Rewiring Shed

[Big_Spark]

Use a 4-way consumer unit. Have the main incomer as a 30mA RCD.

Works for me.

Why four way...??

 

[Steve]

future expansion. got 2 blanks there at the moment. B32 ring (freezer, radio, lawnmower etc) and B6 lights. Budget didn't allow for customised outraegeous RCD arrangements

 

[securespark]

If your freezer is going to bypass the RCD, it should be wired through a sw/spur or the socket clearly labelled as unsuited for equipment to be used outdoors.

 

[mdbalson]

Use a 4-way consumer unit. Have the main incomer as a 30mA RCD.

Works for me.

The ccu in the house that the shed is fed from has a RCD.

(the ccu that the shed is on has: Shed, Kitchen Ring no. 1 (32amp MCB), Kitchen Ring no. 2 (32amp MCB), Cooker (32amp MCB?))

 

[mdbalson]

http://www.MyOnlineImages.com/Members/mdbalson/images/Both Consumer Units.JPG

Picture of Meter cupboard

The bottom white ccu is the one that the shed is run off from.

The metal app. box on the side of the cupboard is for the shed.

 

[Big_Spark]

future expansion. got 2 blanks there at the moment. B32 ring (freezer, radio, lawnmower etc) and B6 lights. Budget didn't allow for customised outraegeous RCD arrangements

That would not be enough, that was why I questioned it.

The freezer should be on it's own radial.(Non RCD)
External socket on it's own radial (30mA RCD)
External lighting on it's own (30mARCD)
Internal Lights (Non RCD)
Tumble Dryer* (Optional)
Heater*(RCD)

*Personally I would put these on their own circuits, just as easy as wiring a ring and it is likely both could be on simultaneously and without knowing the rating of the heater I would not risk putting them on the same circuit.

The easiest way to achieve this would be a split load board. It is the freezer that presents the problem. These should never really go on an RCD, but if located externally then the supply should be RCD protected for compliance.If the freezer were not located in the shed then wiring everything else would be simpler as the feed already has an RCD at the supply end.

Then to comply with the Regs, ideally you need a couple of spare ways.

 

[mdbalson]

OK..well the shed should be fed with a 6mm² feed to ensure it can handle the potential load with everything you have said.

The Main Incomer should be a 100mA 40A Type S RCD.

I would suggest that each piece of equipment has it's own circuit and that the Pond pump, lawn mower socket and heater are fed on 30mA RCBO's. Whilst this is not a requirement it is advisable as you are having a freezer in there. It is s***s law that one would fail and trip the main RCD just after you leave for holiday!!

I suggest these as these are the most likely to cause nuisance tripping. DO NOT PUT THE FREEZER ON ANYTHING OTHER THAN AN MCB, they have a habit of tripping them, hence using the 100mA main RCD.

Would this be ok if I did this:

The ccu in the house has a 80mA RCD Main Incomer

Put in a 32 amp MCB in the House ccu

Put in a Wylex Metal 5 way Consumer Unit with a 100A Dp Isolator Sw in the shed

Put in a double socket for the Tumble Dryer, and Freezer, which is on its own MCB in the shed ccu

Put the other two double sockets on a Ring Main which is on its own MCB in the shed ccu

Have the pond pump on a RCD FCU which is run off the socket Ring

Put the outside lights on a 6 amp MCB in the shed ccu

Put the shed light on a 6 amp MCB in the shed ccu

Then should I use 4mm swa (as my tutor at college said to) or 6mm SWA, to fed the shed.

(My tutor is an ex elecy, as I am doing the C+G 2330 in electrical Installtion Level 2)

 

[Big_Spark]

mdb, on the whole that is OK, but I would suggest that you use a RCD FCU for the outside lights and the socket that will feed the lawnmower certainly needs 30mA protection. You don't want to be tripping it and forgetting to reset it when you have a freezer on the same supply.

4mm² will proabably be electrically ok, but it may not comply with BS7671. Remeber, if you have the Tumble dryer running (12A) the freezer on (about 5A), the heater running (about 10A) and say the lawnmower going (say 10A) then you have a potential load of 37A, not including your lighting.

I understand that this situation may be rare, so is being shot, but the Police still wear bullet proof vests for a reason!!

I would use 6mm², the cost difference is small, and it will give greater protection if the supply does get loaded up. I would also suggest this be a 3 core SWA so the main earth is integral to the cable.

