Octopus wiring lights

Bobby34 · Feb 12, 2019

So I was doing some work at my sisters house and one of the jobs she wanted was her lights looking at, i looked at them and quite honestly thought if I start touching these i'm going to end up rewiring the lighting circuit. I'm newly qualified and happy to put my hands up if something is looking like I may be out of my depth but basically, you had light switches in the kitchen turning the living room lights on, when you turn a different light on in the kitchen then one of the two kitchen light fittings would dim and a separate light would turn off it was just all over the place.

Long story short I said to get a more experienced sparks round to have a look but if she could let me know what the issue was I'd be interested in knowing, she came back to me today and said that he said it was what is known as Octupus wiring and is his pet hate and was a common way of doing things back around the 60's.

Could someone just explain a bit more what octopus wiring actually is and any pro's con's?

Many thanks

Nebu1a · Feb 12, 2019

Never heard this phrase before. Sounds like its wired from central junction box and some of the switch lives are incorrectly connected.

Strima · Feb 12, 2019

Nothing wrong with an octopus wiring method just not seen often as we tend to loop in and out using a three plate.

Needs some fault finding doing on it, would be good practice for you.

Nebu1a · Feb 12, 2019

Pros are usually a single cable at the switch or light fitting so easy to terminate fittings. Cons are a junction box hidden somewhere under the floor making future maintenance a pain in the proverbial.

Nebu1a · Feb 12, 2019

So is octopus wiring 3plate?

Nebu1a · Feb 12, 2019

Sorry misread. Junction box method is ok in a loft space or if the Jbs have been put in say the airing cupboard or similar

Strima · Feb 12, 2019

JB should ideally be placed in an accessible area but they often get boarded over in lofts. Very easy to add smokes etc.

7029 dave · Feb 12, 2019

It is a junction box wiring system.

A032701 · Feb 12, 2019

each jb has four terminals.
terminal 1 - permanent live, this runs out to the next jb for the next room. another cable also runs to the switch
terminal 2 - switch live. this comes from the switch and goes to the lights.
termonal 3- this is neutral.
terminal 4 this is cpc

DPG · Feb 12, 2019

Alban, that's not octopus wiring.

A032701 · Feb 12, 2019

sorry that is a junction box system as per 7029 dave said it would have been.
an octopus system consists of a large terminal box where all the cables run into from the switches and lights

telectrix · Feb 12, 2019

this is octopus.1 central JB for all lights on the floor.the green is lights.

Bobby34 · Feb 12, 2019

Yea that seems like the sort of thing, ok glad it's an actual thing and glad I didn't jump straight in after looking at that pic haha, I will speak to the sparks when I get a bit more time and gain some experience points

, thanks guys

SparkyChick · Feb 12, 2019

And in reality it could look something like this (although this particular box contains power and lights).

Bobby34 · Feb 12, 2019

Oh wow great picture, many thanks sparkychick

Lucien Nunes · Feb 12, 2019

Yes, that's genuine 'Octopus', the trade marked wiring system, although the term is also used generically to mean one big junction box with a lot of cables. The idea came into its own with the advent of prefabricated housing where all dimensions were exactly identical. The octopus box was factory-made and tested with tails of the right lengths to reach the lighting points and switches. On site, the sparks would place the octopus in position, unroll the cables and pull them in.

Cost a bit more in cable but saved time on site, plus one end of every cable run was terminated under ideal conditions at the factory so potentially more reliable.