Replacing supply to garage

[PJGWiltshire]

Hi there.
I am not an electrician and ask this question of your forum.
My house needs rewiring as the cables although not perished are the type fitted in the 1960s and the lighting circuit is not earthed. The house CU is around 20 years old(Professionally installed) and the house is protected by a RCD between the Meter and CU, so if it trips the whole house supply is shut off.
I have lived in the house for over 35 years and one of the first jobs I undertook when moving in was to run a supply to a detached garage for a light and a double socket.
At the time I ran the supply cable in 2.5M twin and earth and to reach the garage it was buried in steel conduit.
Well time has moved on and having read all about Part P and the like I am aware of the need to have a qualified electrician carry out CU work and new circuits.
As mentioned it is my intention to have the house rewired late this year which will include work within the garage.
My issue is around some work I am having carried out on the garden which will result in digging up the area near the garage.This will enable me to replace the old supply cable with 6mm 3 core SWA.
Obviously I would like to connect this cable to the small junction box I have in the garage and the other end to the CU.
In the garage, from the junction box I installed a 6A fuse switch for the light feed, the double socket sits protected by the house CU trip switch which is 16A.
I appreciate a new CU will have the built in RCDs when replaced along with a CU in the garage
In preparation for the amount of work I will undertake in the house renovation I am looking to instal another twin socket for tool charging and running small power tools from the socket (chop saw)
The question I ask is am I allowed to instal the SWA myself and not breach the Part P regulations and not need a certificate.
I will be earthing the SWA at the house CU both from the core cable and the SWA outer covering.
Many thanks in anticipation for any advice.

 

[davesparks]

You need to inspect, test and certify in accordance with the wiring regulations regardless of whether part P notification is required or not.

Inspection and testing is an essential part of compliance with the wiring regulations and without carrying it out correctly you could be left with a dangerous installation.

 

[Pete999]

PG can I suggest in order to do the job you require safely you employ the services of an Electrician, it will be safer and more benificial for you in the long run.
I'm all for saving money where possible , but in this case, you need proffesional help, and good luck.

 

[Rpa07]

If you intend a full rewire later in the year then carry on with the 2.5 which exists and when you hire the electrician to rewire, work with him/her to dig and install the calculated cable. They will have seen 1st fix and second and test it to add to your certificate of electrical loveliness and notify.
Ps that is possibly the nicest avatar I’ve seen in a long time and not a pet in sight, except for the chick of course!

 

[Octopus]

The ideal solution for a new cable to the garage is directly from the house CU to the new garage CU....... avoiding ALL unnecessary joints

As for fuseboards - save up a little extra and have a RCBO board fitted.

My advice to you is to get a spark engaged, sooner rather than later...

 

[PJGWiltshire]

Many thanks for the quick responses. OK shall get someone to carry out all the fix at rewire have .
As the dig is taking place from tomorrow it is sensible to lay the SWA and then back fill ready for electrician to connect up in due course. ( having the patio and drive block paved) do not want to dig this up later
From some of the answers am I understanding that the electrician would need to lay the SWA or would they just see that its installed. I am digging down .75m to lay will sand and cover with cable notice.

 

[Octopus]

maybe you should consider simply burying ducting (with a rope or pull cord)

 

[PJGWiltshire]

maybe you should consider simply burying ducting (with a rope or pull cord)

Good idea!!!, last question, is there any specific regulated ducting or anything suitable that the SWA can get through

 

[telectrix]

any sensible plastic tube will suffice. for a 6.0mm SWA cable, something with an internal diameter of 1" is fine, but no sharp bends.

 

[Octopus]

take your pick:

Twin Walled Cable Duct - https://www.tlc-direct.co.uk/Main_Index/Cable_Index/Cable_Ducting/index.html

 

[PJGWiltshire]

take your pick:

Twin Walled Cable Duct - https://www.tlc-direct.co.uk/Main_Index/Cable_Index/Cable_Ducting/index.html

Will be out first thing to get some

 

[Spoon]

The ducting is a good idea as if you require any additional cables, like phone, ethernet or alarm cables, then these can be put in as well at any time. Just leave a pull core in.

 

[Risteard]

The ducting is a good idea as if you require any additional cables, like phone, ethernet or alarm cables, then these can be put in as well at any time. Just leave a pull core in.

You would need a separate duct then, as they are ELV.

 

[Spoon]

You would need a separate duct then, as they are ELV.

If they are screened and insulation rated to mains voltage then there shouldn't be a problem.

 

[Rpa07]

Not if SWA, doesn’t that act as a screened cable? (In this instance)

 

[Spoon]

Not if SWA, doesn’t that act as a screened cable? (In this instance)

Good question.

