Planning for a Rewire

[malcolm]

I have come to the conclusion that all of the switches and sockets in the house are in the wrong place or of the wrong number. Many of the wires are in the wrong place too. The house used to be a pub and we have idiosyncratic features like a big switch panel behind the bar which controls all of the downstairs lighting.

A complete rewiring will probably be needed before I finish my masterplan. The problem is I don't have the funds to do everything at once and will need to focus my efforts to get past building regs for the change of use before the start of next year (insulation and fire doors).

Requirements for building regs involve internal insulation on a few walls where I might like to have a couple extra sockets which shouldn't overload the existing circuit. I could probably cope with no extra sockets. The kitchen will need to be replaced after the wall insulation but that is fed by 3 relatively sensible circuits so shouldn't be too difficult.

How do you go about having a complete rewire done in stages as you go along? Is that even a sensible thing to attempt? I half imagine I could find a sensible electrician who would be able to help plan the new wiring to the masterplan which would allow some bits to be done now and some other bits to be extended as I go later on. Does that sound reasonable?

 

[Tony.]

Find space for a new fuseboard next to the existing and energise it the spark can double up the tails with Henley blocks.

Run power circuits in a radial circuit per room, chopping old cabling back as far as possible and making safe if the old cabling needs to be re energised.

Use a central joint box method for the lighting circuit.

This is a power cable from the board to a large joint box, then another cable to the light and another to the switch. This will get lighting on in one room, as other rooms are added more cabling is installed.

I would Rcbo everything

 

[malcolm]

That is a brilliant idea Tony. I hadn't considered a second consumer unit. The old circiuts could be moved one by one from the old to the new as I go along and it would be obvious which are old and which are new.

 

[Flyfisher]

How do you go about having a complete rewire done in stages as you go along? Is that even a sensible thing to attempt? I half imagine I could find a sensible electrician who would be able to help plan the new wiring to the masterplan which would allow some bits to be done now and some other bits to be extended as I go later on. Does that sound reasonable?

That's exactly what I've been able to do but, as you might also imagine, the trick is to find the 'sensible elctrician'. In our case I was recommended a local father and son team ( mainly son these days) and used them for a small re-wire of a few rooms plus a new CU. During those works we discussed my plans for the rest of the house and we evolved a pattern of working whereby I would explain what I was planning in terms of changes/additions, we'd agree outlet and switch placements and cable routing, I would then install all the cabling and outlets ( often the trickiest and most time-consuming part of the job) and he would then come along to connect, test and certify the installation. The arrangement is ideal for me and, presumably, is lucrative enough for him. I presume it's easier to negotiate such an arrangement with a local small firm / one-man band than a large national company, but no harm asking - what's the worst that can happen?

One other point, prompted by Tony's post about radial circuits. We have many rooms with only one socket (and some with none!) wired on a radial circuit rather than a ring main. I wanted to add quite a few more sockets and assumed they would have to be converted to a ring, with all the complication of an additional wire back to the CU. The electrician said this was not necessary as long as the circuit was protected by a 16A MCB instead of the standard 30A for a ring main. This made perfect sense because outside of a kitchen/utility room there are very few things these days that draw much power, even though we have many more 'toys' to plug in these days. In fact, no matter where a socket is placed, I find it hard not to also require one of those 4-way socket strips, even though the total power draw is very low.

I also agree with Tony's point about additional CUs. We already had two in the house, added another for the kitchen extension and have a fourth one in the garage/workshop with master isolators where the power enters the property. It might sound extravagant but the extra cost is minimal in the grand scheme of things and makes it very easy to make various changes and additions as the project evolves.

 

[mims&pip]

We have also been fortunate enough - on more than one occasion :wink: - to find sensible electricians willing to do the rewire in stages.

First time it was the Victorian house that had previously been converted to four tenanted flats and (as you would expect from a dodgy landlord) everything that had been done previously was a bit *iffy*! The place was large enough - and equipped with various kitchens/facilities spread across several floors - that we were able to camp out in one area with all our stuff whilst the sparky tackled another. As we were also relatively short of cash back then and it was a big project, staged payments made a lot of sense.......

