Radials Circuit Designing

[Snapester]

Hi guys, doing a rewire in which i plan to do the circuits in 4mm as radials, one down one up and kitchen. When designing how can i work out the loading along the circuit? Also how can you work out the loading on a lighting circuit radial as the load will be split along the length so the furthest point may only be loaded at 100w?

Hope this makes sense.
Cheers

 

[Engineer54]

2 sockets in a Kitchen?? haha!!! Not always possible to install a staggered ring??
Enough said i think!!!

 

[Snapester]

Agreed.:24:

 

[T&Earth]

Hi Ackbarthestar

Many thanks for taking the time to reply to my question.

Cheers
T&E

There are various ways of writing it, I've chosen one possible method.

The key is to recognize that at the first fitting the maximum current will be drawn but at the shortest distance.
At the last fitting the minimum current will be drawn but at the longest length.

1/ Draw the circuit for the number outlets to be calculated
2/ At each outlet the current diminishes. so calculate the current in that section of the cable leading up to each outlet.
3/ Now for each section of cable calculate the volt drop
4/ add the different volt drops for each section

 

[Brightspark2]

, which will virtually nullify any chance of future spurred outlets without the use of a JB!!

Why?...

 

[Engineer54]

Why?...

Because BS UK accessories have cable termination facility to max 10mm, so 2 X 4mm + a 2.5mm is over the recommended cable fill. Sure it can be done, but it's going to be a real pig and the terminal screws are going to be at it's full reach (exposed). Trying to get another 4mm in there (12mm) is as far as i'm concerned a No-No!!

 

[GLENNSPARK]

4mm Radials are great the stranded cable make it slightly more flexible than 2.5, but beware i have installed a few in the past and with a 1.5 cpc in the 4.0 T+E the max earth fault loop impedance creeps up on you with any length. make sure you use B type or you will have problems, I have tried to Buy 4.0 T+E with a 2.5 CPC but no luck.
I would however look at a ring circuit for the Kitchen as the complexity of the circuit with spurs for appliances etc, can get a bit tight with 3 x 4.0 T+E's at a switched spur??

this is it with 4mm T&E.....gotta watch the Zs.....

 

[Brightspark2]

Because BS UK accessories have cable termination facility to max 10mm, so 2 X 4mm + a 2.5mm is over the recommended cable fill. Sure it can be done, but it's going to be a real pig and the terminal screws are going to be at it's full reach (exposed). Trying to get another 4mm in there (12mm) is as far as i'm concerned a No-No!!

Of course yeh, very true...