Garage - Ring Main or Radial?

[lesh00]

Hi, new to this forum and have a question to ask.

My attached garage currently has a radial circuit with the lights also coming off of the same radial circuit via an FCU. All using a 2.5mm twin and earth.

There are currently 2 double plug point sockets in the garage and I'm looking to add approximately 5 more double plug points and whislt doing so, could quite easily turn this circuit into a Ring Main.

My questions are:

1. Is there a legal requirement to inform the local council of this?
2. What are the pros and cons of doing this?

(The cable length in total is no more than approximately 20 meters).

Thanks for your help.

 

[ban-all-sheds]

I'm looking to add approximately 5 more double plug points and whislt doing so, could quite easily turn this circuit into a Ring Main.

Are you sure?

You'd have to replace the MCB in the CU with a higher rated one, and all the testing for continuity, fault loop impedance etc that entails.

http://www.tlc-direct.co.uk/Book/8.1.1.htm

1. Is there a legal requirement to inform the local council of this?

Well...

I don't think that anybody would argue that it wasn't the intention that it should be notifiable, given the complexities of doing it and the serious risks if done incorrectly, but the way that Schedule 4 is actually worded could be said to make replacing an MCB non-notifiable if you did the work in an artificially convoluted way.

The concern with you DIYing it is not the degree to which you'd be evading notification, it's all the testing which should be done.

2. What are the pros and cons of doing this?

Pros: The ability to support a greater total load than with a radial. What's the existing MCB, and how much do you need in the garage?

Cons: Harder to extend in the future, needs testing, cost of another MCB.

 

[ericmark]

I would agree with BAS.
To form a ring rather than a radial gives three advantages.
1) Current can be increased on the circuit.
2) The earth loop impedance will drop.
3) The volt drop will be reduced.
So question is why do you want a ring?
a) Is there a problem with the MCB tripping.
b) Is the loop impedance going to be too high.
If the answer to a) and b) is no then no point in forming a ring.
Typically a radial will have a 16 or 20 amp MCB and a ring a 32 amp MCB although not only cable size but also route has to be considered. The earth loop impedance allowed changes with size and type of MCB used.
Do you know the earth loop impedance?
Do you even know what it is?
How would you measure it?
The problem with most DIY work is lack of testing. The test set I use cost around £750 and most DIY guys just havn't got the money to buy or rent one that's why they turned to DIY. So to put it in plan languages for electrics for DIY read "Chancer".

 

[B67BU]

Hi, new to this forum and have a question to ask.
There are currently 2 double plug point sockets in the garage and I'm looking to add approximately 5 more double plug points and whislt doing so, could quite easily turn this circuit into a Ring Main.
My questions are:
1. Is there a legal requirement to inform the local council of this?
2. What are the pros and cons of doing this?

Thanks for your help.

Take a look at this