one junction box two spurs

[binky]

Not sure its that simple as I believe the senario is one spur already exists off the JB but that doesnt mean that the new socket could not be incorporated into the ring by running 2 cables to the new socket and putting in a 2nd JB if one of the current ring wires isn't long enough to reach the new socket.TBH and not wanting to offend anyone but running 2 cables from 1 JB is just lazy and probably best done using 2 JB's and extending the ring to as least the new socket.

But whats the point of putting two JBs 2" apart, just looks untidy and electrically almost identical????

 

[binky]

No. You need to break into the ring at another point (either at another accessory that has not been spured off already or a new junction box if the joints accessable otherwise maininance free connections like wago's).

I use the ashley units for 'inspection free connection' which are designed to take 4 cables, but don't really see how this is different to 2 cables from a normal JB on a ring electrically speaking as long as cables are well terminated etc., or piggy backing at an MCB.

 

[ianmacd]

But whats the point of putting two JBs 2" apart, just looks untidy and electrically almost identical????

Nothing as long as its listed as a departure on the cert and you do not want the protection of 7671 if someone is injured/killed.

 

[Lurch]

This is one of those things I've never found an answer to since I started my apprenticeship. Technically there's nothing wrong with it, but it depends on what you're feeding the spurs to. You could spur 2 double sockets from 1 JB and then load each socket up with 20A thereby going over the rated current of the junction box. If you were running the 2 spurs to say, 2 SFCU's feeding a fan and a couple of lights then you'd technically overcome this problem.

But, whether it's technically correct or not depending on what the loading is, it's still wrong so best to avoid it and extend the ring or spur from another point about 3" up the cable.

 

[binky]

Nothing as long as its listed as a departure on the cert and you do not want the protection of 7671 if someone is injured/killed.

And how is this a departure??? You are allowed to spur to one point from a point on the circuit. 1 JB is 1 point, ergo 2 JBs allows 2 points to be spurred - never seen anything in regs about minimum spacings in between, and its less electrical loading than spurring off 2 side by side sockets.

 

[Lurch]

never seen anything in regs about minimum spacings in between, and its less electrical loading than spurring off 2 side by side sockets.

This bit I'm not getting. Surely the loading is the loading, regardless of whether the spurs are both from the same point, or from 2 JB's 2" apart, or from 2 sockets next to each other. The loading on that bit of the ring is pretty much the same regardless is it not, no difference whichever way you do it.

 

[binky]

This bit I'm not getting. Surely the loading is the loading, regardless of whether the spurs are both from the same point, or from 2 JB's 2" apart, or from 2 sockets next to each other. The loading on that bit of the ring is pretty much the same regardless is it not, no difference whichever way you do it.

Precisely my argument Lurch, which is why I am not adverse to doing this, as for JBs - there all rated at 30 amps, and are on 32 Amps ring mains, not that the jb takes the full loading anyway, cos the conductors are mostly in direct contact when jammed under the terminal screw, and CSA of the terminal is a damn site bigger than the cables. I am however willing to be shot down if anyone can give me a decent argument (now I've done it.... :^O )

 

[Lurch]

Precisely my argument Lurch, which is why I am not adverse to doing this, as for JBs - there all rated at 30 amps, and are on 32 Amps ring mains, not that the jb takes the full loading anyway, cos the conductors are mostly in direct contact when jammed under the terminal screw, and CSA of the terminal is a damn site bigger than the cables. I am however willing to be shot down if anyone can give me a decent argument (now I've done it.... :^O )

I see. I'm with you then, from a technical POV, it's fine under some circumstances. I may have also done it myself on occasions, but it isn't to BS7671 then.

 

[ianmacd]

As I suggested before this may be to stop any confusion about the use of spurs. If it says you can spur 2 cables off an accessory on a ring then people will read that as one cable going to first accessory then 2nd cable to a 2nd accessory.

 

[Lurch]

As I suggested before this may be to stop any confusion about the use of spurs. If it says you can spur 2 cables off an accessory on a ring then people will read that as one cable going to first accessory then 2nd cable to a 2nd accessory.

Again, there's situations where that would also be perfectly acceptable from a technical point of view.

 

[ianmacd]

Again, there's situations where that would also be perfectly acceptable from a technical point of view.

I think you are missing my point completly. Put your stupid hat on for a minute and become a have a go diy'er. You may have been told or heard that spurs off spurs on a ring are not allowed but if you came across someone having done what you ar suggesting then they may well funk it's ok to have spurs off of spurs as they will look similar. That Is my point. You can take the stupd hat off now.

I do not disagree with you technically but I believe it's just a best pricise for limited supprise.

 

[Lurch]

I think you are missing my point completly.

Maybe to some degree. However I think a lot is getting lost in the text form of conversation.

I do not disagree with you technically but I believe it's just a best pricise for limited supprise.

Agreed.

 

[binky]

As I suggested before this may be to stop any confusion about the use of spurs. If it says you can spur 2 cables off an accessory on a ring then people will read that as one cable going to first accessory then 2nd cable to a 2nd accessory.

But that's a different argument - the post is about is it safe to take 2 cables from one point, which is what I'm argueing about, rightly or wrongly. (PS I'm goind to stop arguing now cos I've been up since 5am, have just had half a bottle or Rioja, and am in the mood for upsetting someone or falling asleep :Y :Y:Y] ] ] :z :z:z)

 

[ianmacd]

But that's a different argument - the post is about is it safe to take 2 cables from one point, which is what I'm argueing about, rightly or wrongly. (PS I'm goind to stop arguing now cos I've been up since 5am, have just had half a bottle or Rioja, and am in the mood for upsetting someone or falling asleep :Y :Y:Y] ] ] :z :z:z)

You have caught the end of a possible reason it's not done as asked by niceguy. Go get some kip.

 

[ianmacd]

Just to throw another idea in the pot here. Ring run in 2.5 and a spur off in 2.5. Now you can not take another spur from that spur but what about a spur off the ring in 4 and the spur off the spur in 2.5 or 4? Think that probably sits in the same place as 2 spurs from one point on the ring, no real problem just not done.

 

[PBC_1966]

But whats the point of putting two JBs 2" apart, just looks untidy and electrically almost identical????

My thoughts exactly as I was reading that part of the thread. Whatever the current version of BS7671 says, it's rather ridiculous to argue that two spurs taken from the ring a few inches apart is acceptable but to make the arrangement neater by putting them into the same junction box is not.

There was never anything in the old Wiring Regs. for rings which prevented this arrangement, subject to the total number of spurs not exceeding the total number of sockets on the ring itself.

 

[Lurch]

Just to throw another idea in the pot here. Ring run in 2.5 and a spur off in 2.5. Now you can not take another spur from that spur but what about a spur off the ring in 4 and the spur off the spur in 2.5 or 4? Think that probably sits in the same place as 2 spurs from one point on the ring, no real problem just not done.

According to the regs you can;t do it. I have done it once though, or rather 2 spurs in 4mm, it was in my own house though, I'll get around to altering it one day, it was a quick and easy fix to add a couple of sockets for a lamp and a radio.

I wouldn't do it anywhere else though, almost an admission of guilt by upping the cable size!