I am planning to rewire my complete house in the new year I intend to do most of the work by myself, running all wiring from lights and sockets and conecting them at the lights and sockets. I will be getting an electrition in to connect the fuse boxes and do safety tests on all circuits. I am wondering can I fit two new fuse boxes and run upstairs and downstairs as seperate systems, and am I able to use my old fuse box to wire up my proposed new workshop that will be at the bottom of my garden. could you also provide me information on cable sizes for Lights, Sockets, shower and from the house to workshop.
Fuse Box
- Thread starter Charlie4561
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There is no need to use two boxes, simply get a board with adequate ways to serve the whole house, if you are looking to do a deluxe install you could use all RCBos which will give you maximum descrimination, there are stacked boards available with two rows of breakers so the upper row would be up and the lower row down, but the SOP is a split board with two or 3 RCD protected sections with MCBs for the final circuits.
As to the old board, throw it out, new boards cost about £20-£30 for the carcase of a suitable size for a workshop and MCBs a couple of quid each, its not worth recycling, saying that if its modern, meets the requirements and isn't damaged you could re-use it.
Make sure you discuss everything with your spark first and agree a plan, agree for him/her to do stage testing and ensure that they will be prepared to sign off and are part P registered to do so - unless they have agreed the design and checked the work before its plastered over etc. they can't sign it off. If you are going down the Building Control road contact them now, before you start.
As to the old board, throw it out, new boards cost about £20-£30 for the carcase of a suitable size for a workshop and MCBs a couple of quid each, its not worth recycling, saying that if its modern, meets the requirements and isn't damaged you could re-use it.
Make sure you discuss everything with your spark first and agree a plan, agree for him/her to do stage testing and ensure that they will be prepared to sign off and are part P registered to do so - unless they have agreed the design and checked the work before its plastered over etc. they can't sign it off. If you are going down the Building Control road contact them now, before you start.
Have you much experience with domestic installations?
If your electrician is agreeable, it may be best for you to simply do the first fix, ie lifting floorboards, running cables, drilling holes, chasing plaster and fitting boxes. And leave him to do all the connections. After all, it's the electrician's name that will go on this work.
Leave the cable sizes for your electrician to decide, though lights will be a minimum of 1.0 mm, sockets a minimum of 2.5 mm. Shower and cooker usually 6.0 mm minimum. Here you will have to pay particular attention to the size of the load, in kW. A cable too small will severely limit your choice in shower/cooker. The cable route is important too, contact with loft insulation etc can influence the sizing of a cable.
10 mm earth cable to services like gas, water etc must be installed.
When burying cables in walls, safe cable zones must be observed, to avoid the cable being drilled through. In other words, if the cable is not in a safe zone, no one will know it is there, hidden.
Get the electrician to tell you where to drill holes in joists. Ask him what hole size is required. Fit all back boxes level, ie with a spirit level. Make sure they are at the same height.
Use oval conduit or capping to protect the cables when plastering.
Use rubber grommets on the entry holes of metal back boxes. It's difficult to fit them later.
Leave a little slack cable in floor voids near each accessory for any future alteration.
If your electrician is agreeable, it may be best for you to simply do the first fix, ie lifting floorboards, running cables, drilling holes, chasing plaster and fitting boxes. And leave him to do all the connections. After all, it's the electrician's name that will go on this work.
Leave the cable sizes for your electrician to decide, though lights will be a minimum of 1.0 mm, sockets a minimum of 2.5 mm. Shower and cooker usually 6.0 mm minimum. Here you will have to pay particular attention to the size of the load, in kW. A cable too small will severely limit your choice in shower/cooker. The cable route is important too, contact with loft insulation etc can influence the sizing of a cable.
10 mm earth cable to services like gas, water etc must be installed.
When burying cables in walls, safe cable zones must be observed, to avoid the cable being drilled through. In other words, if the cable is not in a safe zone, no one will know it is there, hidden.
Get the electrician to tell you where to drill holes in joists. Ask him what hole size is required. Fit all back boxes level, ie with a spirit level. Make sure they are at the same height.
