Difference between revisions of "Adding sockets"

From DIYWiki
(See also)
(How many sockets: too many)
 
(26 intermediate revisions by 4 users not shown)
Line 1: Line 1:
{{Under-construction}} <!-- this includes the 'Under Construction' template -->
+
This article covers the ways in which you can safely extend existing [[House Wiring for Beginners|socket circuits]] to provide more outlets.
  
(this is a draft outline - feel free to add topics you would like to see covered)
+
==How many sockets==
 +
The choice is entirely yours. Just bear in mind that numerous socket additions have been made, only to find later that more are wanted. The amount of [[Appliance|domestic electronics]] in use is continuing to increase, so what's adequate today probably won't be later.
  
This article covers the ways in which you can safely extend existing socket circuits to provide more outlets.  
+
But there is such a thing as [https://www.rightmove.co.uk/property-for-sale/property-65826048.html too many]
 
 
==How many sockets==
 
You the user decide this. Just bear in mind that numerous socket additions have been made, only to find later that more are wanted. The amount of domestic electronics in use is continuing to increase, so what's adequate today probably won't be later.
 
  
 
==Ring & Radial Circuits==
 
==Ring & Radial Circuits==
British socket circuits are always ring or radial. A ring circuit makes a complete loop from CU (fusebox) to each socket and back to the CU. A radial only has a single run of cable from CU to the sockets, no return cable.
+
British socket circuits are always [[Ring circuit|ring or radial]]. A ring circuit makes a complete loop from [[CU]] (fusebox) to each socket and back to the [[CU]]. A radial only has a single run of [[cable]] from CU to the sockets, no return [[cable]].
  
 
===Extending radial circuits===
 
===Extending radial circuits===
Radials can be extended from any point in the radial circuit. See cable size section.
+
Radials can be extended from any point in the [[Ring circuit|radial circuit]]. See [[cable]] size section.
  
 
===Extending ring circuits===
 
===Extending ring circuits===
New sockets can be added as part of the ring, or as a spur. Its very much recommended to add them as part of the ring where this is practical. This means breaking the existing ring, and often adding a bit more cable.  
+
New sockets can be added as part of the ring, or on a spur. Its very much recommended to add them as part of the ring where this is practical. This means breaking the existing [[Ring circuit|ring]], and often adding a bit more [[cable]].
  
A relatively easy way to add new sockets as part of a ring is to cut the existing cable run and fit 2 new sockets, one to each end of the cable, then link the 2 with a new piece of cable.
+
A relatively easy way to add new sockets as part of a ring is to cut the existing [[cable]] run and fit 2 new sockets, one to each end of the cable, then link the 2 with a new piece of cable. Extensions can also be included in  a ring from a single existing socket position. See [[Easy socket extensions|this technique]].
  
 
====Spurs====
 
====Spurs====
Sometimes running a single piece of cable from an existing point in the ciruit to a new socket is the only practical option. This is called a spur, and is subject to some limitations.
+
Sometimes running a single piece of [[cable]] from an existing point in the ciruit to a new socket is the only practical option. This is called a non-fused spur.
* an unfused spur should only feed one single socket
+
 
* a fused spur can feed an unlimited number of sockets. Many multi-way sockets have a fuse built in to provide the needed fusing.
+
A non-fused spur should feed only one single or one twin socket-outlet, or one Fused Connection Unit. Three- and four-socket 'power strips' should be connected by a Fused Connection Unit or incorporate a 13A cartridge [[fuse]].
  
Many single spurred sockets have been replaced with a double socket. This is not regs compliant, but is common.
+
The total number of non-fused spurs must not exceed the total number of socket outlets and items of stationary equipment that are directly connected to the circuit.
  
