Replacing Radial circuits ?

[mattylad]

Reading the wiki about radial circuits it appears to be simple enough that you can do this with a 20A MCB.

I have a couple of questions to ask of this though.

1) Is there a limit on the number of double gang sockets that can be on a single radial? (or is it a case of as long as the load is no more than 20A MCB?)

2) Can more than 1 radial circuit be installed on a single MCB? (taking overall load into consideration).

If 2 = no, please explain why so this numpty knows exactly why he shouldn't

My reason for asking this is because being in a circa 1850 house, I have stone floors (6" thick 5'x4' slabs) that I am unlikely to be able to cable through & may have to use existing cable paths when replacing the old wiring.

 

[mattylad]

Further to the above, can you:
3) Spur off the radial to another double gang socket?
(Am only thinking of the other side of a partition wall so 12" of 2.5mm cable.)

 

[industryspark]

Q Is there a limit on the number of double gang sockets that can be on a single radial? (or is it a case of as long as the load is no more than 20A MCB


not off the top of my head there isnt no, although the floor area served shouldnt really exceed 50metres squared. 20A isnt a great deal, you wouldnt need many appliances to go above that but it depends on the type of appliances you are running.


Q Can more than 1 radial circuit be installed on a single MCB?


yes thats fine, but it wouldnt be 2 circuits, it would be just the one but would be a 'branch' circuit with 2 cables coming from the mcb.


Q Spur off the radial to another double gang socket?

yes thats ok, if you think about it all a radial is, is a spur after spur after spur after.....you get the idea.

 

[Taylortwocities]

I feel that we are going to have that old discussion that's called:
"you can only have a spur off a ring final"

I dont think that the term 'spur off a spur' applies...

 

[industryspark]

note to self, ''be more carefull with wording/phrasing''

 

[Taylortwocities]

Yeah, you know how picky people are on here (me too!)

 

[mattylad]

OK cheers, although I was having a numpty moment when I posted that extra bit, I'll simply go into 1 socket, out & into the other then off to the rest in a continual radial.

Its the lounge so will only have tv/sky etc on & small lamps on the others

The most that will be used on this cct will be hair straighteners (although heaven knows why they cant use them upstairs in their own bedrooms )
Hopefully I'll be able to find a path down to the cellar again so I can continue it along to the other cct to complete a ring instead (that way I wont have to buy another MCB).

 

[davelx]

I feel that we are going to have that old discussion that's called:
"you can only have a spur off a ring final"

I dont think that the term 'spur off a spur' applies...

In the ECA guide to the 17th, under the standard circuits section, they show two diagrams of radial finals.

One is wired entirely in 4mm and has branches which it does not call spurs. The other is the same but with some branches wired in 2.5 mm (with and without FCU) which it does call spurs! I don't know if that same illustration is in the 17th as I've not got mine yet.

But it looks like you maybe can have spurs off a radial.

Cue BAS......

 

[mattylad]

Spurs are not an issue (for me) as I wont be doing that (I dont like them myself). What is the issue to me is how I protect the cable if its behind skirting?

Should it be in steel conduit?

Cheers.

 

[Taylortwocities]

The cable should not be behind the skirting unless teh sockets are also embedded in the skirting (they should not be due to fire risk).

So, why is there cable behind the skirting if the sockets are in the wall, and cables have to run horizontally or vertically from the socket??

If you must put them there then, yes, earthed steel conduit is one solution.

 

[ban-all-sheds]

But it looks like you maybe can have spurs off a radial.

Cue BAS......

Ah - memories of dear old Fing - how we laughed.

I wonder whatever happened to him?

Anyway - if people want to start a ring/spur/radial discussion, read this.

If you still want to, read it again.

Repeat until you've had enough....

 

[mattylad]

If you must put them there then, yes, earthed steel conduit is one solution.

Cheers, what other solutions are there?

I'm not too keen on chasing the whole wall out all the way across the room horizontally between sockets, its not IMO a good solution in these walls, the stones (not bricks) tend to fall out if you disturb the dry manure that is wedged between them

 

[Taylortwocities]

Sounds like a perfect candidate for conduit or trunking..

 

[Click-Sure]

Skirting trunking

Spurs are not an issue (for me) as I wont be doing that (I dont like them myself). What is the issue to me is how I protect the cable if its behind skirting?

Should it be in steel conduit?

Solid steel section skirting

 

[mattylad]

Steel trunking it is then, I think that there is enough room underneath the wooden blocks for holding the skirting in to be able to push the trunking in, I can easily get it cut to size, threaded & 90 angles put on to be extra neat with it.

Thats another query from this house of horrors solved.
Cheers,
Matty