07-03-2015, 01:25 PM
Hi Andy,
A can of worms there
I looked into this a few years back. The short answer is that officially, providing a supply to a shed is notifiable work under Part P.
However, what you propose is essentially "running an extension cable". So as it's not a permanent installation, you might be able to argue that it doesn't need notification?
In short, Part P is a mess. You only have to look at the discussions on the various electrical forums to see how confused the professionals are - even on the IET forums - so what chance do we stand? The regulations get revised frequently as well, so it's really hard for us to keep up to date.
There are two main issues from my point of view. First, safety - needless to say. Second, what happens when you need to move house?
It seems that since the recession started all those years back, the whole business of moving house has got more complicated, expensive and litigious. So depending on your long-terms plans, you might want to keep half an eye on that. In your case, the shed might have rotted away before you plan to sell up? Or you might take the shed with you? Either way, if you simply unplug your shed from your external socket, then that might be enough to solve the problem from the legal point of view. Of course, the outside socket might need looking at to ensure it complies with the rules applicable at the time of installation. From what I've read, I think that today, a "new circuit" needs notification - and anything downstream of a protective device is classed as a "new circuit".
Back to safety.
I think it's good that the supply is RCD protected at the house. You're using an RCD plug-top, but are the sockets RCD-protected as well? If so, you might suffer the mild inconvenience of the RCD in the CU tripping first. However, you might want to consider fitting an emergency light fitting out there, as obviously you'll lose lights when the RCD trips. I bought an LED one from CPC for about a tenner recently, and that seems really quite reasonable for the money.
Once the cable is outside, there are lots of rules that ought to apply to it. Again, you could argue that it's no different to running out an extension lead temporarily, but as much as you regard this as "temporary" in the eyes of the law, it will still pay to think about safety - so protection from physical damage is obvious. And making sure it's suitable rated in terms of voltage drop, etc, needless to say. In theory, it ought to be SWA, but that doesn't fit in a 13A BS1363 plug-top especially easily
What about the earth? This is a really complex topic, that starts with determining how your house is fed (PME, TNC-S, etc). An earth spike might be prudent. If there is any plumbing nearby, perhaps that needs bonding?
Ultimately, it might be worth involving a professional. They will take care of the notification process, which would otherwise cost a few £hundred if you were doing it yourself, and if you find one who is "friendly", they might be happy to let you do the actual work - so in effect you're just paying them to design, inspect, test and certify. In the current climate, there are plenty who are happy to work that way, because they know that otherwise folk will just do the work anyway (perhaps unsafely) and not have it inspected, so at least they know that the work is being done properly, and they get something out of the bargain. It's a pragmatic compromise
I never did build the shed, but I need to revisit this because I really need to sort out the feed to my garage. It's just a 4mm T&E that runs the length of the garden with no physical protection whatsoever, and it's simply picked up from behind a socket in the kitchen. Really nasty. That said, we've been here for 10 years, and it hasn't caused a problem. I plan to run SWA of decent CSA because I want to run woodworking machinery out there. But so many other jobs need to be finished first.
Jeffrey (pppenguin) is more up to date with wiring regs than I am, so will hopefully have some more specific thoughts...
Hope this helps,
Mark
A can of worms there
I looked into this a few years back. The short answer is that officially, providing a supply to a shed is notifiable work under Part P.
However, what you propose is essentially "running an extension cable". So as it's not a permanent installation, you might be able to argue that it doesn't need notification?
In short, Part P is a mess. You only have to look at the discussions on the various electrical forums to see how confused the professionals are - even on the IET forums - so what chance do we stand? The regulations get revised frequently as well, so it's really hard for us to keep up to date.
There are two main issues from my point of view. First, safety - needless to say. Second, what happens when you need to move house?
It seems that since the recession started all those years back, the whole business of moving house has got more complicated, expensive and litigious. So depending on your long-terms plans, you might want to keep half an eye on that. In your case, the shed might have rotted away before you plan to sell up? Or you might take the shed with you? Either way, if you simply unplug your shed from your external socket, then that might be enough to solve the problem from the legal point of view. Of course, the outside socket might need looking at to ensure it complies with the rules applicable at the time of installation. From what I've read, I think that today, a "new circuit" needs notification - and anything downstream of a protective device is classed as a "new circuit".
Back to safety.
I think it's good that the supply is RCD protected at the house. You're using an RCD plug-top, but are the sockets RCD-protected as well? If so, you might suffer the mild inconvenience of the RCD in the CU tripping first. However, you might want to consider fitting an emergency light fitting out there, as obviously you'll lose lights when the RCD trips. I bought an LED one from CPC for about a tenner recently, and that seems really quite reasonable for the money.
Once the cable is outside, there are lots of rules that ought to apply to it. Again, you could argue that it's no different to running out an extension lead temporarily, but as much as you regard this as "temporary" in the eyes of the law, it will still pay to think about safety - so protection from physical damage is obvious. And making sure it's suitable rated in terms of voltage drop, etc, needless to say. In theory, it ought to be SWA, but that doesn't fit in a 13A BS1363 plug-top especially easily
What about the earth? This is a really complex topic, that starts with determining how your house is fed (PME, TNC-S, etc). An earth spike might be prudent. If there is any plumbing nearby, perhaps that needs bonding?
Ultimately, it might be worth involving a professional. They will take care of the notification process, which would otherwise cost a few £hundred if you were doing it yourself, and if you find one who is "friendly", they might be happy to let you do the actual work - so in effect you're just paying them to design, inspect, test and certify. In the current climate, there are plenty who are happy to work that way, because they know that otherwise folk will just do the work anyway (perhaps unsafely) and not have it inspected, so at least they know that the work is being done properly, and they get something out of the bargain. It's a pragmatic compromise
I never did build the shed, but I need to revisit this because I really need to sort out the feed to my garage. It's just a 4mm T&E that runs the length of the garden with no physical protection whatsoever, and it's simply picked up from behind a socket in the kitchen. Really nasty. That said, we've been here for 10 years, and it hasn't caused a problem. I plan to run SWA of decent CSA because I want to run woodworking machinery out there. But so many other jobs need to be finished first.
Jeffrey (pppenguin) is more up to date with wiring regs than I am, so will hopefully have some more specific thoughts...
Hope this helps,
Mark
