Sub Board Query

[wreck-it-steve]

Hi,

I need to get a new two way board fitted next to my existing board to supply two double sockets and one light... The electrician doing the work has told me what I need to buy:

1x 2 way board
1x B6 Breaker
1x B20 Breaker
1x Set of 16mm tails

My question is this: the board will be fed direct from the henley block but do you need 16mm tails for such a small load? can 6mm or 10mm cable feed the board direct from the henley block?

Thanks

 

[flameport]

Why do 2 sockets and one light require an entire new consumer unit?
Why isn't the electrician supplying the required parts? You buying them won't save any money and it means you could easily buy the wrong items.

The answer to the question is - cable smaller than 16mm may be permissible, this depends on certain other factors.

 

[wreck-it-steve]

Why do 2 sockets and one light require an entire new consumer unit?
Why isn't the electrician supplying the required parts? You buying them won't save any money and it means you could easily buy the wrong items.

The answer to the question is - cable smaller than 16mm may be permissible, this depends on certain other factors.

the new board is full and i require the new circuits for a computer room... i have specified it like this. i am getting the parts as i have family in the wholesale trade so it is cheaper.

what are these factors?

 

[ericmark]

433.2.2 The device protecting a conductor against overload may be installed along the run of that conductor if the part of the run between the point where a change occurs (in cross-sectional area, method of installation, type of cable or conductor. or in environmental conditions) and the position of the protective device has neither branch circuits nor outlets for connection of current-using equipment and fulfils at least one of the following conditions:
(i) It is protected against fault current in accordance with the requirements stated in Section 434
(ii) Its length does not exceed 3 m, it is installed in such a manner as to reduce the risk of fault to a minimum, and it is installed in such a manner as to reduce to a minimum the risk of fire or danger to persons (see also
Regulation 434.2.1).

This is the regulation as far as using under size cables, The suppliers fuse protects 16mm cable but when reduced in size it's the MCB's in your board that protect the cable. In real terms the problem is you need double insulated tails and your unlikely to be able to buy short lengths in a size not commonly used. So to buy thinner cable will likely mean you need to buy whole role rather than short lenght so will be more expensive.

The other consideration is there is a minimum size at which the large terminals of a henley block will grip the cables.

Also if you look at 6181B LSZH Double Insulated Cable 600/1000V BS6724 for example smallest made by Batt Cables is 25mm. 6181XY Double Insulated Cable 600/1000V BS7889 and 6181Y Double Insulated Cable 300/500V are made in smaller sizes but as to whole sale outlets stocking the cable that's another question. Since meters and consumer units tend to be in entrance areas using 6181B LSZH Double Insulated Cable 600/1000V BS6724 which is low smoke would seem to be the right selection.

 

[ricicle]

the new board is full and i require the new circuits for a computer room... i have specified it like this. i am getting the parts as i have family in the wholesale trade so it is cheaper.

Stop lying and tell us the truth - you are looking to do this yourself aren't you ?

If not then you should be asking your electrician not a DIY forum !

 

[ban-all-sheds]

Stop lying and tell us the truth - you are looking to do this yourself aren't you ?

I think you might be right:

I need to replace a faulty RCBO in my consumer unit and can only seem to get hold of type C. Is this OK to use in a domestic property? Maybe it will stop the RCBO tripping when a bulb blows?

I have a Merlin Gerin Isobar 4 board and my local wholesaler says they dont do type B for them.

Can the wires from an RCBO be cut to length for the consumer unit? There is too much lenght on the earth and neutral, also is there any reason why the neutral is coiled?

I have a 10 year old contactum consumer unit and im trying to source an MCB for it. I have looked all over and the only one i can find that resembles it is this:

http://www.vulcanelectrical.co.uk/contactum-7106b-mcb.html

anybody know if it would fit?

 

[Taylortwocities]

Hi,

I need to get a new two way board fitted next to my existing board to supply two double sockets and one light... The electrician doing the work has told me what I need to buy:

1x 2 way board
1x B6 Breaker
1x B20 Breaker
1x Set of 16mm tails

Stevo. Your post does not mention the magic letters "RCD".
Did your electrician happen to mention this?