radial cicuits

[Tony6]

Hi with regards from the following can you please tell me how to work out the maximum load for this circuit?


Radial circuits can therefore only serve a smaller area. Using 2.5mm2 cable combined with a 20amp fuse/MCB an area of 20 square metres (24 square yards) is permissible

 

[plugwash]

dunno where you read that but that area figure is bullshit

because it is virtually impossible to come up with accurate deversity figures for socket cuircuits the regs give the following guidelines

30/32A ring 100m^2
30/32A radial 75m^2 (no sprakys seem to really know why this is lower)
20A radial 50m^2

 

[phil_ballard]

'Diversity' gets mentioned a lot around here and I'm not convinced I understand it.

No, hang on, I AM convinced that I DON'T understand it.

Any chance of a potted definition/layman's guide?

MTIA

 

[ban-all-sheds]

http://www.tlc-direct.co.uk/Book/6.2.1.htm

 

[plugwash]

diversity comes in varoius forms at vaoirus levels

its always a bit crude but it bascially strms from the fact that designing for everything to be on full load at once would be prohibitive

to design like that would meen increasing the num ber of power stations about 100 times!

 

[phil_ballard]

All good stuff (thanks for the link, Ban) and that's kind of as I understood it; it's the areas in sq. metres that are doing for me. Where do they come in?

Sorry, I guess I'm being dense (not for the 1st time)

EDIT: Oh, maybe I see ..... the amount of floor area served with sockets by a cct will determine how many sockets are likely to be used concurrently? Maybe? ............

 

[plugwash]

pretty much it keeps rings to a managebale size in terms of load

the french regulate by socket count

the problem with this is this encourages the use of big extention leads because adding sockets properly involves extra cuircuits and hence is expensive

 

[ban-all-sheds]

Oh, maybe I see ..... the amount of floor area served with sockets by a cct will determine how many sockets are likely to be used concurrently? Maybe? ............

That's the theory, although where the 100, 75 and 50 sq m limits came from IHNFI.

 

[Tony6]

Thanks for the reply

Call me thick!

But what is the total load in kw for a radial circuit. Would i have to be calculate the appliances in kw before i could put on them on a radial circuit to reduce the chance of over loading .
if the appliances totalled to 90% of this figure and i put say a 2kw electric fire on the circuit would this lead to the chance of overloading / fire

Sorry if this sound dense to those who know...but im stressed with the french ****ing electrics

 

[ban-all-sheds]

The total load is the total load. It depends entirely on the total of the individual loads, and will be the same if those loads are on a ring or a radial.

 

[Tony6]

Thanks Again

To try and make some sense of this?

In france a radial circuit consists of 2,5mm twin and earth ,up to eight single sockets.protected by a 25amp circuit breaker 230v

this means the total load can be 5,7kw before the fuse pops?



should i use a 16 amp circuit breaker

any help would reduce the tablets???????

 

[ban-all-sheds]

To try and make some sense of this?

I'm trying, but I can't work out if you're trying to calculate the load on your circuit, or its capacity.

In france a radial circuit consists of 2,5mm twin and earth ,up to eight single sockets.protected by a 25amp circuit breaker 230v

Methinks you should take this topic to the Outside the UK forum - over here you don't get 25A breaker on 2.5mm radials. The highest that is listed in the OSG is 20A, and that's hedged about with a lot of restrictions on length and the type of protective device.

this means the total load can be 5,7kw before the fuse pops?

No - a 5.7kW load just takes you to the 25A nominal rating of the protective device. You've used both "fuse" and "breaker" here, so I don't know which is applicable to you, but they have different characteristics. For example a 25A Type B breaker will pass 28A indefinitely and will trip within 1 hour at 36.25A. If there was such a beast as a 25A semi-enclosed rewireable fuse it would pass 45A indefinitely, and 50A for an hour or so....

should i use a 16 amp circuit breaker

That would be much safer than 25A.

 

[Tony6]

thanks ban all sheds for your help