OK. Firstly, the heaters should be on a separate circuit and definately not sharing with a lighting circuit. The fans could come off the lighting circuit if wished.
BTW, cable colours are changing. New colours are in brackets.
You have a 2 way and a 3 way lighting circuit.
The 2 way circuit in Room B is wired as follows, using 1.0mm2 or 1.5mm2 solid cored twin and earth mains cable, not flex.
Place the main junction box in a convenient accessible location. You can use a separate junction box, or use the one often incorporated into one of the light fittings. When you use the incorporated one, it is called "loop in", whilst if separate it is called the "junction box" method. Both are electrically identical.
There will be 4 terminal blocks.
- Earth. All earths should be terminated here. Ensure you use green/yellow sleeving over the bare earth conductors.
- Permanent live. The incoming unswitched lighting circuit comes in here (and may also go out to the next junction box for Room A)
- Neutral. All neutrals connect here.
- Switched Live. A switch cable is connected between this and the permanent live. Use the black (or blue) wire for the switched side, but use red sleeving over the top to indicate that it isn't a neutral. All the bulbs are connected between this terminal and neutral.
Now, the switch cable goes to the first switch. This switch should be a 2 way type, with 'C', 'L1' and 'L2' terminals. When using a dual gang switch, ensure you have got the right terminals for the particular switch and not mixing the 'C' from one switch with the 'L1' from another, for example.
Take the switched live to the 'C' terminal. Then, take a 3 core and earth cable from here to the last switch. The 3 core cable connects as follows.
(1st switch end) Red (brown) - connect to the permanent live from the switch cable, using an insulated crimp terminal and then using additional insulation tape or heatshrink over the top.
Yellow (grey) - connect to L1 Blue (black) - connect to L2
(last switch end) Red (brown) - connect to 'C' Yellow (grey) - connect to L1 Blue (black) - connect to L2
If you need an additional switch (such as for Room A), the wiring is identical, except that any additional switches required are connected as follows:
The cable between the 1st and end switch must be routed via the intermediate switches. Careful consideration of the optimum cable routing is required, as is choice over which switches should be the 1st and end switch.
The switches used must be the expensive "intermediate" type. These are often only available as a single faceplate item. When you want two switches in one single faceplate, you may have to search for a suitable item, use a grid type switch, or reorder the switches, so that the dual gang switches are always at the end of a run.
At the intermediate switch(es), connect the red (brown) cables to each other (but not to the switch). Sometimes, if careful, you can remove the sheath from the cable and not actually cut the red (brown) conductor at all, saving you the bother of crimping them back together. Then, follow the instructions that come with the switch to determine which terminals to connect the yellow (grey) and blue (black) wires to.
Note that the alternative sometimes suggested of running separate single cables from the junction box to the 1st and last switch in the chain is no longer considered acceptable, as it interferes with audio equipment, particularly hearing aids. The feed to the end switch should go down the same cable as the other conductors to avoid earth loops.
However, as it seems that you are using an electrician anyway, the critical things to remember are:
2&E from the incoming light circuit to the junction box. 2&E between the junction boxes. 2&E from the junction box to the first switch in the line. 3&E from the first switch, past any intermediate positions to the last switch. 2&E from the junction box to any light fittings. If multiple, then these can run in a daisy chain, or each directly back to the junction box.Ensure the cable you use is consistent in colour coding. Ensure it is at least 1.0mm2 CSA. Ensure that it is proper fixed wiring cable with solid cores, not flex or bell wire.
Christian.