Electrics 1st Fix - I become an electrician! Learn how!
Plumbing 1st fix continues
Window boards fitted
This week I continue to fit the 1st fix electrics. If you are put-off from touching electrics (as many seem to be) fear not! I found a recommendation to get
the Which Book of Wiring and Lighting on a self-build web site. I got it from the library - it is superb. As the Guardian's critic says on the cover
"If you don't see how to do it here - don't do it." It really is superb and covers everything I believe I will need to wire the entire house. I shall not repeat everything from the book but unashamedly admit that my new-found knowledge is almost entirely due to this book! See the Electrics Page in the Links section for details of how to buy this book on-line.
So let us begin.........
What you can not do.
Run the mains supply into the house. This must be done by the authorised local contactor - in my case 24severn.
Fit the electricity meter. Your selected electricity supplier will do this.
What you can do.
So where do you begin. Let's have some definitions we will need:
Flex. The cable you are used to with brown (live), blue (neutral) and green & yellow earth. This is only used to connect equipment to your circuits.
Cable. This has a flattened, oval section and comes in a variety of sizes and essentially two types:
Twin-core & Earth. Contains red (live), black (neutral) and bare (earth). This is used for almost all your wiring (in the appropriate size)
Three-core & Earth. Contains red, yellow & blue (any may be live!) and bare earth. This is used whenever two-way wiring is used such as light
switches at the top and bottom of the stairs.
Spit-Load Consumer units. These are the 1st stop after the meter. They have replaced old-style fuse boards. They have a number of ways (slots) into each of which can be placed the following:
MCBs (Miniature circuit breakers) every circuit except a ring-main (plug sockets) must have one of these of the appropriate rating typically 6Amp for lighting for example.
RCD (Residual current device). The entire house will have a big one of these & each ring main must have an individual one - they are both an isolating switch and a safety device. They basically monitor the earth circuit (which should not have any current normally) and will switch off in a fraction of a second if a current is detected of typically 30mA.
RCBO (residual current breaker with over current protection) this is basically a combined MCB & RCD.
FCU (Fused Connection Units). These are stand-alone items which are used for things which are permanently connected such as a cooker, wall-mounted fire etc
That is all we really need to know for this stage. Now you have to do is plan your circuits, where you want lights, sockets and switches etc.
The practical side can then begin. We will need individual circuits for the following items:
Plug sockets. One ring-main circuit for each floor plus 1 for the kitchen(s). RCD at 30A using 2.5mm cable
Lights (internal). One circuit for each floor. MCB 6A using 1mm cable
Lights (external) MCB 6A using 1mm cable
Smoke alarms. 6A using 1mm cable
Cooker. One each for our 2 kitchens. Main double range cooker 45A, the other single oven 30A. Both MCB
Electric Shower. 30A 10mm cable
Whole-house ventilation 6A with individual 3A FCUs
Heat Pump. Three phase. 415V
For 1st fix it is simply a matter of laying the cable in the right places and fitting the socket, switch and light mounting boxes. To fit the mounting boxes in stud walls you simply make a square hole in the plasterboard using a jig saw. Solid (block) walls present a different problem........
You could simply use a hammer and chisel. There is an easier way though! A drill that makes square holes!