Use oval conduit or capping to protect the cables when plastering.
Use rubber grommets on the entry holes of metal back boxes. It's difficult to fit them later.
Leave a little slack cable in floor voids near each accessory for any future alteration.
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There are a number of reasons for multi consumer units.
Power is first where the incomer is over the 100A rating for consumer unit so a fused isolator is used to limit current to each consumer unit to 100A max. The problem is to find a fused isolator that can be used where a normal person is to use them as most commercial stuff is not designed for normal person to use. Also using a three phase board one can get 180A rated units anyway so since one would need to break rules as to use of type tested gear may as well use distribution unit instead of consumer unit.
Note:- Consumer unit is a type tested distribution unit.
The other reason is to increase the number of RCD's protecting the house where the house is on a TT supply. With a TN supply one would use RCBO. But there are stacked consumer units and likely these can be configured to have 4 RCD's anyway. Can anyone confirm this?
Ability to isolate selected circuits is another. Radio hams for example if running unattended operation have to provide a way for the authorities to isolate their radio equipment. However it would be unusual to use that method.
History where up-dating existing systems bit at a time is another. I have two RCD's in a box supplying to old consumer units but with a complete rewire why would you want anything like that?
The normal is to somewhere provide a single point of isolation although reading the BS7671:2008 it does not say you must. It does refer to isolator in singular rather than plural and some see this as meaning you must use one to switch all. However after asking a number English degree holders they all agreed it means at least one and does not stop use of two devices. Yes English question not electrical.
But when designing any system you must consider why and if that is the safe way and the way anyone following will expect. There are three signatures on the installation certificate.
Designer
Installer
Tester
You have said you will get an electrician to inspect and test but before you start you need to find out if the LABC will accept your qualifications for the design and installation. I have had problems where they would not accept my son's C&G 2391 and 2382 but would accept my degree in Electrical/Electronic engineering yet for the job the 2391 and 2382 were really far better than my degree. (I do have 2391 and 2382 but they didn't know that).
As to cable sizes the BS7671:2008 gives a range of installation methods for example:- Reference Method 100# (above a plasterboard ceiling covered by thermal insulation not exceeding 100 mm in thickness) and to work out cable sizes you must first select installation method.
Normally 1.5mm for lights and 2.5mm for power but not always. For cookers 6mm at least today with use of induction hobs and insulation in walls 10mm may be better option and since you will likely need 10mm for any shower supply likely buying a role of 10mm will be cost effective.
The BS7671:2008 also called the 17th Edition is a good guide but a little hard to work out so there are also guides to the guide and if you want to design the installation you will need to read through them.
There is also the building regulations which are split into Parts. M give socket heights and F says how fans are wired and P says how electrics are tested. There is also one on energy can't remember the letter.
Some regulations only refer to new builds other cover all. To ensure do have a trouble free passage with LABC you should submit a detailed plan. If your plan says sockets at 300mm and the inspector does not object then after you have fitted them all he can't complain but if you don't stipulate the height he may after you have fitted them insist on the 450mm in Part M. Hence why detailed plan helps you.
We all tend to break or bend rules but where the LABC is inspecting you have to really do the work to better standard than we do. And fitting a consumer unit can be a nightmare. The problem is we can't draw the DNO fuse officially and the LABC can't let you switch on without viewing test results and will then need to see live test results before he allows you to use anything.
The LABC vary and some are very helpful, other can really be pain and I would suggest that getting an electrician who can self certify his installation to fit the consumer unit may remove a lot of the problems.
Testing is a problem as really you want to test circuits as you go rather than just at the end and the test equipment is not cheap. Also if living in the house you want to make circuits live before whole job is complete. With my test set I have no worries but I would not like to do a re-wire without them and I question the whole idea of DIY without tools of the trade. I tried to hire when mine away for calibration and at £75 per week I quickly found another way around it.
All the best you are a brave man.