When we bought our last house our finances were in a somewhat healthier condition, but the nature of the Georgian, heavily beamed building with later extensions again lent itself to splitting the rewiring into manageable chunks. We also found a father and son team - although in our case the father mainly concentrated on plumbing, which was also useful as we were adding new bathrooms - who were not only willing to carry out the work in stages, but were also the most immaculately tidy trades people I have ever dealt with

At our current house we're still undecided whether to rewire or not, but we did have one chap in to quote last Summer and he volunteered the suggestion of doing the job in stages, so I would definitely conclude that it's quite the norm when faced with larger/more complex properties!

Mims x

 

[malcolm]

Thanks for the replies. It sounds like organising the electrical side of things might be easier than I thought as the work needed to get past building regs for the change of use is reasonably localised. Using a new consumer unit for the new work makes a lot of sense and there probably is enough room in the electrical cupboard. I'll talk to some local builders to see if they can recommend electricians.

I've been trying to figure out where to put a temporary kitchen while the current one is out of action. Only the oven and storage would end up in an unheated space so there might be some sense in getting on with it at this time of year. After the kitchen is completed a further room will open up for office or dining while the rest of the work goes on.

 

[LadyArowana]

There's never a tame animal around when you need one.

 

[Penners]

Run power circuits in a radial circuit per room

This is certainly a sensible recommendation, assuming you want to power up the new circuitry bit-by-bit. The alternative would be to install new rings (and radial lighting circuits )around the house bit-by-bit as you work on each room, but leaving the old system operational until the end, when the completed new rings can be finally be connected up to a new CU. It would, of course, be very important that you plan the whole new system meticulously before you begin.

And always remember the inescapable principle of planning electrical installations: no matter how many you install, there will never be quite enough plug sockets; and no matter how carefully you plan your room layouts, there will always be a socket behind the chest-of-drawers. :wink:

 

[mims&pip]

And always remember the inescapable principle of planning electrical installations: no matter how carefully you plan your room layouts, there will always be a socket behind the chest-of-drawers. :wink:

Not guilty, m'lud - but a previous owner of Springe Vale Cottage (as spelt on our commemorative plaque :wink: ) did ensure they were not repositioned when radiators were added - yes, we have an inaccessible socket behind a rad - and impossible to use because the addition of carpet rendered a different socket (on skirting board beneath a rad :roll: ) too low to actually fit the plug into! Why didn't they just install the rads in different locations?!?

Mims x

 

[malcolm]

I'm not very good at planning ahead, but to some extent an old building forces a make it up as you go along approach. I hope to be able to avoid placing sockets behind radiators. People do nutty things. We have a socket above the door in a stairwell for reasons I cannot imagine.

It's frightening to have to think about complicated things like how the kitchen lighting should be. Or even what the kitchen layout might be. Hopefully one thing will follow on from another once I find out if I can knock a little hole in a difficult wall to make a kitchen diner. It is an ancient wall so it would be a shame to disturb it, but it was once an outside wall so might have a door or window opening already. I'm not allowed to remove the (modern) plaster while the room is still in use as a kitchen, so I'll have to start and then make it up as I go along.

 

[Tony.]

You need to write a specification to ensure you can compare contractor quotes that they are like for like

For example if you price a new consumer unit with 12 ways this could be
2 RCD main switches protecting say 6 mcbs each RCD
Or 12 RCBOs

Both would be compliant both have pros and cons for each but one could be a quarter of the price.

 

[malcolm]

I've found the local electrician so will chat to him. One think he will probably help me with is working out wiring routing which will be a pain here. One worry I have is the wiring will probably be replaced again in another 30 or 40 years so my internal wall insulation and nice lime plaster will be ripped out and replaced with something horrid. I ripped out a surprising amount of plaster this morning just to get at one wire.

In a lot of places the wires will have to go behind insulation. I'm wondering about the use of decent sized conduits where wires can be pulled through without having to rip have the wall apart. They would probably need to be accessible for modifications. Rather than reinvent the wheel are there any accepted ways of doing that sort of thing?

