Can I...

[clodhopper]

...spur off a ring main with a blue 16A socket?

 

[ban-all-sheds]

Using a 13A FCU yes, but not unfused, as there is no downstream protection provided by a fused plug in that case, to provide overload protection for the spur cable.

Or maybe it would be OK if you used 4mm²? An interesting one.

 

[toasty]

Our comms rooms here are wired using 16amp blue commando sockets straight into CUs with 32A breakers using 4mm SWA. I always thought that was odd, but then they all power 15way distrubution strips which have a 16A mcb in them. I always assumed it was to avoid nusence tripping (they power servers and the like)

Personally I would say you shouldn't do it, it doesn't seem right, but then neither does the fact that you can't plug 2 13amp devices into a double socket.

Don't forget also that the blue sockets aren't shuttered, so be careful if you have small children around who might poke things in them - the 32A one in my garage is high up to avoid this.

-Dan

 

[Pensdown]

...spur off a ring main with a blue 16A socket?

If you want to use a 16amp plug you have a few options. You could feed it via a 13amp FCU. You could also feed it via a small 2 module CCU and fit a 16amp MCB or an RCBO.

I'm not sure what you intend to use the plug for but if it's for a fixed load I would not recommend that you spur it off the ring. A dedicated 16amp radial is the correct method of installation.

Could you post a few more details of your project as that would help us determine the best solution.

Or maybe it would be OK if you used 4mm²? An interesting one

He could spur directly off the ring using 4mm cable but he would need to use a 32amp socket and not a 16amp one.

Our comms rooms here are wired using 16amp blue commando sockets straight into CUs with 32A breakers using 4mm SWA

They should be fed via a 16amp breaker because the plugs and sockets are only rated at 16amps

 

[Spark123]

I believe the 16A ceeform sockets are allowed to be fused up to but not exceeding 20A.

 

[Pensdown]

I think you are right, 20amps max

 

[Lectrician]

I believe the 16A ceeform sockets are allowed to be fused up to but not exceeding 20A.

Thats correct - they can be installed on a 20amp radial circuit.

Not un-common to see them fed individually from a CU on C16 breakers, or 2 or 3 on a C20. Never on a C32.

 

[clodhopper]

This is a job I need to do at th factory where I work. The ring is wired using 2.5mm SWA and has 3 socket outlets. One of the m/c's plugged into one socket is drawing 13.4A and this was picked up on a PAT as overloading the plugtop. My intention is to spur off the ring at the socket with a 16A socket as this is by far the easiest solution. I cant find any reg which stops me doing this though as some of you have said, it doesnt seem right.

 

[RMS]

I'm under the impression that spurring off a socket should not really exceed 13amp. ie. the rating of the socket.

 

[clodhopper]

I'm under the impression that spurring off a socket should not really exceed 13amp. ie. the rating of the socket.

That can't be right. The point in a circuit where a connection is made can't be relevant can it? The current flowing through the 13A socket will be 0A only the 16A socket and the ring will be taking the load.

 

[Pensdown]

You could split the ring into 2no 20amp radials. One for the sockets and one for the 16amp plug. Are there any spare ways at the dis board?

 

[RMS]

I'm under the impression that spurring off a socket should not really exceed 13amp. ie. the rating of the socket.

That can't be right. The point in a circuit where a connection is made can't be relevant can it? The current flowing through the 13A socket will be 0A only the 16A socket and the ring will be taking the load.

The point where you connect the load in a ring final circuit can be relevant depending on the size of the load.

If an electrical load draws a current of 13amps from the supply then the full 13amp load will be drawn through the point of load. Obviously resistance and temperature can effect the current.

 

[clodhopper]

I'm under the impression that spurring off a socket should not really exceed 13amp. ie. the rating of the socket.

That can't be right. The point in a circuit where a connection is made can't be relevant can it? The current flowing through the 13A socket will be 0A only the 16A socket and the ring will be taking the load.

The point where you connect the load in a ring final circuit can be relevant depending on the size of the load.

If an electrical load draws a current of 13amps from the supply then the full 13amp load will be drawn through the point of load. Obviously resistance and temperature can effect the current.

but wont it do that irrespective of where it's connected ie socket terminations, jb a couple of inches away?

 

[Lectrician]

If it's only got 3 sockets, I can't see the circuit being very long????

And therefore, probably very easy to run a seperate circuit????

Pat testing recorded 13.4amp?? LOL.

Lengthen the appliance flex, that should loose the .4 of an amp

Has the appliance got a moulded lead, or spec plate with loading? If i does, I would start with a call to the manufacturer........

 

[RMS]

Clodhopper,

Yes the load will be approximately the same regardless of it's position. The point i was making is that care must be taken by the designer as to where you connect load with a ring final circuit by means of balancing the load between the two legs.

Obviously in your case this can be seen as negligible as the load is only the sum of 13amps. This was just an answer to your previous post about the point of connection in a ring final circuit having no relevance.