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.
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.
* 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.
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 = 50m2
abound in equal measure. I suspect there has been a change. I wonder which
is the more recent?
On Thu, 29 Jan 2004 17:46:23 -0000, "Christian McArdle"
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.
The larger areas (50 & 75m^2) are the more recent. The change was made in
1998, when the yellow cover OSG was published.
- these figures are guidance, not regulations, and must be used
with knowledge of the loads likely to be connected;
- sticking to these figures does not exempt you from the need to
check compliance for voltage drop, cable ratings (installation
conditions, ambient temperature & grouping factors) and earth
fault loop impedance.
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
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.
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.
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