Spur Question(another)

[steveo44]

Reading through past threads i see my question is a common one but i'm still not sure of the answer.

Question: I have a ring main circuit that has a spur wired from it that has a double socket. I would like to add a switched fuse spur after the double socket, is this ok?

 

[flameport]

No it is not.

The options are either put the fused spur first, then socket(s) and whatever else after that which will limit the total load on the spur to 13A
or
connect the fused spur at another point on the ring
or
dispose of the ring and rewire the house with radials, so you can attach extra sockets anywhere you like.

 

[steveo44]

connect the fused spur at another point on the ring
.

Thanks for the swift reply flameport.

I thought you could only spur off from a ring once?

The unswitched spur will be fused at 3amp, does this make any difference?

 

[electronicsuk]

I thought you could only spur off from a ring once?

You can spur from any accessory that's part of a ring, or a JB on the ring, as many times as you like up to the number of available accessories/JBs to spur from. What you can't do is take a spur from an accessory that's already a spur.

The unswitched spur will be fused at 3amp, does this make any difference?

None whatsoever.

 

[steveo44]

Good info thank you.

I am an Alarm Installer and 18 months ago i attended a course for "Inspection, Testing and Certification of Minor Works". The course was more about the instructors horror stories from the past with 30mins practical at the end. My company have now asked me to fit a fused spur for the first time next week and any help/tips would be much appreciated. One other question: would i be ok to connect to a ring main circuit at the consumer unit if only two live wires are in the breaker?

 

[electronicsuk]

One other question: would i be ok to connect to a ring main circuit at the consumer unit if only two live wires are in the breaker?

Yes, you can do that. Some might (wrongly) frown upon it by looking at it in a similar light to a 2.5mm radial backed by a 32A breaker, but the maximum load is limited by the fact that there's only one accessory at the end of the spur.

 

[steveo44]

No it is not.

The options are either put the fused spur first, then socket(s) and whatever else after that which will limit the total load on the spur to 13A
or
connect the fused spur at another point on the ring
or
dispose of the ring and rewire the house with radials, so you can attach extra sockets anywhere you like.

What difference would fitting the spur as the first device make please?

With a radial circuit can you spur off as you wish or must all devices be daisy chained?

 

[electronicsuk]

No it is not.

The options are either put the fused spur first, then socket(s) and whatever else after that which will limit the total load on the spur to 13A
or
connect the fused spur at another point on the ring
or
dispose of the ring and rewire the house with radials, so you can attach extra sockets anywhere you like.

What difference would fitting the spur as the first device make please?

Because if everything that follows is on the load side of the FCU, then the spur will be protected by the 13A fuse in the FCU, thus preventing overload of the spur cable.

With a radial circuit can you spur off as you wish or must all devices be daisy chained?

You can wire it in more or less any configuration you like, although it wouldn't really be a 'spur' as such, just another part of the circuit.

 

[steveo44]

Because if everything that follows is on the load side of the FCU, then the spur will be protected by the 13A fuse in the FCU, thus preventing overload of the spur cable.

But what if the FCU has a 3amp fuse?

 

[electronicsuk]

Because if everything that follows is on the load side of the FCU, then the spur will be protected by the 13A fuse in the FCU, thus preventing overload of the spur cable.

But what if the FCU has a 3amp fuse?

Then everything after the FCU is of course limited to 3A. There is nothing wrong with a 13A FCUs load terminals being used to supply an FCU fused at 3A plus whatever other accessories you want to run from that branch circuit.

 

[sparkwright]

You would remove the existing double socket that is a spur from somewhere.

You would change it for a 13 amp fused spur unit.

Then, from the load side terminals, you can (in any order) connect the double socket and your 3 amp fused spur which will supply your alarm.

The 13 amp fused spur will protect the double socket and alarm spur unit.

You can connect as many sockets as you like from the load side of the 13 amp fused spur unit, but obviously it wouldn't be sensible to fit too many as you don't want the load to exceed 13 amp.

 

[Spark123]

I am an Alarm Installer and 18 months ago i attended a course for "Inspection, Testing and Certification of Minor Works".

I imagine the course is aimed at people who already know how to carry out the minor works to BS7671 then IT&C it afterwards.

My company have now asked me to fit a fused spur for the first time next week and any help/tips would be much appreciated.

Your company needs to ensure you are trained on electrical installation work if they expect you to carry it out, also knowledge of the current edition of the wiring regulations is essential as that is what you will be carrying out the work followed by Inspection, Testing and Certification to.

 

[ban-all-sheds]

And I would suggest that if you find yourself having to ask how to do your job on a DIY forum that your company did not train you properly.

 

[steveo44]

And I would suggest that if you find yourself having to ask how to do your job on a DIY forum that your company did not train you properly.

aint that the truth


What if the layout was: fcu then a single socket. maximum load = 26Amps. The only problem i can see is if the circuit was added to later. Would this layout be acceptable?

 

[ban-all-sheds]

18 months on, and you've not learned anything.

You clearly have no interest in electrical work, which is fine - I have no interest in line dancing. But it does mean that you shouldn't be doing it, because given your lack of interest you're never going to do it properly.