Outdoor Electrics

[jamie.aston]

Hello All,

I am in the middle of re-vamping my garden and will need to supply power to 2 Sheds and a large decked area. Due to the age of my Distro Panel in the house i will also be replacing with a new Consumer Unit. I plan on doing this as below. I have re-wired a house before and had signed off by an electrician (said i'd done a good job and to a very high standard) but not too sure with this one:

House
10 Way Split Board
3 x 6 A Radial Lights (3 Floors)
80A 30mA RCD
1 x 40 A Spur (Shower)
3 x 32 A Ring Mains (3 Floors)
1 x 63A 30mA RCD to Utility Shed Via 10mm SWA 2 Core (Use Galv as Earth)

Utility Shed
4 Way CU
60A Isolation Switch
1 x 6A Lighting Circuit
1 x 20A 30mA Socket Circuit (Runs FridgeFreezer)
1 x 63A 30mA RCD to Decked Area Via 10mm SWA 2 Core (Use Galv as Earth)

Decked Area
8 Way Weatherproof CU
60A Isolation Switch
1 x 6A Lighting Circuit (2 x 12v Transformers with LV Lights)
1 x 20A 30mA RCD for Hot Tub Connection (16 amp Hot Tub)
1 x 20A 30mA RCD Socket Circuit
1 x 20A 30mA RCD Electric Heater Circuit
1 x 40A 30mA RCD to Tool Shed Via 6mm SWA 2 Core (Use Galv as Earth)

Tool Shed
2 Way CU
40 A Isolation Switch
1 x 6A Lighting
1 x 20A Socket

2.5mm T&E - All Sockets & Spurs
1.0mm T&E - All Lighting

I have a 60A fuse next to my Electric Meter & Electricity through overhead cabling (doesn't look that beefy), will i need to get electricity board in to change anything?

Any comments welcome.

Thanks In Advance
Jamie

 

[Steve]

OK, first things first, use 3 core SWA. Amour connections can deteriorate without anyone noticing. And I'm not sure if 10mm 2 core's armour is acceptable for an earth conductor.

Its not nessecary to use more than one RCD of the same trip rating protecting the same circuit. So less of the RCD mania.

At the house everything sounds ok. But consider having the shed submain on the non-RCD side. Local RCD protection is always better, and ONLY sockets which could reasonably be expected to supply electricity to outdoor appliances need be RCD protected. Showers and hot tubs should also be RCD protected.

Not many domestic boards are designed for a 63A MCB. And the shower circuit isn't a spur, its a radial.

What's the wiring distance from house to shed, shed to deck, deck to toolshed? This will have an effect on circuit design.

In the utility shed, dont RCD protect the fridge-freezer. Use a fused flex outlet for it. If you need a socket outlet there for other things, use an integral RCD protected socket, off the fridge freezer circuit.

Again, dont RCD protect the decked area at the submain source. I'm not keen on the idea of an 8-way weatherproof CU. Could this not be housed in either the shed of the toolshed? For a start, where will you put the transformers?

Electric heater circuit? Outdoors? Please dont! Total waste of money. And gas is much more efficient.

Note that all outdoors circuits need to be in an appropriate cable.

You seem to have the right idea, but it needs a lot of refining! Try again, and take what i've said into account. Go through the exact protective devices that you'd use for each circuits in each board.

PS. when you mention all those RCDs in the outdoors CU, what do you mean? an actual 2-pole RCD or an RCBO? An RCBO is an MCB and RCD in a single 1-wide module. I suggest you take advantage of these. Very neat

 

[JohnD]

An RCBO is an MCB and RCD in a single 1-wide module. I suggest you take advantage of these. Very neat

Great idea

 

[Steve]

Thought you'd like that John!

 

[jamie.aston]

Crafty, thanks for the reply. How is this?

