to rewire or not...

[JupiterJon]

i've been lifting a few floor boards in the renovation project and am a little dismayed by what I saw

rewired my current home and found it fairly straight forward and as the new place had been rewired I was expecting it to be fairly easy to understand and add a few extra sockets etc before getting it inspected. While the consumer unit has only modern PVC twin core and earth there is an obvious bodge in the second picture and given the state of other bodges around the rest of the house I am wondering whether to try to persist, removing the old cable, tracing the new or just rip out and start again?

if I do start again I would like to run the cables in as few a holes through the joists so I have room for running some cat5 and UHF cable. The joists currently look like cheese from the number of different holes, could I use a hole cutter to put a BIG hole for all the cables through? What size cold I get away with (I knew I should have measured the joist but it's approx 6" deep and 2" width).

Thanks Jon

[John White]

second photo, are both causes for concern and require further investigation.

Alas, if life were only so simple... :-(

Well I would certainly remove any redundant wiring and fittings that may be under the floor as it is often difficult to tell if a horrible bodge is still in a live circuit or not. Really whoever rewired the place should have ripped out most of the old cables as part of the job.

(I don't subscribe to the rip-out-every-last-inch brigade, as doing so can result in a lot of additional making good. I would however rip out all the redundant stuff from under a floor.)

Don't jam the holes full of cables as this can lead to mechanical damage or overheating in some circumstances. Alarm, telecoms, data cables and the like should be run through different holes from the mains cables.

I would have though that, with a bit of careful planning, you already have enough holes through these joists for any conceivable purposes.

I would stick to 20mm or at most 25mm diameter holes in such a joist. Ideally the holes should be drilled through the centre of the joist and close to any supporting walls. That is along the edges of a room rather than down the middle

I see in your photos that your current joists have some holes close to where slots for pipes and the like have been cut. This is a bad idea as it can seriously weaken the joist.

John

[meow2222]

testing your various outlets (lighting, shower, sockets etc) to check for earth and correct L/N polarity should both be easy to diy and give you a bit more idea as to how bad it is or isnt.

NT

[<me9]

Building regulations don't allow holes near the edges of joists, only notches. IIRC holes have to be in between 0.25 and 0.4 of the span, and notches between .05 and .25 of the span (but you can't have a hole and a notch close together).

Looks like some thoughts of replacement/strengthening wouldn't come amiss.

[JupiterJon]

Thanks for this and the other advice, I had been thinking of doing a partial rewire adn strip out of the old but there is grey PVC cable that has been disconnected and left in there and it has taken ages to fathom in one room alone. There a several instances of unfused spurs of rings and I discovered that a socket next to the front door is off the 2nd floor sockets circuit breaker ... I do not have a lot of confidence in the installation and am beginning to think it will be better to start with a clean sheet and have

100% confidence in the result, rather than 95%... I may keep the wiring in the rooms where it is clear, but the main cable routes are a nightmare to work out with the numerous era's of wire. Any time team tips out there?!

Jon