Rewire lighting circuits with limited access

[zippy]

http://niceic.com/Uploads/File3777.pdf

Havn't plumbers been notching joists forever?

Yep, note 3 says it is ok, seems easier than larger holes with right-angle drill.

 

[Guest125]

That would certainly explain the 3 wires to the one rose I checked. Would the loop in the switches be running up to ceiling in conduit and then taking separate conduit path to next switch as that would surely be almost impossible to pull without the access?

Impossible to say. To re-use the existing conduits is a complete punt without spending a couple of days surveying the existing runs. Be careful on this one. It sounds like a minefield.

Be responsible and relay you concerns to the customer. I would say it would be worth an initial investment by the client of a few days to properly investigate the conduits and determine whether they can be re-used. If they can the customer will save a hell of a lot more on redecorations etc...

 

[Guest125]

I can't say I've ever heard it called 2 plate before.
There are two possibilities with a conduit system, the way Dave has shown above or the 'loop in' system which I described above

Really?

Two plate - loops at switches
three plate - loops at lights

I have always called these wiring methods by these names.

 

[davesparks]

Really?

Two plate - loops at switches
three plate - loops at lights

I have always called these wiring methods by these names.

I've heard other people call it 2 plate when T&E feeds are taken to switches.
I've always known standard conduit wiring as just that, a conduit system.

 

[Guest125]

I've heard other people call it 2 plate when T&E feeds are taken to switches.
I've always known standard conduit wiring as just that, a conduit system.

T&E at light switches is not 2 plate. The neutral loop at the switch would make it a three plate system.

Conduit sytems wired in singles can be wired in either two plate or three plate. This is why I think it better to call the circuit by a name as opposed to the containment it is wired in. But as long as you know all good.

 

[jase]

I think that falls under 'part A' so that would be a good place to look for the info

Electricians guide to the building regs.

 

[Anthony S]

Really?

Two plate - loops at switches
three plate - loops at lights

I have always called these wiring methods by these names.

That's what I was taught at Loughton College of Further Education in the 80's

Some excellent tutors back then

 

[zippy]

Really?

Two plate - loops at switches
three plate - loops at lights

I have always called these wiring methods by these names.

Aha, ok, then it that case I am familiar with 2 plate! Never heard loop at switch called that before.

 

[Guest125]

Aha, ok, then it that case I am familiar with 2 plate! Never heard loop at switch called that before.

I was taught:

2 plate - 2 termination blocks required at the rose. (L & N)
3 plate - 3 termination blacks required at the rose (L, N & Loop)

 

[zippy]

Folks,

Many thanks for all your replies. I will be doing a much bigger recon end of the week, so the info you have all shared is going to be a massive help.

Much appreciated. Will give update after next visit.

Zippy

 

[davesparks]

I was taught:

2 plate - 2 termination blocks required at the rose. (L & N)
3 plate - 3 termination blacks required at the rose (L, N & Loop)

That is my understanding of why 3 plate is called 3 plate, but it doesn't work for 2 plate.

A central joint box wiring method will require 2 terminals at each light, feeds to switches will require the same, as will a regular conduit system and a loop-in conduit system.

 

[zippy]

Hey folks,

Whole system is using conduit wire ... but no conduit. Live loop to switches and neutral loop to roses.

No movement in old wires so cannot use them mostly to pull new cables through.

Was going to channel under joists but decided to cut long thin rectangles out of the ceilings for the runs where I need to cross the joists and drill through centres of joists as it is fairly easy then to cut new pieces of plaster board to make good.

One thing to mention ... got one of those wood beaver drill bits to drill the joists and I am gobsmacked at how good it is, it is awesome.

Also making small rectangle openings in ceilings where old switch cables leave walls and enter ceiling voids and for those I can mostly use the old cable to pull the new switch runs through.

Job not as hard as I initially thought so fingers crossed.

Thanks for all your help and advice, you've been a massive help.

Zippy

 

[Engineer54]

Hey folks,

Whole system is using conduit wire ... but no conduit. Live loop to switches and neutral loop to roses.

No movement in old wires so cannot use them mostly to pull new cables through.

Was going to channel under joists but decided to cut long thin rectangles out of the ceilings for the runs where I need to cross the joists and drill through centres of joists as it is fairly easy then to cut new pieces of plaster board to make good.

One thing to mention ... got one of those wood beaver drill bits to drill the joists and I am gobsmacked at how good it is, it is awesome.

Also making small rectangle openings in ceilings where old switch cables leave walls and enter ceiling voids and for those I can mostly use the old cable to pull the new switch runs through.

Job not as hard as I initially thought so fingers crossed.

Thanks for all your help and advice, you've been a massive help.

Zippy

Hope you factored in all this extra work into your quote....