Help with diagram please

[Donkeydaz]

Hey guys, i am a 3rd year apprentice doing an assignment from home, im drawing a ring circuit with socket and spur, trying to figure out how to draw the spur, can someone help please?

This is what i think it should be, with supply going in and out, nothing on the load side is drawn in the picture.

http://imageshack.us/photo/my-images/856/spur.png/

Cheers guys​

 

[gutterball]

ImageShack® - Online Photo and Video Hosting try that

 

[Donkeydaz]

Looking at that it looks like a socket ring with a spur, spured off the ring? correct? this is not what i am after.

im connecting 2 sockets and a spur in 1 complete ring, spur in middle and socket either side, i know how to do the sockets ofc, just iffy if the spur is correct that i have drawn.

 

[Knobhead]

Try turning the switch upside down. The fuse should be on the output side of the switch.
Otherwise OK.

 

[Donkeydaz]

thanks mate, i assume you mean like this?


Uploaded with ImageShack.us

 

[Donkeydaz]

thank you mate, i assume u mean like this?

ImageShack® - Online Photo and Video Hosting

 

[geoffa]

A spur means a radial branch connected to a ring circuit. What you've shown in your original diagram is a fused switched outlet (commonly referred to as a fused spur, or a spur), connected into the ring circuit as you wanted to show. so you've drawn what you wanted

 

[Donkeydaz]

yea a im trying to draw a fused spur on a circuit, just wanted to make sure what i had drawn was correct before i draw it into my assignment

 

[ian.settle1]

A spur means a radial branch connected to a ring circuit. What you've shown in your original diagram is a fused switched outlet (commonly referred to as a fused spur, or a spur), connected into the ring circuit as you wanted to show. so you've drawn what you wanted

It's also referred to as a Fused Connection Unit (FCU)

 

[geoffa]

one thing to consider before you stick with your idea of having fused switched outlet as part of the ring main which is perfectly acceptable is this: the reason that these outlets or FCU's are so commonly referred to as spurs is because they are most commonly used at the end of a spur from a ring main.
The reason spurs are used with ring mains is to minimize the amount of cable used and the incurring cost of the insatllation.
A ring main most commonly requires 2.5mm T&E (6242Y is the cable code) beginning at the circuit protection device to and from each socket with a return cable back to the circuit protection device. As 2.5mm T&E is only rated at 27A (this varies depending on how the cable is routed through the building), this is why a ring is used so that current can be drawn from both sides of the ring. (However, circuit design still needs to be considered so that the designer eliminates the potential for drawing in excess of the max safe current carrying capacity through the 2.5mm T&E). A spur taken from a ring main circuit is only 1 2.5mm T&E cable which can safely supply 2 outlets whether they be a switched fused outlet (max of 13A load possible) or a single 13A socket. 2 outlets have a maximum potential to deliver 26A load so within the current carrying capacity of the cable's 27A.
Therefore it may be better for your assignment to show the fused switched outlet or FCU connected to a spur from the ring main to demonstarte cost and labour saving in your design. You're likely to extra mark/s for it.


EDIT:
gutterball's diagram illustrates this alternative

 

[Donkeydaz]

thanks for your reply, and i understand your reasoning fully, but the way we have done it is the way it has to be done at college working from printer drawings so it has to be done this way

Radial wired in 2.5mm singles (3 sockets)
Ring final circuit wired in 2.5 mm T+E (2 sockets and a spur)
Lighting Circuit with 2 way switch and 2 Lamps wired in 1.5mm singles.

 

[giio]

A spur taken from a ring main circuit is only 1 2.5mm T&E cable which can safely supply 2 outlets whether they be a switched fused outlet (max of 13A load possible) or a single 13A socket. 2 outlets have a maximum potential to deliver 26A load so within the current carrying capacity of the cable's 27A.
Therefore it may be better for your assignment to show the fused switched outlet or FCU connected to a spur from the ring main to demonstarte cost and labour saving in your design. You're likely to extra mark/s for it.

I think a dual socket in a domestic property is acceptable on a spur, using your analogy a 2.5mm ring circuit using 8 double sockets has the potential to draw 208 amps, the reason we get away with the 2.5 ring circuit in domestic situations is that is is highly unlikely that this will ever occur,unless somebody is growing dodgy plants that make you happy.
We were called to a Pickfords depot a few years ago and the 2.5 /30amp ring circuits had burned out in their offices,the reason was the boiler had failed and as the weather was cold the managers bought in a load of 3 kw convector heaters and plugged them in all over the place,they thought the smell of burning was because the heaters were new. so beware even the humble office with just a few pc,s can become a major problem quite innocently

sorry geoffa misread you a bit there on re reading, I'll leave my post on anyway it might be of interest and also shows the wisdom of the "measure twice cut once" saying