Can you spur off a socket

Topic Tools. View similar topics Print this topic. I know it has been said that amateur electricians are like amateur brain surgeons - there are no survivors, and I'm happy to say I consider myself almost an unqualified professional, but I have a question: I know and understand the reasons why you should only feed one single or double socket as a spur off any socket on the ring and hence the maximum number of spurs should not exceed the number of sockets on the ring , but if you're going to run a spur by breaking into the ring with a junction box and then running the spur from that, why should there be a limit?

Thanks, Rob. Confucius say, many electricians make light work. Top : Bottom. There is no limit to the number nor a reason not to have more than one from a 'point' as long as it is designed properly. I thought we had been through all this in a recent post? The difference is obvious when you know. There are TWO situations to consider. If you fuse it to 13A you can put as many as you want on it.

The reason I explained was that standard final ring circuits wired in 2. I don't know whether the term 'spur' is being confused with a fused connection unit. I really don't get why everyone seems to struggle with this fundamental concept. Can I ask what in particular makes you think you can put a junction box and add a radial spur on the ring and just add as many sockets as you like?

It used to be the rule no more spurs than points on the ring. So a ring with 10 points could have one spur each point. I'm referring to unfused spurs of course. A good practice thing really. Oh, I see. Actually strictly what we meant was " is accepted as a standard circuit requiriung no further detailed analysis" not simply " not permitted. I recall the "one spur to one ring device" being inferred in a diagram in one of John Whitfield's guides circa odd.

Make sure that all three wires are secured in each terminal, and avoid damaging the wires when replacing the socket. Only one socket outlet can be connected to a spur. This can be a single or double outlet. Connecting a further outlet is NOT permitted, as this could overload the single cable supplying it.

Each socket outlet or junction box on the ring can only have one spur connected. Reaction score 12, It's to do with the current carrying capacity of the cable and the protective device that protects the cable from overload.

Difficult to explain without going into circuit design but essentially a single point from a spur from a ring circuit using standard cable sizes is permitted as the potential current drawn won't exceed that of the cable. Multiple points would and in a ring circuit the overcurrent protective device would not be coordinated to protect the cable in that arrangement. Upvote 0 Downvote. SparkyChick Mod. Reaction score 7, A typical ring final is wired in 2.

The ring on the right is still balanced, and the cables that make up the ring itself are not overloaded. But spurs are usually wired in the same cable as the ring and as such, you should be able to see that it's possible with spurs on spurs to overload a cable segment. The circuit breaker may take a while to trip, in the meantime the cable would heat up which will cause damage to the insulation. In a typical radial circuit using the same cable, we would limit the circuit breaker to 16A or at most 20A, thus the cable is protected from an overload.

If you want to have lots of sockets on a spur off a ring, you can use a fused connection unit to create the first spur from the ring.

This would limit the current to 13A maximum and thus protect the cables after it from an overload. Hope that clarifies it a little.

Last edited: Feb 29, Reaction score 9, Very detailed, SparkyChick but I think the maths have let you down. Basically, OP, its the current carrying capacity of the cable.

Click to expand SparkyChick said:. View attachment A typical ring final is wired in 2. Remove the knockout from the box. Push the box back into the hole, feeding the cable through the opening.

Push in or turn the securing lugs so that they grip the rear face of the plasterboard firmly. Connect the wires and fit the faceplate. Check the socket is correctly wired using a socket tester. A socket can become damaged for a number of reasons: a blow can break the faceplate or overheating may cause scorching.

If the problem is scorching, it will usually have been caused by overloading the socket, or by loose connections in a plug.

Unscrew the socket faceplate and pull it away from the wall. Loosen the terminal screws and free the cable cores. If the insulation is heat damaged, cut back the cores and strip the ends. Connect the red core or cores to the live terminal of the new faceplate, the black to the neutral terminal and the earth to the earth terminal. Tighten the terminal screws fully. Refit the new faceplate. Although you can increase the number of sockets in a room by converting single sockets to doubles, there may be times where you need an extra socket where none exist already.

The circuit must have RCD protection. An alternative to running a spur from an existing socket is to run it from a 3-terminal, amp junction box wired into the main circuit cable. Isolate the circuit at the consumer unit and use a socket tester to double check that the power is off.

Then remove the faceplate from the socket you want to run a spur from. What you need to find is a socket with two cables entering it.

But before you add a spur, you must first confirm that this is a ring circuit. Disconnect the black cores and — with the power still off — test them with a continuity tester. The same regulations apply, however, so trace the cable to the nearest socket and run the above tests.

Although the IEE Wiring Regulations let you have an unlimited number of socket outlets on each main circuit running from your consumer unit, there are restrictions on the floor area that each circuit can supply.

You should find that the rooms of the house covered by each circuit are written inside the fuse cover of your consumer unit, but you can check this by isolating the circuit and using a socket tester on each socket to see if it works.