 
===Splitting a ring===
 
===Splitting a ring===
Occasionally it can be worthwhile to split a ring circuit. By breaking the circuit at some point, the one circuit then becomes 2x radial circuits. At the fusebox the 2 tails can be separated, each getting its own fuse. Splitting the circuit like this changes the fuse rating permissible for each half, in most cases this makes it not worthwhile, but where a ring was run in 4 mm^2 you can get more total ampacity by splitting it into 2 radials.
+
Occasionally it can be worthwhile to split a [[ring circuit]]. By breaking the circuit at some point, the one circuit then becomes 2x radial circuits. At the [[CU|fusebox]] the 2 tails are separated, each getting its own [[fuse]]. Splitting the circuit like this changes the fuse rating permissible for each half, in most cases this makes it not worthwhile, but where a ring was run in [[Cable|4 mm^2]] you can get much more total ampacity by splitting it into 2 radials. One 30A or 32A 4mm ring can become 2x 32A radials.
 +
 
 +
When splitting a ring, regs require checking the voltage drops at the end of the new radials. Also check the current carrying capacities of the cables if they are buried in [[insulation]], as the insulation leaves them able to handle less current.
 +
 
 +
If you can find a convenient point about mid-way on the ring and run two cables new back to the consumer unit, you can split the ring into two rings.
  
 
==Cable Choice==
 
==Cable Choice==
2.5 mm^2 the most popular socket circuit cable. Its sufficiently rated for 30/32A ring circuits as long as its not buried in 100mm or more of insulation. Its also good for 20A fused radials as long as its not buried in 100mm or more of insulation.
+
2.5 mm^2 is the most popular socket circuit cable. Its sufficiently rated for 30/32A ring circuits and 20A radials when installed as per [[Cables#Installation_Methods|reference methods]] A, B, C, 100 and 102.
 +
 
 +
4 mm^2 is used for 30/32A radial circuits, and also for 30/32A ring circuits where the [[cable]] will be in contact with [[insulation]] or a large circuit is needed and voltage drop is a limiting factor.
 +
Trying to get 3x 4 mm^2 wires into socket terminals can be a challenge!
  
4 mm^2 is used for 30/32A radial circuits, and 30/32A ring circuits where the cable will be buried in insulation. Trying to get 3x 4 mm^2 wires into socket terminals can be a challenge!
+
*Info on maximum ring circuit lengths and allowed installation methods is [[Ring_circuit#Maximum_cable_lengths|here]]
 +
*4mm 30/32A radials may only be installed as per reference methods [[Cables#Installation_Methods|B & C]]
 +
*BS 3036 [[Fuse#Rewirable Fuses|rewireable fuses]] aren't permitted on 30A 4mm radials or 20A 2.5mm radials due to the correction factor applied to the [[cable]] when using these type of [[fuse]]s.
 +
*6mm 30/32A radials need to be used if the cable is installed as methods A, B, 100 and 102. A BS 3036 rewirable fuse may be used on a 30A 6mm radial if installed as method C.
  
1.5 mm^2 cable is sometimes used on radial circuit where the circuit is fused at 15A and the cable won't be buried in 100mm or more of insulation. Where the cable is buried, 1.5 mm^2 can only be fused up to 10A. 1.5 mm^2 is typically used where an old immersion heater feed is reused to supply sockets.
+
1.5 mm^2 cable is sometimes used on radial circuits and is typically used where an old [[Immersion Heaters|immersion heater]] feed is reused to supply sockets.
 +
This circuit should never be used with a BS3036 rewirable fuse greater than 6A. A 15A BS1361 fuse, 16A BS-88 fuse or a 16A MCB may be used provided the cable is installed as per reference methods 100, 102, B or C given [[Cables#Installation_Methods|here]].  
  
Its ok to use larger cable than required if its able to fit into the terminals of the accessories in use.
+
It's ok to use a larger [[cable]] than required if it's able to fit into the terminals of the [[Electrical connection|accessories]] in use.
  
 
==Socket Positions==
 
==Socket Positions==
  
 
==Cable Routes==
 
==Cable Routes==
* describe allowable zones
+
[[Safe zones for electric cables]]
 +
 
 +
[[Cable Routes and Protection#Cables in a wall or partition|Cable routes and protection]]
  
 
==RCD Protection==
 
==RCD Protection==
New sockets circuits normally require an [[RCD]], though there are exceptions. Adding sockets to existing sockets does not require fitting an [[RCD]]. The [[RCD]] goes in the CU or fusebox - but some old fuseboxes can't accommodate an RCD.
+
New sockets circuits require an [[RCD]] now. Adding new sockets to existing sockets also requires an [[RCD]]. The [[RCD]] goes in the [[CU]] or [[CU|fusebox]] - but many old fuseboxes can't accommodate an RCD. If that's the case, current regulations require you to fit a new CU.
  
