's in the garage CU.

T+E installed as you describe is a concern, I'd recommend you use SWA.

Sent from my Xperia S using next doors WIFI

 

[maguire]

Hi EXperia thanks for your comments. I will be using T&E from the main CU in the house to the exterior wall where it will be connected in a weatherproof box to the SWA I intend to run in the garden to the shed, was just unsure before all your comments if the SWA could be run overground if unable to bury it. Seems it can, so let work begin! Thank you

 

[gonefishing]

Hasn't anyone heard that RCD's RCCB's don't work in parallell, you should have only 1 RCd or whatever on any circuit, so put 1 in the board or use an RCBO for the circuit or even use a stand alone box dedicated for the exterior supply if there's no extra ways available. The disconnector device must be at the ORIGIN of the circuit to protect the cable and also taking into account any other factors. Putting a RCD at the end of a circuit will not protect the cable or any person who is exposed to a fault condition. As for fixing an SWA if it's not buried ....properly ..... the regs are clear here don't try and hide it use a catenery cable if you need to. Just make sure the SWA is terminated correctly !! I think the NICEIC view is still if it's correctly installed to a solid structure .. fence etc and visible it's good but beware of fixing to a fence.... the next door neighbour may own the fence ! and may decide to Cresote it or even remove it.

 

[Brightspark2]

Hasn't anyone heard that RCD's RCCB's don't work in parallell,

They do...


The quickest to react will trip first...

 

[maguire]

Hi gone fishing thanks for your comments. The whole consumer unit at origin has an RCCB as main switch, thus protecting all the ways in that unit, including the one spare one I shall be using to feed the outside supply. So this RCCB should be sufficient to act if there was any fault in the circuit including the swa line towards the shed? I can't get an RCBO on the non RCD/RCCB side as the RCCB is The main switch protecting the whole board.

 

[MDJ]

Just my opinion fella, however I would never consider a 2.5mm2 armoured cable to a shed, even if you connect it to a 16 amp fuse and protect it via a RCD or a combined RCBO, I would suggest a 6mm2 at least, you need to consider abiatic equation regarding circuits under fault conditions, and remember the RCD could fail, if so you would need the breaker to deal with the fault, a 20 mtr run to a shed with a potential 16 amp supply may need a bigger cpc than a sheath or a 2.5mm2 conductor if you use a 3 core of course, and lets not forget temperature problems, JMO.

Kind Regards

Mike

 

[Octopus]

Just my opinion fella, however I would never consider a 2.5mm2 armoured cable to a shed, even if you connect it to a 16 amp fuse and protect it via a RCD or a combined RCBO, I would suggest a 6mm2 at least, you need to consider abiatic equation regarding circuits under fault conditions, and remember the RCD could fail, if so you would need the breaker to deal with the fault, a 20 mtr run to a shed with a potential 16 amp supply may need a bigger cpc than a sheath or a 2.5mm2 conductor if you use a 3 core of course, and lets not forget temperature problems, JMO.

Kind Regards

Mike

2 core SWA shouldn't be used in domestic situations for the very reason you outline. I always use 3 core SWA.

 

[HandySparks]

Just my opinion fella, however I would never consider a 2.5mm2 armoured cable to a shed, even if you connect it to a 16 amp fuse and protect it via a RCD or a combined RCBO, I would suggest a 6mm2 at least, you need to consider abiatic equation regarding circuits under fault conditions, and remember the RCD could fail, if so you would need the breaker to deal with the fault, a 20 mtr run to a shed with a potential 16 amp supply may need a bigger cpc than a sheath or a 2.5mm2 conductor if you use a 3 core of course, and lets not forget temperature problems, JMO.

Kind Regards

Mike

Hi Mike,
I may be missing something here, but could you give an example of a case where 20m of three core 2.5mm² SWA cable (using one core as the CPC) protected by a 16A fuse or MCB would not meet the regulations. I can't think of one myself.