Two spurs from one junction box ?

Is there any reason from either a regulations or best practice point of view why I shouldn't run two spurs from the same junction box on a ring circuit?

I aready have a wago box with four pole Wago 773 connectors and a single spur connected to the ring. Although I could divert the ring to go through the new socket I'm installing it would be a lot more convenient to connect a spur to the vacant fourth pole in the connectors.

The Wago connectors are rated at 24A. Each spur will have one double socket so I suppose there's the potential of this being exceeded in the very unlikely event of both the sockets being fully loaded.

Reply to
Mike Clarke
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On Wednesday 21 August 2013 15:59 Mike Clarke wrote in uk.d-i-y:

It's not normally recommended due to

a) overfilling the terminals leading to one or more wires becoming loose even though the screw is tight;

b) too many cables in the back box. Single spur is bad enough much of the time.

However in your case (separate JB) these problems go away. You are left with the possibility of overloading the spur cable which is good for 20-27A typically depending on how it is run.

You could mitigate this by using 4mm2 cable from the wagos to the spurs. Not standard, but it would be fairly bomb proof.

Reply to
Tim Watts

Stop and think about it. What are you going to use to fully load both sockets at the same time?

If ALL the sockets are fully loaded that is 4 x 13A = 52 Amps.

Reply to
ARW

Well it wouldn't be any different to cutting the ring two inches away and adding another spur.

Is that 24A per hole in the wago or the total. If the later you probably need something bigger.

If you replace the breaker with a 20A you can virtually do what you like as it becomes a radial.

Reply to
dennis

On Wednesday 21 August 2013 19:03 ARW wrote in uk.d-i-y:

I would make the argument (and I'm not a professional):

Will the circuit protective device protect all parts of the circuit from overload?

A single spur: generally yes - as even a double socket is usually only rated to carry 20A combined (correct me if there are ones that truely can carry more). 2.5mm2 cable is usually good for 20A (often a fair bit more).

Multiple accessories on a single spur: It is now feasible to overload the spur cable without the protective device operating.

Of course, this is only a problem if someone sticks a load of massive loads on both sockets in the spur -

Reply to
Tim Watts

Assuming your spurs are ok from a total loading point of view, and they are not in a position that they are likely to unbalance the ring, then there is no regulatory reason why you can't do what you propose. The normal argument against it, is that wiring can be difficult getting 4 sets of wires into the terminals on a socket, but that does not appear to apply here.

Reply to
John Rumm

Yes, that's one of the things I like about Wago connectors. Each wire goes into it's own hole without disturbing the others, much easier than trying to keep 3 or 4 conductors in place while you tighten up the single terminal screw in a conventional box.

Reply to
Mike Clarke

The specs are a bit vague on this so I assume that it's 24A total.

Reply to
Mike Clarke

Well I'm never likely fully load any of them, probably not even one of them. They're only likely to be used for typical living room stuff - TV, audio, computer, table lamps etc and frequently not even used at all.

My main concern was that it might not be compliant because of the theoretical potential for this configuration to overload the connectors.

As it turns out this is now an academic point. Following "discussions" with SWMBO about possible layout of furniture when the job'a finished we're going to need yet another socket further along the wall so a spur isn't an option and it's a case of extending the ring.

Reply to
Mike Clarke

You answer that below, it doesn't.

If the double can only handle 20A it isn't protected by the breaker or the fuses.

Reply to
dennis

On Wednesday 21 August 2013 23:14 dennis@home wrote in uk.d-i-y:

You are right. I don't like it[1]. But it is regs compliant. And the cable feeding it *is* protected.

[1] How hard is it to make a double socket be capable of taking 2x13A loads?

Of course, the regs would have to amended to say not double sockets on spurs (unless downstream of a 13A FCU).

Reply to
Tim Watts

The connectors would have been fine.

That's what they do:-)

Reply to
ARW

The correct thing is to ask is "why would you want to make a double socket capable of taking 2x13A loads?" That's 81% of a 32A ring maximum load gone in one double socket. It's not just the way things work in the real world.

Not if the 2.5 T&E feeding the circuit is rated at 27A CCC:-).

Reply to
ARW

Trust me. It does not become a radial. It will still be a ring.

Reply to
ARW

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