==Implementation==
 
 
==Circuit joins==
 
==Circuit joins==
Cable joins in a circuit can be of 2 types:
+
See main article [[Electrical connection]]
* accessible, meaning it can be reached readily using a tool
+
 
* inaccessible, eg buried under tiling
+
[[Cable]] connections in a socket circuit can be of 2 types:
 +
 
 +
*accessible, meaning it can be reached readily using a [[Hand tool|tool]]
 +
*inaccessible, eg buried under [[:Category:Tiling|tiling]]
  
Accessible joints are usually made using screw connections, either in the socket itself, or a junction box, or screwblock strip contained within an electrical backbox (for fire protection.)
+
Accessible joints are usually made using [[screw]] connections, either in the socket itself, or a junction box, or screwblock strip contained within an [[Pattress|electrical backbox]] (for [[fire]] protection.)
  
Inaccessible joints may not use screw connections, as they can come loose in time. Permitted connection methods are:
+
Inaccessible joints may not use [[screw]] connections, as they can come loose in time. Permitted connection methods are:
* crimping
 
* welding/brazing
 
* soldering
 
  
Of these, crimping is by far the simplest and the least prone to problems in inexperienced hands.
+
*[[Cable crimping|crimping]]
 +
*welding/brazing
 +
*soldering
  
The other approach to cable joins is to replace it with a new piece of cable that's long enough. Sometimes this is practical.
+
Of these, [[Cable crimping|crimping]] is by far the simplest and the least prone to problems in inexperienced hands.
 +
 
 +
The other approach to [[cable]] joins is to replace it with a new piece of [[cable]] that's long enough. Sometimes this is practical.
  
 
===Junction boxes===
 
===Junction boxes===
 +
See main article [[Electrical connection]]
 +
 
===Disused cables===
 
===Disused cables===
 +
Ensure disused cables are disconnected at both ends and, if they could become live inadvertently, link all the cores to earth at the supply/consumer unit end.
  
 
==See also==
 
==See also==
* [[Rewiring Tips]]
 
* [[CU]]
 
* [[Cable]]
 
* [[Cable crimping]]
 
* [[Easy socket extensions]]
 
* [[House Wiring for Beginners]]
 
* [[Pattress]]
 
* [[RCD]]
 
* [[:Category: Electrical]]
 
* [[Special:Allpages|Wiki Contents]]
 
* [[Special:Categories|Wiki Subject Categories]]
 
  
 +
*[[Rewiring Tips]]
 +
*[[CU]]
 +
*[[Cable]]
 +
*[[Cable crimping]]
 +
*[[Easy socket extensions]]
 +
*[[House Wiring for Beginners]]
 +
*[[Ring circuit]]
 +
*[[Pattress]]
 +
*[[RCD]]
 +
*[[:Category: Electrical]]
 +
*[[Special:Allpages|Wiki Contents]]
 +
*[[Special:Categories|Wiki Subject Categories]]
  
 
[[Category: Electrical]]
 
[[Category: Electrical]]

Latest revision as of 13:49, 4 November 2019

This article covers the ways in which you can safely extend existing socket circuits to provide more outlets.

How many sockets

The choice is entirely yours. Just bear in mind that numerous socket additions have been made, only to find later that more are wanted. The amount of domestic electronics in use is continuing to increase, so what's adequate today probably won't be later.

But there is such a thing as too many

Ring & Radial Circuits

British socket circuits are always ring or radial. A ring circuit makes a complete loop from CU (fusebox) to each socket and back to the CU. A radial only has a single run of cable from CU to the sockets, no return cable.

Extending radial circuits

Radials can be extended from any point in the radial circuit. See cable size section.