 

[Risteard]

If they are screened and insulation rated to mains voltage then there shouldn't be a problem.

Yes, but without knowing what cable will be used I suspect the cheapest option will be the most likely. Many of these cables are only rated for 50V.

 

[davesparks]

Yes, but without knowing what cable will be used I suspect the cheapest option will be the most likely. Many of these cables are only rated for 50V.

There’s nothing wrong with putting a 50V insulated cable next to an insulated and sheathed LV cable, however you can’t put it next to an unsheathed LV cable.

 

[PJGWiltshire]

Hi all its me again.
Having had your initial advise and intending to get some conduit tomorrow. I have had a call from an electrician through my builder.com, when I sought interest re rewire.
During conversation I was informed that replacing the cable to the garage was not notifiable under part P as it is a replacement of existing cable.
I looked up a guide on Elecsa -NICEIC and it quotes
'All other electrical installation work is non notifiable - namely additions and alterations to existing installations outside special locations, and replacements, repairs and maintenance anywhere.'

confused I am

 

[Octopus]

A rewire of a full installation or a single circuit is notifiable

 

[PJGWiltshire]

A rewire of a full installation or a single circuit is notifiable

SO to clarify, as i need to disconnect my existing 2.5mm cable, so that the ground work can proceed tomorrow. The route that the cable will now need to take is longer so I would need to replace the cable so that power can be restored to garage. I can lay conduit, if the cable reached the CU I can reconnect but if I have to replace the cable for a longer length I cannot connect as I need to notify??? that seems mad.

 

[Octopus]

I’m out.

Please give ALL the information next time you start a thread.

 

[ipf]

SO to clarify, as i need to disconnect my existing 2.5mm cable, so that the ground work can proceed tomorrow. The route that the cable will now need to take is longer so I would need to replace the cable so that power can be restored to garage. I can lay conduit, if the cable reached the CU I can reconnect but if I have to replace the cable for a longer length I cannot connect as I need to notify??? that seems mad.

I think you'd be mad if you reconnected that cable.

Anyway, if you're re routing a cable in such a manner, you're rewiring.

 

[PJGWiltshire]

I think you'd be mad if you reconnected that cable.

Thats what I'm trying to clarify. The advise given so far has been very helpful in that I am going to get an electrician to carry out the full rewire later this year, which was always going to be the case.
The issue that is causing me confusion is replacing the power to the garage. I outlined the issue on my original post and thought straight away of replacing the old 2.5mm with 6mm SWA. I was advised to get someone in to do this( reading the posts there has not been a clear answer around Part P compliance requirement) but as i need to crack on tomorrow in removing the old power cable, I will instal a conduit but anticipate I will be about 1m short to reconnect the old cable.
So my position is If I replace the cable with either twin and earth or 6 mm SWA is this Part P notification.

I do not wish to pay out for the connection that is not part P when a full rewire will be undertaken later. If it is the case that replacing the power cable is Part P I will have to think of other alternatives to get power to garage when required until the rewire.

Its the Part P issue that is confusing me.

 

[Midwest]

Good advise from others, although I sense they are getting a bit aspirated.

Have a read of this doc; specifically pages 6-10;
Electrical safety: Approved Document P - GOV.UK - https://www.gov.uk/government/publications/electrical-safety-approved-document-p, before you dig your trench

On a Compliance Certificate (Notification doc to LBC), there's a tick box for 'Partial rewire and/or Rewire of all circuits'. Your 'rewiring' your garage supply (its a new circuit), therefore its notifiable.

As others have suggested, install some ducting with a pull rope. If cost isn't prohibitive, I'd install two. The ducting, which eventually will have electric cable in it, so it should be installed in a certain way (at certain depths, coverings & markers). I would make contact with your future electrician, seek his/hers advice on how to install said ducting, or even get it done by him now.

Edit; some further guidance;
TLC Electrical Supplies - https://www.tlc-direct.co.uk/Book/7.13.3.htm

 

[Wilko]

Hi - possibly some confusion in that compliance with Part P of the Building Regulations is different from wiring compliance with BS7671. Both are necessary. In your case - replacing the cable - it sounds like no special actions are required by Part P, but the installation must still comply with BS7671.
Edit - oops, just read @Midwest post - so notification is required.

 

[shaun1]

Not sure how far you have got with this, but why not get back in touch with your electrician. He can tell you what he wants to see regarding ducting and SWA install, and perhaps pop round and inspect the trench, and then pull in the cable with you and make the connections. This is only a couple of hours work and then it will all be safe and tested. The electrician can the notify LABC, possibly even once the rewire is complete as one entire job, if its in the not too distant future. Im not sure if there are limits on timescales of an ongoing job.