Help - Advice on wiring for garden office

[Gerardb]

Hi

I hope someone can help.

I have been given planning permission to erect a wooden garden office in my garden on the foundations of my old garage.

Once erected the first job will be to install the electrics. I had planned to do this myself, but are not if I am now able to do that legally under the new regulations.

My plan was/is as follows:

The garden office will be 1m from the back of our kitchen. The kitchen has its own 32a ring main with 5 double sockets powering the following regularly used:

1 * 500mm Fridge
1 * 500mm Freezer
1 * kettle
1 * 500mm dishwasher
1 * Gas heating control system

I assume that this level of load is small compared to the ring main capacity. I can access the ring and it was my intention to break-in properly extend it out into my garden office by taking it out of the kitchen wall, along the side of the house for 1.5m with the 2.5 T&E in a protected PVC conduit to a 1m pipe buried under garden paving to the garden office.

I then planned to include in the office part of the ring

* Two double sockets for a TV, PC and music centre
* A fused spur to power a 2kv convector heater
*A fused spur for two banks of 3 low voltage lights.
* A RCB protected spur into garden shed next door (both will be butted up to each other and power cable under cover at all times) to power a small pond pump, a UVF filter, 100w ceiling light for the shed, an external security light and a Freezer.

Any comments would be appreciated, in particular:

1. Am I allowed under current regulations to extend the ring out of the kitchen in protected conduit as described or will I need to get an electrician

2. In the case of the shed, would it be better to simply extend the ring to include the shed as well or is the RCB protected spur approach OK?

Whilst I have added spurs in the past, I have never really done any external building wiring and welcome any comments people are kind enough to make.

Thanks

Gerry

 

[rebuke]

You are allowed to do it yourself, but since this work involves extending the ring from your kitchen, and outdoor lighting and power, it is notifiable under Part P. This means you need to notify building control before doing any work, and pay them a notification fee. They will then come in and inspect and test at appropriate points during the work. See the wiki for more info...

I wouldn't run T&E underground, even in conduit. Put in some proper SWA (Steel Wire Armoured) cable.

Also, all new general purpose socket outlets must be RCD protected under the 17th edition, so if your existing kitchen circuit isn't, then you'll either need to put an RCD/RCBO in at your consumer unit, or every socket outlet on the circuit must be an RCD outlet. Also, any cables buried less than 50mm in a wall not in earthed metal conduit (or of a suitable type such as SWA) must be RCD protected - if this is going to be the case you would have to protect at the CU.

Given this, you don't need separate RCD protection on the spur in to the garden shed. Also note that if you do do it as a spur, you need to have a FCU (fused connection unit) before anything on the spur, since otherwise you could potentially draw more than 13A. It would probably be nicer to extend the ring, unless there is a specific reason not to...

 

[flameport]

If the ring circuit in the kitchen is already RCD protected, you do NOT want to be extending this into the office building.
If you do, when the RCD trips, you will have no lighting or power in the office - bad enough in the daytime, but a serious hazard when it is dark.

PVC conduit is no good underground - it provides no impact protection.
You can't use normal T+E in underground conduit either as it is not waterproof. (After a while, the underground conduit will fill with water so the cable will be permanently submerged).

 

[Gerardb]

Hi Rebuke and Flameport

Thank you for your responses. I have decided to engage an electrician to put in a new supply to power a seperate ringmain for the office and the shed.

The job is outside of my comfort zone and competence.

Once again, thank you

GErry

 

[ban-all-sheds]

I'd strongly suggest that the specification be to split the tails and run armoured through a switchfuse to a CU in the office.

You don't say how far it is, so no idea what cable you'd need given voltage-drop considerations, but the cost of cable in relation to the overall cost is small, plus digging trenches is a hassle, so in your place I'd install 10mm² SWA to avoid ever having to do it again if the load grows.

You might want to install the cable before building the shed so that you can come up out of the floor inside it.

 

[Taylortwocities]

BAS is right. They are charlatans.

I had a friend that used them and it took them forever to get the work underway and it is still not properly snagged.

Maybe that's where the 2 years went

 

[martinxxxxxx]

BAS is right. They are charlatans.

I had a friend that used them and it took them forever to get the work underway and it is still not properly snagged.

Maybe that's where the 2 years went

 

[ban-all-sheds]

When the mods removed the spam they also removed my post which pointed out that companies who employ people who think it is OK to lie and cheat and steal from other businesses in order to benefit theirs are clearly to be avoided, for why would you risk doing business with a company whose employees are given to lying, cheating and stealing?