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Old wiring issues

Hi all,

I am trying to install PIR motion switches in all communal area's in my home and all I know about electrics is how to change a fitting without electrocuting myself, beyond that I have no idea.

Having started to look at my house (bought knowing it needed a lot of work) I have so far discovered that the wiring system in my house is very old and very questionable.

The first room I did I had no problems, there were two 3-core cables for load and mains feed, I followed the instructions that came with the PIR and no issues, it is working.

The bathroom and kitchen is another story, there is only one 3-core cable going into the switch (pull cord type), the wiring is in the loft and that is a mess of junction boxes - any idea what is going on here as there does not seem to be a way to wire the PIR with this, I presume as the internal motion sensor switch needs a feed and load to be able to function properly.

I have learned that due to the ample space above (loft) and below (cellar) the house (bungalow) whenever extra plumbing and electrics were needed short cuts were taken and things just bolted on wherever there was space, some of the light fittings even seem to be piggy backed from existing switches and don't come direct from the mains. Building regs would have a heart attack...

Also I know it is impossible to say for certain but can anyone estimate how much it would cost to re-wire a bungalow?? (kitchen/bathroom/hallway/living room/3xbedroom).

Thanks in advance

4 Answers from MyBuilder Electricians

Best Answer

Difficult to say 100% as location and spec can change a price a lot but I normally charge for a standard spec around 3-3.5k to rewire a 3 bed bungalow. I hope that gives you a rough idea I am in Cambridgeshire.

Kelvin Partridge
Iconnect Electrical Solutions


Answered 30th Aug 2015

Certainly sounds like the norm as over 85% of houses in the UK have electrical defects and very few actually pass a thorough electrical test and inspection. From what you describe it may well be that the lighting is wired "junction box method" this in itself is not unsafe if done properly, but it is unlikely to be suitable for the retro fitting of PIR sensors that often rely on a neutral connection.

Hopefully you have already applied to your local authority and paid the appropriate fees for consent to carry out DIY electrical work in your home (as required by part P of the building regulations) otherwise you could well be in for a £5000 fine as all electrical works has to be tested, signed off and registered with building control.

As part of your alterations, you will also need to install an RCD in order to meet the requirements of BS7671:2008.

Should you have no consent in place? then best advise is to STOP and hire a professional. Approx cost of rewire would be around £2800


Answered 30th Aug 2015

pir needs 3 core and earth,your existing pull chord is 2 core and earth,trace pull chord wire back to ceiling pendant and remove.install 3 core and earth from ceiling pendant.brown from live,black from switched live,grey from neutral,connect brown to live at pir,black to switched live at pir,grey to neutral at pir.please turn all power off at consumer unit first.


Answered 30th Aug 2015

For a 3 bed rewire depending on your spec would looking from around £2800 to £3500



Answered 31st Aug 2015

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