House
10 Way Split Board
3 x 6 A Radial Lights (3 Floors)
1 x 63 A MCB to Utility Shed Via 10mm SWA 2 Core (15m)
80A 30mA RCD
1 x 40 A Radial (Shower)
3 x 32 A Ring Mains (3 Floors)


Utility Shed
4 Way CU (6mm to Earth Spike)
60A Isolation Switch
1 x 6A MCB Lighting Circuit
1 x 20A MCB Socket Circuit (Runs FridgeFreezer)
1 x 60A MCB to Decked Area Via 10mm SWA 2 Core (10m)

Decked Area
8 Way Weatherproof CU (6mm to Earth Spike)
60A Isolation Switch
1 x 6A MCB Lighting Circuit (2 x 12v Transformers with LV Lights)
1 x 20A 30mA RCBO for Hot Tub Connection (16 amp Hot Tub)
1 x 20A 30mA RCBO Socket Circuit
1 x 20A 30mA RCBO Electric Heater Circuit (Outdoor Heater=http://www.tlc-direct.co.uk/Products/TLOH1300B.html)
1 x 40A MCB to Tool Shed Via 6mm SWA 2 Core (10m)

Tool Shed
2 Way CU (6mm to Earth Spike)
40 A 30mA RCB
1 x 6A Lighting
1 x 20A Socket

2.5mm T&E - All Sockets & Spurs Indoor
1.0mm T&E - All Lighting Indoor
2.5mm 3 Core SWA - Outdoor Sockets
1.0mm 3 Core SWA - Outdoor Lighting

I have a 60A fuse next to my Electric Meter & Electricity through overhead cabling (doesn't look that beefy), will i need to get electricity board in to change anything?

Any comments welcome.

Thanks In Advance
Jamie

 

[Steve]

That looks much better. Though where you need the 3 RCD circuits outdoors, it might be better to use a split load board due to cost of the RCBOs.

Another issue just ocurred to me - what earth system do you have currently? multiple earth rods aren't normally nessecary.

Did you consider my comment on moving the outdoor CU indoors?

 

[jamie.aston]

Thanks Again Crafty.

Looked at moving the board inside but SWA Cable would cost me a small fortune (10m x 10mm vs 30m x 2.5mm & 10m x 1mm & 25m x 6mm).

Not really sure how i am earthed ATM, will be ripping the cupboard from around my current distro board tonight.

Multi Earth rods (one at each location) will enable me to use 2 core 10mm cable and still be safe (my thinking anyway, could be wrong)

Will add 60A RCD to Outdoor CU and use MCBs on each circuit (MK RCBO's are REALLY EXPENSIVE).

Any comments on the cable supplying my property anyone?

P.S. Signed up for my C&G Technical Certificate Levels 1 in Electrical / Electronic Competences last week . Find this stuff really interesting, beats IT Project Mgmt hands down!

Thanks
Jamie

 

[Deleted member 54734]

Contact you supplier about getting somebody out to look at the incoming cable to your property.

But if their anything like the supplier I work for they won't touch it unless it's realy bad.

Always worth getting somebody out to check tho.

 

[Steve]

Contact you supplier about getting somebody out to look at the incoming cable to your property.

But if their anything like the supplier I work for they won't touch it unless it's realy bad.

Always worth getting somebody out to check tho.

Why? He never said his incoming supply cable was an issue. The mainfuse is a little undersized, but this isn't normally an issue (though it could be a 60 amp holder with a 40 amp fitted). If it ever blows (highly unlikely), the DNO will be out within a few hours to change it anyway.

 

[JohnD]

overhead cables are well ventilated so seldom overheat.

He will probably be on a programme (if they are very old) to replace overheads with fully insulated cable in the fullness of time (network owners seem to be doing that), and I expect that will be in a thicker cable if the old ones are very thin.

 

[Steve]

Yeah, our 5-wire bare overhead runs were replaced a few years ago. Now run underground, as I guess a 4 core SWA is a bit chunky to run overhead

 

[Deleted member 54734]

Any comments on the cable supplying my property anyone?

Sorry must have misunderstood?

 

[JohnD]

Why? He never said his incoming supply cable was an issue. .

The boy's a little overexcited, please excuse him

 

[Deleted member 54734]

LOL just read the thread 10times trying to work out what it was then.
np's lol

 

[equitum]

Looked at moving the board inside but SWA Cable would cost me a small fortune (10m x 10mm vs 30m x 2.5mm & 10m x 1mm & 25m x 6mm).

Is it necessary to use SWA under the decking - rubber flex instead? How are you switching the lights, at the CU or with IP rated switches on wall etc ? And where are the transformers going, can these be put in IP rated boxes under the decking (with access panel built into decking)?

Asking these questions as have similar decking project