I assume that you made a typo with the RCD and that it is an 80A 30mA RCD, I don't recall ever coming across a 80mA RCD..

 

[mdbalson]

mdb, on the whole that is OK, but I would suggest that you use a RCD FCU for the outside lights and the socket that will feed the lawnmower certainly needs 30mA protection. You don't want to be tripping it and forgetting to reset it when you have a freezer on the same supply.

4mm² will proabably be electrically ok, but it may not comply with BS7671. Remeber, if you have the Tumble dryer running (12A) the freezer on (about 5A), the heater running (about 10A) and say the lawnmower going (say 10A) then you have a potential load of 37A, not including your lighting.

I understand that this situation may be rare, so is being shot, but the Police still wear bullet proof vests for a reason!!

I would use 6mm², the cost difference is small, and it will give greater protection if the supply does get loaded up. I would also suggest this be a 3 core SWA so the main earth is integral to the cable.

I assume that you made a typo with the RCD and that it is an 80A 30mA RCD, I don't recall ever coming across a 80mA RCD..

Yes the RCD is probably a 80A 30mA one.

I was going to use 3 core SWA, and use one of the cores as the earth, and I was also going to earth the steel armor as well.

I was also going to run the cables for the sockets and lights, in 20mm PVC Round Conduit.

What if I :

Have a RCD FCU for the outside lights and the floodlight, as well as a RCD FCU for the pond pump.

Put a RCD Plug onto the Lawn mower.

So would this be alright?

So I should use 6mm SWA then, and would a 32 amp MCB in the House ccu, for the shed be ok?

 

[mdbalson]

I have just checked and Yes the RCD is a 80A 30mA one.

Would what I said in the reply above be alright

 

[mdbalson]

So would this be an ok, the way I was going to do it

Should I use 4mm Or 6mm SWA

Would a 32amp MCB in the house ccu be ok for the shed

Thanks

 

[mdbalson]

The way I am going to do it now is:

Put in a 32 amp MCB in the House ccu

Change the 2.5mm T+E to 6mm T+E, which runs from the ccu to the Metal app. box

Change the 2.5mm SWA to 6mm SWA, which runs from the Metal app. box in the House to the Shed ccu

Change the old Wylex Metal 2 way ccu (Rewireable Fuses), to in a New Wylex Metal 5 way Consumer Unit with a 100A Dp Isolator Sw (MCBs), in the shed

Put in a double socket for the Tumble Dryer, and Freezer, which will be on a Radial, on its own MCB in the shed ccu (16 amp or less)

Put in three double sockets along the worktop, which will be on a Ring Main, on its own 32amp MCB in the shed ccu (as well as the Pond Pump)

Have the pond pump on a RCD FCU which is run off the Socket Ring

Put the outside lights on a RCD FCU on a 6 amp MCB in the shed ccu

Put the shed light on a 6 amp MCB in the shed ccu

Plug the 2kW Heater into one of the Ring Main Sockets.

Run the Cables in the Shed in Round Platic Conduit.

Clip up the SWA with cable cleats


So would this be ok

 

[mdbalson]

So would the way I was going do the wiring, be ok

 

[miajanjua]

Need some information.

TOTAL distance from House CCU to Shed CCU..

Total expected load in the shed...

What type of ingress protection does the shed have?

Total distance from House CCU to Shed CCU is about 5m or less.

Load in the Shed will be:

Freezer = 500w

Tumble Dyer = 3Kw

Heater 2Kw

Outside Floodlight =500w

Pond Pump =100w

Two sets of Low Voltage outside lights =200

Lawn mower =1Kw

A total possible load of 7500watts.

A possible total run of 10m to the loads.

4mm2 SWA will have Volt Drop of 5.57V, well within 9.2v

Total current is 32.6A @ 7.5Kw, max rating of 4mm2 SWA is 41A.

I would install 3core 4mm2 SWA( Phase+Neutral+1 for earth).

install a 4-6way split CU in the shed fed by a 32/40A breaker from non-RCD
side of the main CU with circuits for
1) Lights
2) Freezer( Hard wired though a FCU )
3) Socket ring circuit on 30mA RCD for tumble dryer,heater,lawnmower etc
4) Pond Pump on 30ma rcd

 

[mdbalson]

The Run of SWA is about 13m from the house ccu to the shed ccu