UK Power to Shed

[Bathey]

Hi All I’m new to the forum thing so go easy on me ;-)

if I am planning on putting a garage unit into my shed which will have a 32amp for power and 6amp for lighting is that OK to be fed from a 40amp breaker from the main board in the house ?

I didn’t know because of discrimination if I could just put the garage unit on an MCB ( which is in an RCB with one half of the circuits from house ) or if the shed circuit ( distribution circuit) would need to be on a Separate RCB/RCBO.

I know if there is a fault in the shed then the shed RCD would trip but if there was a fault between the shed and the main CU it would trip the house RCD.

If the Shed has to be on an Separate RCD then that would mean using an RCBO and since it just an RCD board I would need to replace the house board to be an RCBO board.

hope that all makes sense. Hope someone can shed some light on this.

 

[Pete999]

Hi All I’m new to the forum thing so go easy on me ;-)

if I am planning on putting a garage unit into my shed which will have a 32amp for power and 6amp for lighting is that OK to be fed from a 40amp breaker from the main board in the house ?

I didn’t know because of discrimination if I could just put the garage unit on an MCB ( which is in an RCB with one half of the circuits from house ) or if the shed circuit ( distribution circuit) would need to be on a Separate RCB/RCBO.

I know if there is a fault in the shed then the shed RCD would trip but if there was a fault between the shed and the main CU it would trip the house RCD.

If the Shed has to be on an Separate RCD then that would mean using an RCBO and since it just an RCD board I would need to replace the house board to be an RCBO board.

hope that all makes sense. Hope someone can shed some light on this.

2 RCDs on the same leg is not a good idea, this is a private job other than your full time employment I have assumed???

 

[Bathey]

Yes a private one

 

[buzzlightyear]

Yes a private one

Is this job op, are you work for a company or your self ?

 

[davesparks]

I know if there is a fault in the shed then the shed RCD would trip but if there was a fault between the shed and the main CU it would trip the house RCD.

A fault in the shed will trip the RCD in the house if it is connected to it, the RCD in the shed will also probably trip.

 

[MJPD29]

Don't put RCDs in series. What size/type of cable are you using?

 

[DPG]

Could you get a SWA to the shed? Are you able to calculate the appropriate size?

 

[Bathey]

Is this job op, are you work for a company or your self ?

im just starting out this job will just be for my dad
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Could you get a SWA to the shed? Are you able to calculate the appropriate size?

It’s for my dad and he already has 16mm2 , this is overkill but might as well over egg it than under egg it.
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Don't put RCDs in series. What size/type of cable are you using?

SWA 16mm2

 

[telectrix]

you could split the tails in the huse with henleys an fit a switch fuse (63A?) to feed the SWA.

 

[Snailspark]

if there is room on the fuseboard, you could add an MCB between the main switch and the RCD to feed the shed. 32A would be fine.
then into the shed fuseboard which would have it’s own RCD feeding the sockets and lights.
should a fault occurs the shed, it will trip the shed rcd, not the main house one and visa versa...

 

[Bathey]

if there is room on the fuseboard, you could add an MCB between the main switch and the RCD to feed the shed. 32A would be fine.
then into the shed fuseboard which would have it’s own RCD feeding the sockets and lights.
should a fault occurs the shed, it will trip the shed rcd, not the main house one and visa versa...

Great thanks this is helpful and think it is the way I will do it. We have enough SWA to go from the utility to the shed but not the main board so would the follow be OK.

1. A 16mm2 T +E from a MCB at the main board( not RCD protected ) the 16mm2 T+ E will then go through the house to the Utility.

2. 16mm2 T+E will then be joined inside the house utility to a SWA 16mm2 up to the shed. It will be joined via A separate main switch with will be on the wall inside.

3. Once joined the SWA will lead to the shed board which will be RCD protected.

I no ideally you would have an SWA from the shed to the main board but we already have the cable so will joining it via a separate main switch at the back of the house utility be acceptable ?

 

[DPG]

Will the 16mm T&E be surface run all the way?

 

[Bathey]

Will the 16mm T&E be surface run all the way?

no it’s not surface run it runs from the board to the utility under the floor. Is that OK ?

 

[DPG]

no it’s not surface run it runs from the board to the utility under the floor. Is that OK ?

But does it meet the requirements for not having RCD protection?

 

[Bathey]

But does it meet the requirements for not having RCD protection?

Yes - Apart from the fact it would be connected to the SWA which does run outside ( which when a cable is used in the garden it would be require an RCD) but then again the termination won’t be outside as it would terminate in a shed.

otherwise I guess it would be better to run the cable from RCD protected inside and have no RCD in the Shed ?

 

[DPG]

Yes - Apart from the fact it would be connected to the SWA which does run outside ( which when a cable is used in the garden it would be require an RCD) but then again the termination won’t be outside as it would terminate in a shed.

otherwise I guess it would be better to run the cable from RCD protected inside and have no RCD in the Shed ?

I'm not sure you've fully grasped the requirements for RCD protection.

 

[Bathey]

I'm not sure you've fully grasped the requirements for RCD protection.

cable is in safe zone in the house and it doesn’t run through a bathroom nor does it supply sockets of 20a. Is that what your talking about ?

 

[DPG]

I was meaning the 'less than 50mm depth ' rule.

 

[Bathey]

I was meaning the 'less than 50mm depth ' rule.

95% of the cable runs through the floor not in the walls so the 5% that does run down the wall to the where it joins the swa via a separate main switch , I will make sure either it is 50mm back in the wall or it has mechanical protection. Apart from that I think it’s fine yeah ?

 

[davesparks]

1. A 16mm2 T +E from a MCB at the main board( not RCD protected ) the 16mm2 T+ E will then go through the house to the Utility.

2. 16mm2 T+E will then be joined inside the house utility to a SWA 16mm2 up to the shed. It will be joined via A separate main switch with will be on the wall inside.

Why on earth do you want to join it using a switch?

And why extend it with T&E?
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95% of the cable runs through the floor not in the walls so the 5% that does run down the wall to the where it joins the swa via a separate main switch , I will make sure either it is 50mm back in the wall or it has mechanical protection. Apart from that I think it’s fine yeah ?

What is the wall made of? If it's a solid wall how are you going to cut a deep enough chase without damaging the structural integrity of the wall?