Radial or ring circuit

[thewatcher87]

Hi all.

First post here at DIYnot. I live in a mobile home and am putting another mobile home on in a sort of L-shape to give me an extra 4 rooms.

I have ripped the ceiling down and have installed new insulation and have wired the lighting in.

I am in the middle of partitioning off the rooms. Starting on Tuesday but am now back to work for a few days so can't get much done.

I am undecided as to what type of circuit to put in. I intend on putting two power circuits in (one for each half of the mobile).

Should I put radial or ring circuits in. In one of the halves I plan on putting the master bedroom, a computer room/study and a dining room. On the other half another bedroom and a hallway.

For the time being I plan on using electric heaters which I know will be fond of electric.

What type of circuit would you recommend I use? I know radial will be easier so thought I'd ask here. If I have to use ring it's not a problem just got a bit more wire to use.

The size of the mobile is 30ftx20ft.

Any help and replies are appreciated.

 

[ban-all-sheds]

This is a genuine reply, not a sarky one:

The best approach is the one that you feel is best for you, given your understanding of the advantages and disadvantages of each (which includes having an informed and educated view on what are advantages and disadvantages), and given your knowledge of layout and the way you'll use the circuits.

Not being funny, but you must be able to do the design.

 

[PrenticeBoyofDerry]

It's your choice, either or!
Some will side with Radials some will side with Ring Finals.
Work out your loads on each circuit.
Get your fuse rating right for that and the correct cable size.
I prefer rads as they are slightly easier to route.

 

[thewatcher87]

The radial will be easier as I can just run from one room to the next. If it was a ring it'll mean I'll have to double the cable on itself to the CU as the mobile is in two 30ftx10ft halves. What diameter of cable should I use?

What sort of load can I put on radial circuits and how many sockets is my limit?

Sorry for all the questions.

 

[ban-all-sheds]

What diameter of cable should I use?

http://www.tlc-direct.co.uk/Technical/Charts/VoltageDrop.html

What sort of load can I put on radial circuits

//www.diynot.com/wiki/electrics:mcbtocable

and how many sockets is my limit?

Only the practical ones imposed by wall space and circuit length.

Sorry for all the questions.

• For a circuit to supply a given load, how would you go about deciding what cable and protective device to use?
  
  
• Do you know which circuits can be ring finals and which cannot, and what the advantages and disadvantages of each are?
  
  
• How do you calculate maximum demand and how can diversity be used?
  
  
• Do you understand how the way in which you install cables affects how much current they can carry?
  
  
• What are the rules concerning cables concealed in walls, partitions and under floors?
  
  
• Where cables need to be joined, how should this be done / not be done and in what circumstances are different methods acceptable?
  
  
• Which circuits should be RCD protected?
  
  
• Do you know what tests you would carry out on the new circuits - what sequence you'd do them in and at what point you would energise them, and for each test do you know what is being measured, why it is important, how you would carry out the test, and with what equipment, and what sort of results you would expect to get if everything was OK?

The thing is, the work you plan to do is not trivial, and I can assure you that it involves knowing far more than you think it does.

Asking questions here can be a useful part of a learning process, but they are not a substitute for proper structured studying. The key term there is "learning process" - you cannot learn all the things you need to know just by asking questions here. It isn't structured enough - it won't provide you with a way to progress where each step builds on what you learned before.

You can't carry out a job of this magnitude by asking whatever random questions happen to occur to you. What if you get something wrong because you have no idea your knowledge is wrong? What if you miss something because you simply have no idea it even exists, and just don't realise you don't know it?

You need an electrician.

 

[PrenticeBoyofDerry]

What sort of load can I put on radial circuits and how many sockets is my limit?

A 4mm2 radial circuit protected by a 32A device can take a load of 7360W
Rule of thumb, you can install as many sockets as practical.

 

[thewatcher87]

What sort of load can I put on radial circuits and how many sockets is my limit?

A 4mm2 radial circuit protected by a 32A device can take a load of 7360W
Rule of thumb, you can install as many sockets as practical.

It'll never have as much as that on it. Many thanks for all the replies. Just have to finish getting all these partition walls up.

The wife's uncle is an electrician and I will be getting him to check everything over before it's sealed up behind plasterboard anyway.

Enjoying all this DIY

 

[riveralt]

A 4mm2 radial circuit protected by a 32A device can take a load of 7360W
Rule of thumb, you can install as many sockets as practical.

Rule of thumb has been given the boot........ after complaints from fingers...... now the policitically correct term is .... historically

 

[PrenticeBoyofDerry]

By rule of thumb your historically correct!

 

[riveralt]

By rule of thumb your historically correct!

 

[ericmark]

I was involved in designing the wiring for a fleet of portacabins being re-furbished into twin unit housing. Location Falklands. We had many discussions as to best method.

* Ring circuits if broken can result in overload so seemed better to use radials as they fail safe.
* The cabins flex so considered flexible cable was less likely to cause problems in the future.
* The total supply likely was 32A so seemed pointless to have any MCB's with 32A or above rating. This also reinforced idea of radials.
* Lighting was also a problem where used outside of Stanley as power was not 24/7.

You need to do something similar. It is near impossible for any electrician not on site to take in every consideration. Likely something would be missed.

Living in a caravan some really odd wiring was done. The under sink water heater was linked to the electric heater so when there was a demand from the water heater the room heater switched off.

Not sure what changes have been made but at the time I was involved with portable living accommodation holiday units needed a 16A supply and permanent living units a 32A supply. Although often site owners did not make this available.

More resent with boats I have seen supplies as low as 3A as shore line supply.

On the other hand caravans used temporary while self building a house could have a 100A supply.

Insulation is a new problem and this may means cables need to be larger.

It would be normal today to supply everything through a RCD of some type. The rules for "MOBILE OR TRANSPORTABLE UNITS" and "ELECTRICAL INSTALLATIONS IN CARAVANS AND MOTOR CARAVANS" vary slightly from normal domestic and the first job is to determine what your unit comes under. One of the main problems is not being allowed a TN-C-S supply. It may also be required to have all pole switching on the RCD and really it is not so much what the rules say but what is safe.

I hate the name "Mobile Home" as it includes so many different types. One question that has to be asked "Is it a building"? This answer will change many things. The local authority building control is as the name says only interested in buildings. My son with his mobile home (A narrow boat) was more interested in "RCD" that's Recreational Craft Directive and again it was asked is a home recreational and does even that cover what is being done.

Any electrician with any sense will have insurance. And if he makes a mistake one hopes his insurance will ensure it is corrected. However most DIY work is not covered and any mistakes will be at the cost of the home owner. This will include electrical generated fire. Even as an electrician I would be calling my insurer to make sure I was covered. As these one off jobs can so easy go pear shaped.

 

[B67BU]

The radial will be easier as I can just run from one room to the next. If it was a ring it'll mean I'll have to double the cable on itself to the CU as the mobile is in two 30ftx10ft halves. What diameter of cable should I use?

What sort of load can I put on radial circuits and how many sockets is my limit?

Sorry for all the questions.

Have you seen this?