Ring main turns out to be a spur...

[Edmundo]

I recently added a fused switch and a double socket in my utility room as I am having a new boiler fitted there. I tapped in to the kitchen ring easily locating the ring going to the far end of my kitchen where a double socket is located.

It is now clear that it was not a ring main but a cable directly from the consumer unit (on a 16amp fuse) and a spur feeding 5 additional plugs (2 double 1 single). On the other side of the kitchen.

If you add all the above plugs up it's starting to sound a bit dangerous.....

To solve this problem I am going to feed a new cable from the last plug on the current spur back to the consumer unit and replace the 16amp fuse with a 32 amp one. Will this change my spur in to a ring main??? I am planning on doing the wiring myself but get an electritian to connect it up at the CU.

Is my plan a good one? any additional advice would be much appreciated.

 

[TheGaffersSon]

I recently added a fused switch and a double socket in my utility room as I am having a new boiler fitted there. I tapped in to the kitchen ring easily locating the ring going to the far end of my kitchen where a double socket is located.

It is now clear that it was not a ring main but a cable directly from the consumer unit (on a 16amp fuse) and a spur feeding 5 additional plugs (2 double 1 single). On the other side of the kitchen.

If you add all the above plugs up it's starting to sound a bit dangerous.....

To solve this problem I am going to feed a new cable from the last plug on the current spur back to the consumer unit and replace the 16amp fuse with a 32 amp one. Will this change my spur in to a ring main??? I am planning on doing the wiring myself but get an electritian to connect it up at the CU.

Is my plan a good one? any additional advice would be much appreciated.

It isn't a problem if the cable is 4mm. If the cable is 2.5mm then your plan sounds good mate. Except the cable ("Leg") you are introducing, to go back to the mains shouldn't come from a spur, it should come from a socket. Remember, all sockets should have two cables at them, except for the ones feeding the spur's - they have three. All spurs should have one cable from the ringmain (supply), and one cable going to whatever it's feeding (Load).

EDIT: I've just realised what you meant when you said come from the last plug on the spur. You mean come from the last socket don't you. A circuit like the one you have is called a radial, not a spur. (A spur is a connection unit fed off the sockets (1 cable). You're plan sounds spot on to me. Good luck mate.

 

[New2Game]

Keep to same cable size, i hope its at leasdt 2.5mm

 

[ban-all-sheds]

There is absolutely nothing wrong with a 2.5mm²/16A radial.

And this one has clearly been there for a while - any history of nuisance tripping?

 

[Pensdown]

As BAS has said, if the radial is not tripping now then adding a boiler will make very little difference and I ditto that a 16amp radial is fine.

You may get into deep water trying to turn it into a ring as you will need to inspect every socket to make sure only one has a single cable (the last one on the radial). You may find someone has added what they thought was a spur which will also only have one cable but it will not be the last socket on the radial.

Personally if it's not causing you a problem I would leave it alone.

 

[TheGaffersSon]

Personally if it's not causing you a problem I would leave it alone.

Agreed.

 

[Edmundo]

Ok. the radial circuit has been fine and I have had no problems with it tripping out etc...

When I put in the additional switch for my new boiler I also added a single socket and a double socket.

So running from my 16amp radial circuit is: 4 double sockets, 2 single sockets and a 13amp switch (for boiler). Is this safe? what are
the maximum number of sockets allowed on a radial circuit?

- The cable is 2.5mm and my kitchen is 2meters by 3.5meters and about 6 meters away from my consumer unit. Can I upgrade by 16amp mcb to 20amp?

 

[ban-all-sheds]

So running from my 16amp radial circuit is: 4 double sockets, 2 single sockets and a 13amp switch (for boiler). Is this safe?

Yes - no matter how many sockets you have you cannot overload the cable because of the 16A breaker

what are the maximum number of sockets allowed on a radial circuit?

There is no limit.

- The cable is 2.5mm and my kitchen is 2meters by 3.5meters and about 6 meters away from my consumer unit. Can I upgrade by 16amp mcb to 20amp?

Yes. But why, if the 16A never trips?

 

[TheGaffersSon]

Add the extra to the ringmain, and if it keeps tripping then change the breaker. Its good you are precautios but it's unnecessary at this stage.

 

[securespark]

I'd up it to 20A, though. And I guess that this 20A 2.5 radial does not serve more than 50sqm??

 

[Steve]

@ the OP, you have 2.5mm cable, this is rated to about 27 amps optimally. You have it on a 16 amp MCB.

What part of this do you think is dangerous? The MCB is the protective device, it is providing plenty of protection to the circuit and the cable. It is perfectly safe.

No matter how much load you put on this circuit, it is safe. If its too much, the MCB will trip. If its not tripped yet, it is not being overloaded. Yes, 16A is a little low for a kitchen, but its causing you no problems. Leave it alone. If it does start tripping in future, upgrade it to a 20A radial.