Hi!
Upstairs, we seem to have a radial circuit.
It is protected with a 20A MCB and uses 2.5 cable.
Is there any problem with simply adding another socket on the end of it?
Sparks...
- posted
20 years ago
Radial Circuits
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- posted
20 years ago
No, provided it won't be extending the floor area covered by the sockets. You can spur off the circuit wherever it is convenient, not just at the end of a long snake of sockets. However, practical considerations make it difficult to spur off a socket that already has 3 cables.
Christian.
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- posted
20 years ago
Ok, thanks!
I take it you can't subsequently spur off a mid-point spur?
Sparks...
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- posted
20 years ago
Doubtful. There are possibilities why it could not be feasible but it is more than likely to be fine, assuming you are in an average sized house that is. Are you putting the socket in another area or in a room already covered by the existing circuit? Reason being a radial should not cover a floor area of more than 20sqm if it is on a 20A MCB in 2.5mm cable.
SJW A.C.S. Ltd.
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- posted
20 years ago
Spur to your heart's content, provided the conductors will fit in the holes. Stick in junction boxes if you like, or don't, it's entirely up to you.
Christian.
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- posted
20 years ago
On a radial circuit, you can spur off a spur off a spur as often as you like.
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- posted
20 years ago
So I can just slap a junction box in at any point and connect another 10,000 sockets (hypothetically!)
Sparks...
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- posted
20 years ago
Ok...
My house is a bungalow... The loft has been converted into two rooms.
There is still a passage way around the perimeter of these rooms We use it so store crap (surprisingly!)
The way into this space is via a small door (you have to duck to go through it)
I want to install a socket in this space, for a PC server
The new socket will be in arms length of an existing one the other side of the door
The whole top floor, including the loft space is under 20x20m
Sparks...
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- posted
20 years ago
Yes*, but you are limited in the floor area that you serve. The justification is that they would prefer you to have lots of sockets so that your computer/TV/DVD etc. can have a proper safe socket instead of being plugging into an adapter. However, the floor space requirement means that you are unlikely to plug in multiple fan heaters into the circuit when the boiler goes Pete Tong.
Obviously, these maximum area rules apply only when predicted loads don't override the requirement. There's no use saying that a 20A radial is fine for a large kitchen, because it is obvious that there will be a washing machine/tumble dryer/dishwasher/microwave/kettle/iron/dual fuel cooker etc.
Christian.
- Well, actually no.
If 20m2 is allowed for this radial (as the other poster suggested, but I can't remember the figure myself), then assuming a 5m x 4m x 2.4m room, and allowing approximately 20cm x 10cm for the box, you can only fit around 2200 double sockets on the wallspace. Even a few stud partitions and ceiling mounting will be unable to fit 10,000 sockets.
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- posted
20 years ago
When you say 20x20m do you mean under 20 square metres or under 400 square metres? Anyway, I think for what you want to do that will be fine.
SJW A.C.S. Ltd.
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- posted
20 years ago
I think it might be 50m2, come to think of it. 20m2 sounds too small to me.
Christian.
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- posted
20 years ago
50m2 with 4mm cable on a 30A MCB 20m2 with 2.5mm cable on a 20A MCB
SJW A.C.S. Ltd.
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- posted
20 years ago
Any topology you like.
.andy
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- posted
20 years ago
Fused spurs are unlimited but as far as i am aware non fused spurs for radial and rings should not exceed number of switched outlets on the cct. And I would say the OP is not spurring off but extending the circuit
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- posted
20 years ago
I thought it was square meters, not cubic meters?!
Sparks...
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- posted
20 years ago
A quick browse on the Internet shows that your figures:
And the alternative figures:
30/32A MCB ring = 100m2 30/32A MCB radial = 75m2 20A MCB radial = 50m2abound in equal measure. I suspect there has been a change. I wonder which is the more recent?
Christian.
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- posted
20 years ago
This rule of thumb only applied to rings, not radials. It has now been reworded that the likely current draw of the circuit should be ascertained to ensure that similar currents flow in both legs. (i.e. you shouldn't put all the spurs and high current devices on one side of the ring). The spur rule was designed to help do this, but was not very effective.
Christian.
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- posted
20 years ago
Thought what was square metres? I took 20x20m to mean an area 20m along one side by 20m along an adjecent side. Equalling 400 square metres. For cubic capacity you would have to include the height, I don't know how high your ceilings are so can't calculate this. If your room is 2m wide by 10m long this would equal 20 square metres.
SJW A.C.S. Ltd.
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- posted
20 years ago
I have always erred on the side of safety, personally though I try to keep 2.5mm radials on a 16A, 4mm radials on a 20A. At a push I'll put a 20A radial in 2.5mm if it's just feeding a couple of sockets. I would have to go and dig the regs out to see what it actually is but as I am always under with radials I don't concern myself too much, looking on the interweb the majority go with my way, but whether that is the most current I don't know.
SJW A.C.S. Ltd.
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- posted
20 years ago
I can see your point on load sharing and as you said have as many outlets as you like as long as protection is ok but still cant find it in OSG , but i will not lose any sleep over it !