Extending ring circuits

New sockets can be added as part of the ring, or on a spur. Its very much recommended to add them as part of the ring where this is practical. This means breaking the existing ring, and often adding a bit more cable.

A relatively easy way to add new sockets as part of a ring is to cut the existing cable run and fit 2 new sockets, one to each end of the cable, then link the 2 with a new piece of cable. Extensions can also be included in a ring from a single existing socket position. See this technique.

Spurs

Sometimes running a single piece of cable from an existing point in the ciruit to a new socket is the only practical option. This is called a non-fused spur.

A non-fused spur should feed only one single or one twin socket-outlet, or one Fused Connection Unit. Three- and four-socket 'power strips' should be connected by a Fused Connection Unit or incorporate a 13A cartridge fuse.

The total number of non-fused spurs must not exceed the total number of socket outlets and items of stationary equipment that are directly connected to the circuit.

Splitting a ring

Occasionally it can be worthwhile to split a ring circuit. By breaking the circuit at some point, the one circuit then becomes 2x radial circuits. At the fusebox the 2 tails are separated, each getting its own fuse. Splitting the circuit like this changes the fuse rating permissible for each half, in most cases this makes it not worthwhile, but where a ring was run in 4 mm^2 you can get much more total ampacity by splitting it into 2 radials. One 30A or 32A 4mm ring can become 2x 32A radials.

When splitting a ring, regs require checking the voltage drops at the end of the new radials. Also check the current carrying capacities of the cables if they are buried in insulation, as the insulation leaves them able to handle less current.

If you can find a convenient point about mid-way on the ring and run two cables new back to the consumer unit, you can split the ring into two rings.

Cable Choice

2.5 mm^2 is the most popular socket circuit cable. Its sufficiently rated for 30/32A ring circuits and 20A radials when installed as per reference methods A, B, C, 100 and 102.

4 mm^2 is used for 30/32A radial circuits, and also for 30/32A ring circuits where the cable will be in contact with insulation or a large circuit is needed and voltage drop is a limiting factor. Trying to get 3x 4 mm^2 wires into socket terminals can be a challenge!

  • Info on maximum ring circuit lengths and allowed installation methods is here
  • 4mm 30/32A radials may only be installed as per reference methods B & C
  • BS 3036 rewireable fuses aren't permitted on 30A 4mm radials or 20A 2.5mm radials due to the correction factor applied to the cable when using these type of fuses.
  • 6mm 30/32A radials need to be used if the cable is installed as methods A, B, 100 and 102. A BS 3036 rewirable fuse may be used on a 30A 6mm radial if installed as method C.

1.5 mm^2 cable is sometimes used on radial circuits and is typically used where an old immersion heater feed is reused to supply sockets. This circuit should never be used with a BS3036 rewirable fuse greater than 6A. A 15A BS1361 fuse, 16A BS-88 fuse or a 16A MCB may be used provided the cable is installed as per reference methods 100, 102, B or C given here.

It's ok to use a larger cable than required if it's able to fit into the terminals of the accessories in use.

Socket Positions

Cable Routes

Safe zones for electric cables

Cable routes and protection

RCD Protection

New sockets circuits require an RCD now. Adding new sockets to existing sockets also requires an RCD. The RCD goes in the CU or fusebox - but many old fuseboxes can't accommodate an RCD. If that's the case, current regulations require you to fit a new CU.

Circuit joins

See main article Electrical connection

Cable connections in a socket circuit can be of 2 types:

  • accessible, meaning it can be reached readily using a tool
  • inaccessible, eg buried under tiling

Accessible joints are usually made using screw connections, either in the socket itself, or a junction box, or screwblock strip contained within an electrical backbox (for fire protection.)

Inaccessible joints may not use screw connections, as they can come loose in time. Permitted connection methods are:

Of these, crimping is by far the simplest and the least prone to problems in inexperienced hands.

The other approach to cable joins is to replace it with a new piece of cable that's long enough. Sometimes this is practical.

Junction boxes

See main article Electrical connection

Disused cables

Ensure disused cables are disconnected at both ends and, if they could become live inadvertently, link all the cores to earth at the supply/consumer unit end.

See also