 

[Penners]

In theory that sounds a very good plan, Malcolm, but in practice it may not end up working. Once a run of conduit has turned a few corners, it becomes surprisingly (and annoyingly!) difficult to pull cabling into or out of it - particularly 2.5mm^2 TW&E - unless, that is, your conduit is very generously sized in comparison to the cabling within it. And there's rarely the space within a wall for this.

However, if you think you can overcome this, please don't let me discourage you from trying!

 

[Zebra]

There's never a tame animal around when you need one.

What? Er... Oh! Yes. What they said.

 

[Penners]

Tame?? :?

 

[malcolm]

Thanks Penners, I think for most of the walls I could use over-sized cable trunking behind the internal insulation which would allow wires to be replaced where there is access to the ceiling from above. There are a few areas where there is no access from above which might be more fun. For those I might run the wires on the room side of the insulation and then make good.

I wonder whether it would make sense to run all of the wires on the internal side of the insulation. It would help a lot with sealing and make them easier to get at without complete destruction.

I moved a couple of light switches from one room to another at the weekend. The old switch wires passed through and then up a wall, and removing them will create a lot of work in re-plastering and replacement woodwork. I don't like to see old wires left in place as they cause confusion. I'll cover the (non-live) ends with blanked switches for now with a note inside about what the wires are, but it has prompted a bit of thinking ahead.

 

[Penners]

I think for most of the walls I could use over-sized cable trunking behind the internal insulation which would allow wires to be replaced where there is access to the ceiling from above.

In which case I urge you to find a trunking system that offers nice, slow bend pieces, rather than sharp right-angles.

 

[Flyfisher]

Much will depend on the physical locations involved but I'd agree that buried trunking is a generally good idea. I've installed buried trunking within a few walls and ceilings, though mainly for data cabling (the 'trunking' to the main hub is actually plastic drainpipe!) and it makes it very easy to add additional wires. I try to leave a 'draw string' inside the conduit where possible but otherwise it's usually possible to 'insert' a draw string through a section of conduit by tying one end to a piece cloth loosely inserted into one end of the conduit and then using a vacuum cleaner to suck the cloth+string through to the other end.

I would certainly echo Penners' point about the difficulty of threading something like 2.5mm2 T&E (and even 1mm2), even with a fairly large conduit. Such wiring is usually installed with single wires as the trunking is effectively a replacement for the outermost sheath of the standard T&E cables we usually use. Single wires, even 2.5mm2, are so much easier to install within trunking. However, I'm pretty sure this is only allowed by the regulations if the entire circuit is run within conduit as any exposed wiring must be double-insulated, thus is only really a suitable option if the conduit can be fitted right up to all the outlets and/or switches - but where this is possible a full conduit system makes for a robust and fairly easily maintainable installation . . . albeit rather more 'workshop' than 'drawing room'.

 

[Zebra]

Not a bad idea to install cables in front of the insulation. Otherwise, could you create sort of boxed-in areas where all the cables run? I agree with Flyfisher that you can only use single core cables instead of twin-and-earth if the trunking or conduit system is fully enclosed throughout the entire run. This is not impossible to achieve (25mm plastic conduit perhaps) but could be bulky to install if you have any hope of pulling through it in future, and you would still need access hatches every so often in order to wire it, so I'd be more leaning towards planning cable runs in areas where the replastering wouldn't be quite so drastic. You could perhaps run cables in the "safe zone" within 150mm of the ceiling to avoid lifting floorboards or destroying ceilings in future.

 

[malcolm]

I like double insulated wire, it is a marvelous invention. I would be reluctant to use single insulated wire hidden away in a conduit which could become chaffed on pulling through or eaten by wire eating conduit mice.

The barn mostly has wires running through the safe zone under plastic covers and plastered over. It isn't easy to modify as there is no spare wire length, but assuming I get the light switches in the right rooms it shouldn't need modification. It shouldn't be too much hassle to plaster over the strip when the wiring is replaced every 50 years or so. It probably does make sense having the wiring on the room side of the new insulation.

I think I might need to add some small boxed in areas in fiddly areas to make it easier to get a bunch of wires and heating pipes past obstacles. The upstairs corridor has a long run of MDF boards where the original floor boards have been removed which is ideal for access once carpets have been lifted.