Replacing power to an outbuilding

[Paul_H]

Hi, I'm in a victorian mid-terrace. General wiring seems to have been updated with no "rubber" wires left although a few of the old "bakerlite" type round switches are still here and I'm gradually changing them.

There's a two-floor outbuilding (brick built, used as a garage and previously some sort of office space upstairs in the 1970's perhaps) I have stripped it of all contents including wiring, rusty single CU and fixtures etc.

Power is supplied off the main house upstairs ring main from a junction box under the floorboards using 10mm PVC cable to the outside which is then suspended about 4m above ground, attached to a catinary (twine/rope type!) but it is failing and needs taking down.

Clearly I need to change... Can anyone help with advice on some specific questions? It feels like I've been browsing the net for weeks looking for the facts...

1. Is PVC cable as a replacement, with a properly installed metal cable catinary, unacceptable? Some seem to say it must be armoured cable, some say PVC is ok in this installation.

2. I'm pretty sure this should never have been done as a juncton from the ring main in the house. So I think it has to go back to the main house CU - a distance of about 30-35m total with about 20 being indoors.

3. Am I right thinking that I can't do the work due to part P reg's? Shame if not - I'm pretty confident on installing a few sockets and lights in that building, coming of a small CU inside it.

The idea is to put the tumble dryer in there (2.5KW), a freezer, a PC and an electric heater (3KW max). In addition to about 300W of lighting (there is the garage, a small room and the upstairs space)

4. Presently I have nothing running in there, the cable goes temporarily to a small MK fused spur box, running a small outside light. I think the building needs a small CU with 63A 30mA RCD main breaker, 3 MCBs - Outside light (6A?), inside lighting ring (6A?) and mains ring (40A?) - but I'm not certain I have those fuse sizes right yet.

5. If I can replace with PVC - or if I have to use SWA, would 10mm be sufficient, or do you think I need to go up to 16mm?

Any advice gratefully received!

The more I think about this the more it seems like it's more hassle to do myself and get signed off than to get a sparky in to do the lot (just more £££!)

Paul

 

[Paul_H]

Oh... after all that I forgot to ask something

Does anyone know if there's any problems likely by including a couple of network (Cat5) cables attached to the catinary (next to the PVC or SWA mains cable)?

Don't want to do that if it just causes "noise" and impacts on a good "network"

Thanks

Paul

 

[plugwash]

Power is supplied off the main house upstairs ring main from a junction box under the floorboards using 10mm PVC cable to the outside which is then suspended about 4m above ground, attached to a catinary (twine/rope type!) but it is failing and needs taking down.

sounds like a diy bodge

1. Is PVC cable as a replacement, with a properly installed metal cable catinary, unacceptable? Some seem to say it must be armoured cable, some say PVC is ok in this installation.

best not to use T&E outside as it isn't UV proof, split concentric is a good choice if you can find a local supplier.

2. I'm pretty sure this should never have been done as a juncton from the ring main in the house. So I think it has to go back to the main house CU - a distance of about 30-35m total with about 20 being indoors.

right

3. Am I right thinking that I can't do the work due to part P reg's? Shame if not - I'm pretty confident on installing a few sockets and lights in that building, coming of a small CU inside it.

you can do it but you have to notify building control in advance

The idea is to put the tumble dryer in there (2.5KW), a freezer, a PC and an electric heater (3KW max). In addition to about 300W of lighting (there is the garage, a small room and the upstairs space)

A 40A breaker and 10mm cable should be fine for the run from the house

4. Presently I have nothing running in there, the cable goes temporarily to a small MK fused spur box, running a small outside light. I think the building needs a small CU with 63A 30mA RCD main breaker, 3 MCBs - Outside light (6A?), inside lighting ring (6A?) and mains ring (40A?) - but I'm not certain I have those fuse sizes right yet.

the socket ring should be on a 32A breaker, ideally indoor lights should not be on RCD so i'd advise a unit with a switch incomer then RCBOs for the sockets and external lights.

 

[Paul_H]

Thanks Plug!

I've been in touch with my local council regarding this now and they said:

To comply with the Building Regulations, unless the work is being carried out by a Part P competent electrician, you are required to submit a Building Notice to the authority, together with the appropriate fee,(form BN3). When the work is first fixed an inspection of the wiring will be required by a Building Control officer, on completion an inspection and testing certificate should be provided in accordance with BS7671.

When they say testing certificate should be provided is that something an electrician would come along and do? Would I ask for the NICEIC Domestic Electrical Installation Periodic Inspection Report? Do you think that would that cover it?

I can't see any other form on the web other than an installation certificate but that assumes the electrician has done the install which they would not have done in my case.

Many thanks

Paul

 

[plugwash]

doesn't the installation certificate have seperate boxes for signatures from the designer (you though i'd get the person who is going to be testing it to give it the once over) the installer (you) and the tester (whoever you get to do the testing for you).

 

[Spark123]

The form that Plugwash speaks of is available for printing off here (Page 8 ): http://www.iee.org/Publish/WireRegs/Forms_2004.pdf