Electrical rewire: Merits of chasing walls from above versus coming up from floor

Hi Everybody,

We are getting quotes and specifying a re-wiring job on our house at the moment and would like to get some opinions on two different schemes that have been proposed.

Some of the electricians are proposing to wire our sockets by digging channels into the walls (chasing I believe is the term?) and then putting the electrical cable into a tube embedded into the wall which we then plaster over. This cabling would be fed from above - so on the ground floor the sockets would be fed down from the first floor, on first floor they are fed from attic (I think).

Others are proposing to replace the existing cables that are there and come up from the floor which is the way the existing sockets are connected. This would apply on both the ground and the first floor.

In both cases the sockets will be moved from their current position on the skirting to the height defined by current specifications (15/16 inches I think from the floor).

Based on quotes to date the floor based cabling seems to be cheaper and this is probably because there is much less labour involved for the electrician.

However I am wondering if there are any pros or cons to either scheme apart from the cost - so even if it costs that bit extra is the better scheme to go with the cabling coming from above via the embedded channel?

I thought of the following points but they might be on the wrong track:
(1) Wiring coming from below means you have to lift floor for future maintenance - we will be laying wooden floors so maybe not ideal?
(2) Wiring coming from below means if there were ever a water leak on the ground floor you have a higher risk? (Flooding is not a worry in our area)

Thanks as usual for any advice and opinions.

Re: Electrical rewire: Merits of chasing walls versus coming up from floor

Am I right in thinking that if the cabling is coming up from the floor it will be run external to the walls?

Re: Electrical rewire: Merits of chasing walls versus coming up from floor

Hi Newbie,

No - if the cabling is coming up from the floor it would be recessed into the wall also (probably embedded into wavin tubing in the same way it would be if coming down from the ceiling/behind the wall).

Of course shorter distance there to 'chase' so less labour involved most likely.

Thanks for the reply.

Sorry, misunderstood the original quote. In that case I can't offer any expertise so will leave it for leccies to comment!

For what it's worth, we have just finished getting the walls chased and it was a dirty dirty business - If you will be living there when its happening I'd suggest putting everything you own into plastic.....best of luck!

While there is more labour involved in the longer chase there is less labour involved in running cables through the attic. i.e you don't have to run cables through joists etc...The shorter the chase the less of a mess you have as suggested above chasing is very messy. You would also have less plastering to repair.

I don't think you should have an issue with leaks, if you have one in the ceiling then you'd discover it fairly quick. Personally I would not be too bothered where the cables come from, top or bottom. What is the difference in cost?

Hi Con,

Difference in price is about 2-4k depending on which contractor does the work. Pretty large variance!

What would you think about the question on the wooden floors - if we laid them and had to get in at the wiring we would probably ruin the wooden floor if it is glued down?

Sorry about the delay,

The chances that you will need to get at those cables are pretty slim unless you are re-wiring again. I know that having the cables running around the attic means that they are accessable for the future which is good in case you want to make an addition but I bet that if you ran a spare cable to the attic for this purpose it would not cost you thousands. If your electrical contractor does his testing before the timber floors go down and has no problems then you should have no reason to lift those floors. If it makes you feel any better, I've just wired my house and ran the cables from underneath for the upstairs because the builder would not chase down for me and as I said above I ran a spare supply to the attic for anything in the future.

In rewiring a house I think the quickest way is always the best. Chasing is a very, very messy operation and as long as the cable is protected properly under the wooden floors you should have no problem. cable as component is very reliable. The weakness in the system is at the ends i.e. the socket or at the Distribution board. I have not yet seen a case of cable failure so the only other weakness is of a mechanical nature where something breaks the cable i.e. a nail and once the timber floor is down you are less likely to put a nail in the floor than in the wall. So in my humble opinion go with the floor option.