Garden office electrics
The electrical specification will play a key roll in the usability of your building as a home office. This article will introduce you to the basic electrical set up and explains what is asked of you, the customer, but we advise you also read our lighting, heating, communications and security guides before deciding on your electrical specification.
Most garden offices come pre-wired as standard
All but the most basic garden office designs come as pre-wired units. After all, a garden office wouldn't be very functional without an electrical supply!
A quality garden office will come pre-wired with lighting and power sockets. You can also choose to incorporate telephone, data and audiovisual cabling.
In most instances, garden office designs are built, and then the modular components are put together on-site. As part of this pre-assembly process, all the cables for the power, light and heat are incorporated within the structure of the building. Then when the building is on-site, the system just needs connecting to the mains supply and testing by a qualified electrician.
A garden offices electrics need to comply with Part P of the Building Regulations
It is a legal requirement that a qualified electrician undertakes any domestic electrical work, and this includes connecting the electrical system of your garden office to your house's mains supply.
Depending on the supplier you choose they may undertake this connection as part of the price and package they offer you. In many cases, though, the connection to the mains supply is a job for you, the client, to organise and pay for. This is because most companies don't send an electrician to site with the installation team.
What's involved in connecting the garden offices electrics to the mains supply?
A garden office is connected to the electrics of the house by a heavy duty armoured cable. This cable needs to be buried underground - approximately 500 - 750mm deep. A hazard tape is buried above it, and then the trench is backfilled with stone, before finally replacing the earth. This is to ensure that the cable is more than a spades depth deep. This ensures that if anyone should dig in the area in the future, they will be warned of a cable by the stone and hazard tape.
Depending on how far your garden office is from the house will affect how long a trench will need to be dug. This is a labour intensive business, and if you want to cut down on costs, maybe a job you could undertake yourself. You would need to speak with the electrician who will advise you on the ideal depth of the trench and the route it should take.
You may well find that some companies will suggest pinning the armoured cable to a wall or fence, rather than burying it in a trench. This will reduce the cost of connecting the electrics to the mains supply, but it is not the recommended method, which is burying the armoured cable in a trench.
Your electrician will connect one end of the armoured cable to the consumer unit in the office and the other end to your main fuse board in the house. The electrician will also add an earth rod to the garden office, this is inserted into the ground near the building and has a green and yellow cable running from it.
Once the office is connected to the mains supply, the electrician will test the circuits. Once everything is complete will issue with a certificate showing that everything has been tested and complies with the Building Regulations. You will want to keep this certificate in a safe place. You will need it when you come to sell your house.
A trench is normally dug to connect the garden offices electrics to the mains supply in your house. This trench is then backfilled and you'd never know it was there in a few weeks time.
A garden offices electrical connection is often a hidden cost
Don't get bitten by the hidden cost of connecting your garden office electrics to the mains supply. Not many garden room companies send a qualified electrician to site as part of the installation team. Instead, they ask you to organise a local electrician to make this final connection once they have completed the building. It is easy to overlook the cost of connecting the electrics, but it is a crucial aspect of making your building functional.
It is difficult to estimate the costs involved as the distance the office is from the house will impact on the amount of armoured cable needed. Also, you may need a new circuit added to your fuse-box depending on your electrical set up. To give you a ballpark estimate we would allow between £1,000 and £1,500 for this job.
What to expect from a standard garden office electrical specification
A lot of thought has been given to the basic electrical specification of garden office designs. Designers have worked out the optimum number of sockets, lights and heating output for the size of the building and these make up the standard electrical pack offered.
It is worth thinking at the design stage if this standard specification is enough for you. Do you need a few extra power sockets for all your gadgets, or do you need to add data cabling to the spec? Adding extra sockets, lights and data cabling is relatively easy and cost-effective at the design stage compared to when the building is finished.
High spec garden office designs are often finished with chrome or brushed steel face plates on the sockets and switches, but unless you see this stated in the specification assume the switches are white plastic - just like those used in a house.
Most garden office designs today have flush, i.e. the face plates are flush with the wall, and the cables are hidden within the structure of the building. But, there are still a few designs on the market that use surface mooted systems which have trunking and the sockets sitting proud on the walls. There are a few companies who use deep trunking systems with the sockets in. Rather like you will see used in a hospital ward. They tend to run this trunking at waist height or at the bottom of the wall instead of a skirting board. This is not the most aesthetically pleasing option but does offer flexibility that you can easily add sockets to the system in the future without damaging the decor.
This article covers the basics of the electrical system of a garden office; we recommend you read our lighting, heating, security and communications guides which are all essential aspects of your electrical specification.