radial or ring circuit

[paul341]

hi can any one help i have nearly finished my domestic installer course , i am planing on putting 2 sockets on a radial circuit i have disided to use a 20a rcbo and 2.5mm t+e fan lights and radio of the shower unit run of a 12v selv transformer wich i am going to run off a fcu 13a then continue to the shower pump wich is 1.5a pump runing of a 5a fcu have worked calculations out and spoken to paul m thank you for your guidance regards paul

 

[Paul.M]

Paul, use this has part of your training. What load will all the fittings take? Work out the cable and rcbo size and then post up your findings for us to check over. It's a great opportunity for you to put your classroom work into practice.

 

[paul341]

thanks paul i will work on this over the week end , i have just passed 2330 201,202,203,204 and pat testing this week and got the part p full scope and 2382 10 17th edition next week

 

[nickblake]

16 amp RCBO on 2.5mm 20 max and dual patress , wire into 2 fused spur's fan at 2 amps and the pump at 3 amps , just to advise you that this type of work is notifiable under part P of the building regulations as its a special location, oh thats asuming your shower pump is just a pump and no heating elements

 

[Deleted member 26818]

If you intend designing and installing a Radial, it might be prudent to have a look at the examples in Appendix 15 of BS7671.
Especially when considering the rating of the CPD and the CSA of the conductors.

 

[SMB]

hi can any one help i have nearly finished my domestic installer course , i am planing on putting 2 sockets on a radial circuit to feed my shower pump in my airing cupboard and one out side the bathroom in a cupboard for the power suply to my shower fan and lighting witch runs off a transformer i am thinking of using a 32a rcbo in the cu and using 2.5 twin and earth is this suitable or would it be better on a ring circuit regards paul

Hi Paul341.
You can not fuse a 2.5mm fed circuit at 32amps mate. A ring yes, a radial no.

Without looking I think the maximum current carrying capacity of 2.5mm is 27amps.

Regards.

 

[Paul.M]

Let him work this one out be himself and then he can learn the process of installing a new circuit for the first time. Of course checking his info first with the forum to make sure everything is correct and safe. Pauls on a distant learning course so this will be a good exercise for him with the backing from us. Good luck mate and get back to us with your findings/installation plan.

 

[malcolmsanford]

hi can any one help i have nearly finished my domestic installer course , i am planing on putting 2 sockets on a radial circuit to feed my shower pump in my airing cupboard and one out side the bathroom in a cupboard for the power suply to my shower fan and lighting witch runs off a transformer i am thinking of using a 32a rcbo in the cu and using 2.5 twin and earth is this suitable or would it be better on a ring circuit regards paul

thanks paul i will work on this over the week end , i have just passed 2330 201,202,203,204 and pat testing this week and got the part p full scope and 2382 10 17th edition next week

Paul please don't take this in a negative way but this could be a customers house your working in and you don't really have much of a concept about what is very basic circuit design.

Are you sure you are even remotely ready to tackle any electrical work without supervision. The forum is a great place to get ideas on things, even some of the really experienced hands on here come up against something where it is good to bounce ideas off of, but I really would expect a 1st year apprentice to realise you can't wire a 2.5mm^ radial protected by a 32amp RCBO. Do you have any concepts or heard of A1 ring final circuits or A2-A3 Radial circuits?

 

[paul341]

hi paul well after a nites sleep it better to work things out:as i have just noticed the print error in appendix 15 wich it is saying a radial circuit should start and finish at the circuit board. witch is incorect i calculated the maximum demand the pump is fused at 1.5a so it will have a 3 amp fuse in the plug and the selv transformer is fuse rating is 1300mA so this is a 13 amp fuse in plug so calculating the fuse rating it works out to 16 amp so there for i would use a 20a rcbo with 2.5mm t+e regards paul

 

[mogga]

I personaly find the question and quote that OP is PartP Full scope rather scarey as malcom says 1st year apprentice stuff
as Paul says work with your books use max demand ect get an answer and post it for opinions

 

[malcolmsanford]

hi paul well after a nites sleep it better to work things out:as i have just noticed the print error in appendix 15 wich it is saying a radial circuit should start and finish at the circuit board. witch is incorect i calculated the maximum demand the pump is fused at 1.5a so it will have a 3 amp fuse in the plug and the selv transformer is fuse rating is 1300mA so this is a 13 amp fuse in plug so calculating the fuse rating it works out to 16 amp so there for i would use a 20a rcbo with 2.5mm t+e regards paul

This is the advice I can give you get an electrician in if you believe really what you wrote here as you are seriously out of your depth.

If this is the bathroom fan your talking about then the manufacters instructions will tell you what to do ......so please do that.

 

[Deleted member 26818]

hi paul well after a nites sleep it better to work things out:as i have just noticed the print error in appendix 15 wich it is saying a radial circuit should start and finish at the circuit board. witch is incorect i calculated the maximum demand the pump is fused at 1.5a so it will have a 3 amp fuse in the plug and the selv transformer is fuse rating is 1300mA so this is a 13 amp fuse in plug so calculating the fuse rating it works out to 16 amp so there for i would use a 20a rcbo with 2.5mm t+e regards paul

Download the corrigenda from the IET's website for the corrected version.

 

[solo2771]

Hi paul, as there is a shower involved this would be notifiable and as it is not an emergency you would have to notify before you start and after the circuit would have to be tested by a competent person and notified to building control. May I ask are you on one of these 4 week become an electrician course?
Paul

 

[SimpleSimon]

hi paul well after a nites sleep it better to work things out:as i have just noticed the print error in appendix 15 wich it is saying a radial circuit should start and finish at the circuit board. witch is incorect i calculated the maximum demand the pump is fused at 1.5a so it will have a 3 amp fuse in the plug and the selv transformer is fuse rating is 1300mA so this is a 13 amp fuse in plug so calculating the fuse rating it works out to 16 amp so there for i would use a 20a rcbo with 2.5mm t+e regards paul

Hi Paul.
Are you putting the fan and the pump on plug in sockets because they have plugs incorporated in them or FCU's?

 

[Paul.M]

I spoke with Paul yesterday just to clarify what he is putting in as the op was clear enough to give full correct advice. What he has bought is one of those all in one units that is separate to the shower that has a built in radio, lights and fan that runs from a transformer. 2nd part is a water pump. He has now looked at his options and knows that it will be best on 2 fcu for local isolation and he has also done his cable and protection cals again. He is now on the right track. Paul is doing one of these distant leaning programs due to working full time (not in the industry) and also looking after his family so to say. This is why I've spent a bit of time on this with him. Nothing wrong with anybody trying to better themselves but some guidance is needed and I'm glad he asked for help instead of just going ahead and having a go.