Hi I'm new here! Have a question on Radial & Ring circuits

[Velascas]

I am a DIY and working on an extension on my home. I found out that one area of my house is on a 4mm radial for sockets on a 32amp mcb which I know is fine.
Now the question is
Can I safely continue wiring 4mm radial?
Total length from distribution to last socket will be around 60metres with 12 points.
Things permanently plugged in are:
80L Water heater - ~2000w
Washing machine - ~500w
Bench Freezer - ~500w
Underfloor heating for small shower room - ~180w
Treadmill - ??
32" tv - ??

 

[Pete999]

Not essential as others will mention, but if you are rewiring, it would be advantageous to put the water heater on it's own breaker.

 

[Velascas]

Not essential as others will mention, but if you are rewiring, it would be advantageous to put the water heater on it's own breaker.

Hi Pete
Thanks for reply but I think I haven't made myself clear. I am not rewiring and it is quite difficult/messy to rewire from the distribution box.
My question was if I have 5 points on a 4mm radial and I open the 5th and connect another 6 points with the loads and length mentioned above always with 4mm, is it ok?
Optional I could go from 5 to 6-7-8-9-10-11 and back to 5 creating a ring on top of 5 in 2.5mm. Would this be stupid?

 

[Pete999]

If you did what you suggested then you would have what, is commonly called a lollipop circuit i,e, a ring fed from a 4mm supply not ideal and non compliant with BS7671, Don't wish to be rude but you would be better off getting someone qualified in to do the work.

 

[telectrix]

OP is in malta pete. don't think 7671 applies.

 

[Pete999]

OP is in malta pete. don't think 7671 applies.

Yep realised that after I posted, thought someone would come back and remind me

 

[dingledong]

Yes your electrical regulations could be different to ours in England best to get a local electrician in

 

[Velascas]

I am not really concerned about regulations, it's safety and theory. Just to put you in the picture I have been working on the electrics at my place, my brother's, my sister's and at my dad's (who was a qualified and licensed electrician but is now 78) for years but always wired ring circuits for socket outlets. I asked the question because some pro decided to do a radial and I need to add more sockets onto it. If I were rewiring I would simply rewire a radial. I don't want to sound rude but does anybody know how to answer the question asked? I can't find an answer on books!

 

[Richard Burns]

A 32A radial circuit in 4mm²/1.5mm² twin and earth cable can be extended by adding additional sockets on to the end (or from any point in the circuit (though it would be tight for the cables)), as you propose, however in the UK extending the circuit beyond 33m in total length would contravene the volt drop limitations of the circuit and extending it beyond 31m would compromise the earth fault loop impedance values required for disconnection within 0.4s (assuming the 32A device is a type B MCB)

 

[dingledong]

Not concerned about regs not an electrician but has rewired 3 or 4 properties but is still not sure what he is doing
Not for me

 

[Velascas]

Not concerned about regs not an electrician but has rewired 3 or 4 properties but is still not sure what he is doing
Not for me

What I meant about regulations is that ours might be different than yours. I just wanted a simple question answered "Can I safely continue wiring 4mm radial?" or is it too long. And I never said I rewired 4 properties, I do the bits and pieces my family needs with the help of a 78 year old retired electrician (my dad).

 

[telectrix]

you can safely extend the radial in 4mm. assuming a design current of 30A, you max. length for the circuit is 32m. anything over and you will be having problems with volt drop. a lower value of current will allow you a bit more latitude with the length,

 

[Velascas]

you can safely extend the radial in 4mm. assuming a design current of 30A, you max. length for the circuit is 32m. anything over and you will be having problems with volt drop. a lower value of current will allow you a bit more latitude with the length,

So since my last socket is about 50m length of wire away from distribution what are my options? I thought of rewiring a 2.5mm ring even though it is not that easy given the installation is in conduit pipes plastered in a brick wall.

 

[Richard Burns]

Make it into a badly designed 4mm² ring by taking a 4mm² cable back from the end socket to the Consumer unti, this will unbalance the ring but the protective device at 32A and the current carrying capacity of the cable means the cables will not be overloaded.
Replacing the 4mm² cable with a 6mm² throughout the circuit would allow a length of 49m,but be a major work to do.