Power is first where the incomer is over the 100A rating for consumer unit so a fused isolator is used to limit current to each consumer unit to 100A max. The problem is to find a fused isolator that can be used where a normal person is to use them as most commercial stuff is not designed for normal person to use. Also using a three phase board one can get 180A rated units anyway so since one would need to break rules as to use of type tested gear may as well use distribution unit instead of consumer unit.
Note:- Consumer unit is a type tested distribution unit.
The other reason is to increase the number of RCD's protecting the house where the house is on a TT supply. With a TN supply one would use RCBO. But there are stacked consumer units and likely these can be configured to have 4 RCD's anyway. Can anyone confirm this?
Ability to isolate selected circuits is another. Radio hams for example if running unattended operation have to provide a way for the authorities to isolate their radio equipment. However it would be unusual to use that method.
History where up-dating existing systems bit at a time is another. I have two RCD's in a box supplying to old consumer units but with a complete rewire why would you want anything like that?
The normal is to somewhere provide a single point of isolation although reading the BS7671:2008 it does not say you must. It does refer to isolator in singular rather than plural and some see this as meaning you must use one to switch all. However after asking a number English degree holders they all agreed it means at least one and does not stop use of two devices. Yes English question not electrical.
But when designing any system you must consider why and if that is the safe way and the way anyone following will expect. There are three signatures on the installation certificate.
Designer
Installer
Tester
You have said you will get an electrician to inspect and test but before you start you need to find out if the LABC will accept your qualifications for the design and installation. I have had problems where they would not accept my son's C&G 2391 and 2382 but would accept my degree in Electrical/Electronic engineering yet for the job the 2391 and 2382 were really far better than my degree. (I do have 2391 and 2382 but they didn't know that).
As to cable sizes the BS7671:2008 gives a range of installation methods for example:- Reference Method 100# (above a plasterboard ceiling covered by thermal insulation not exceeding 100 mm in thickness) and to work out cable sizes you must first select installation method.
Normally 1.5mm for lights and 2.5mm for power but not always. For cookers 6mm at least today with use of induction hobs and insulation in walls 10mm may be better option and since you will likely need 10mm for any shower supply likely buying a role of 10mm will be cost effective.
The BS7671:2008 also called the 17th Edition is a good guide but a little hard to work out so there are also guides to the guide and if you want to design the installation you will need to read through them.
There is also the building regulations which are split into Parts. M give socket heights and F says how fans are wired and P says how electrics are tested. There is also one on energy can't remember the letter.
Some regulations only refer to new builds other cover all. To ensure do have a trouble free passage with LABC you should submit a detailed plan. If your plan says sockets at 300mm and the inspector does not object then after you have fitted them all he can't complain but if you don't stipulate the height he may after you have fitted them insist on the 450mm in Part M. Hence why detailed plan helps you.
We all tend to break or bend rules but where the LABC is inspecting you have to really do the work to better standard than we do. And fitting a consumer unit can be a nightmare. The problem is we can't draw the DNO fuse officially and the LABC can't let you switch on without viewing test results and will then need to see live test results before he allows you to use anything.
The LABC vary and some are very helpful, other can really be pain and I would suggest that getting an electrician who can self certify his installation to fit the consumer unit may remove a lot of the problems.
Testing is a problem as really you want to test circuits as you go rather than just at the end and the test equipment is not cheap. Also if living in the house you want to make circuits live before whole job is complete. With my test set I have no worries but I would not like to do a re-wire without them and I question the whole idea of DIY without tools of the trade. I tried to hire when mine away for calibration and at £75 per week I quickly found another way around it.
All the best you are a brave man.
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The ONLY way that will work is if you find your electrician first and agree with her what work you can do.
She will be the only one who may do the calculations, the design, the identification of cable routes etc. She will be the one you have to ask your questions of. She will be the only one who can supervise and direct your work. She will be the one signing a certificate to say that she did all of the work and that it all complied with BS 7671 (that does not prevent her using you for manual labour), and she will be the one who has to self-certify to LABC that she did the work and it complied with the Building Regulations.
Just forging ahead, with or without advice from here, and then presenting her with a fait accompli expecting her to accept responsibility for it will not work.
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