Parallel spurs?

[mrshr]

Hi All,
I'm in the process of replacing socket and switches from the tatty old brass fittings to satin chrome ones (under orders from the missus).

On removing a single gang socket in the utility room I see that there are four sets of twin and earth in there.
I'm assuming two sets are the ring and the other two are spurs in parallel with each other?

Is it ok to have two spurs like this?

 

[EFLImpudence]

You're not supposed to but it's not the end of the world.

 

[mrshr]

Thing is, if it is two spurs off one socket I think one of the spurs is what I plug the washing machine and tumble dryer into.
If both are running at the same time, that'd be pulling quite a load wouldn't they?

Not sure what the other spur is yet.

 

[plugwash]

AIUI having two spurs starting from the same point is not explicitly forbidden by the regs but it's not shown in any of the examples either (the examples are not normative though).

Putting two large appliances on a double socket, especially one on the end of a spur is not the best of ideas. If practical i'd try and rearrange things so that the washing machine and drier are on seperate sockets fed from seperate points on the ring.

 

[EFLImpudence]

That is true but you shouldn't have a WM and TD on one spur or in the same double socket anyway, at least not on at the same time.

 

[mrshr]

What if I sacrifice this supplying socket for a fused spur so that both parallel spurs are protected by the 13A fuse?
Presumably I wouldn't be able to run wm and td together as this would exceed 13amps?

 

[EFLImpudence]

What if I sacrifice this supplying socket for a fused spur so that both parallel spurs are protected by the 13A fuse?
Presumably I wouldn't be able to run wm and td together as this would exceed 13amps?

The point with two spurs from the same point is that it is not advisable because of the loading of the circuit as a whole if it were near one end of a Ring circuit.
However, if near the centre of the circuit, it doesn't really matter.

Also, two spurs from two sockets right next to each other would be no different.


Fitting a fused spur would limit the current and protect the socket but not really the answer.
A better solution would be to install another cable to the socket and replace the double with two singles so that they are 'on the ring'.

 

[ericmark]

If we consider the appendix as part of the regulations then "The load current in any part of the circuit should be unlikely to exceed for long periods the current-carrying capacity of the cable" this it says means items like cookers, ovens and hobs with a rated power exceeding 2 kW should be on their own circuit.

As to the washing machine it does not take long to heat the water in the same way as a kettle so they will not exceed 2 kW for long periods. However the tumble drier will exceed 2 kW for long periods yet we seldom see dedicated circuits to feed the tumble drier.

To my mind there are two reasons for not taking more than one spur from a single ring connected device.
1) It may not load share when near origin and could overload the ring. When I did some calculations however I found it to be unlikely to happen in practice.
2) Fitting 4 wires in one connector means there is a possibility that they are not all properly connected. Even with just two wires I have removed sockets to find a wire pop out so with four wires this is a real danger.
So instead of having a double socket box with a double socket and two spurs having a twin socket box with two single sockets and a spur off each would it would seem to comply.

Much will depend on the room available and the installers ability but I would want to test after renewing sockets to ensure I have not got a wire which has disconnected breaking the ring. Using the loop impedance meter the electrician testing before and after plus during to check the circuits are still as a ring one can be reasonably certain all is well. However without the loop impedance meter the only place where one can be reasonably certain that one has not disturbed a wire when removing and replacing is at the consumer unit.

However the consumer unit often has exposed live parts even when the isolator switch is off, and I would not want to recommend DIY guys to open up the consumer unit to test. So in view of what you are doing I would note an easy assessable socket on the ring with no spurs, and ear mark that socket for final testing, and once all sockets are swapped return to that socket to test the ring is still complete.

As long as you test, although not strictly correct, I would not be unduly worried about two spurs from same socket. But to my mine it is all down to testing it is just too easy where four wires go into one terminal to end up with two radial circuits instead of a ring and the very real dangers of overload as a result.

 

[mrshr]

The four conductor wires are twisted together.
Its really difficult to push them into the new socket, so another reason to make a change to the setup.
I've had a bit more of a look this morning. I think I will be able to run another cable to one of the spurs (the one that wm and td plug in to).
I dont yet know what the other spur is going to.

The wife says she often runs both appliances together

So if I CAN get another cable to the wm and td spur, then I can make that socket a part of the ring, right?
Do I need to make that double into two individual singles? I think that's what was suggested here?

If if find another socket on the ring (without a spur on it), how do I test the ring?
I dont have an insulation resistance tester.

Ive uploaded a pic.

 

[Lectrician]

The regs (certainly the OSG) did used to state that only one spur old be taken from each point on the ring, but this has vanished. The OSG neither says you cannot nor can take two spurs from a single point.

 

[mrshr]

So it seems that it's not actually wrong?
But doesn't the fact that I'm running a wm and td from one of the spurs suggest I need to change it?

 

[ban-all-sheds]

If we consider the appendix as part of the regulations then "The load current in any part of the circuit should be unlikely to exceed for long periods the current-carrying capacity of the cable" this it says means items like cookers, ovens and hobs with a rated power exceeding 2 kW should be on their own circuit.

As to the washing machine it does not take long to heat the water in the same way as a kettle so they will not exceed 2 kW for long periods. However the tumble drier will exceed 2 kW for long periods yet we seldom see dedicated circuits to feed the tumble drier.

 

[JohnW2]

The regs (certainly the OSG) did used to state that only one spur old be taken from each point on the ring, but this has vanished. The OSG neither says you cannot nor can take two spurs from a single point.

True - but even when the regs did say that, they allowed two spurs to be taken from two sockets which were only 6 inches apart - so it never made much sense in terms of possible unbalanced loading/overloading of a ring.

However, there is still a requirement to comply with manufacturer's instructions, and I think you might struggle (and probably fail) to find any sockets with a 'rated' terminal capacity to accommodate 4 x 2.5mm² conductors (MK certainly aren't) - which effectively means that two spurs from one socket is 'not allowed'.

Kind Regards, John

 

[mrshr]

To get around the four cables into one terminal problem, could I simply use a five way wago. So connect the four conductors into the wago, and then connect a new piece of twin and earth to the new socket terminals?
Obviously I'd do this for Line, Neutral and Earth so a total of three 5-way wagos.

Would the be acceptable?

 

[JohnW2]

To get around the four cables into one terminal problem, could I simply use a five way wago. So connect the four conductors into the wago, and then connect a new piece of twin and earth to the new socket terminals? Obviously I'd do this for Line, Neutral and Earth so a total of three 5-way wagos. Would the be acceptable?

If I understand what you're saying, you would then make even the existing socket a spur, so you'd actually have three sockets all spurred from the same point in the ring - even 'worse' than two.

If one was doing it with 'junction boxes', it would be better to install a JB in one of the legs of the ring that was feeding the socket, and then moving one of the spur cables from the socket to the JB (which would mean identifying which cables were the ring, and which were the spurs). That would mean that both the socket and the JB would have just three cables (two ring and one spur).

There could also be issues of accessibility of this 'junction box' you had created.

Kind Regards, John