Removing redundant 2nd CU


Postby pete1801 » Tue May 08, 2012 7:08 pm

I just want to get some advice before getting an electrician in, as we don't know any so want to be able to know if we can trust what he's saying.

We've just moved into a new 3 bed house. One master and 2 small bedrooms.

The main CU feeds a 2nd CU upstairs in the 2nd bedroom.
The Setup is thus:

MAIN CU (Downstairs)
6A - Upstairs Lights (Master Bed)
6A - Downstairs Lights
32A - Downstairs Ring Main
32A - Ensuite Shower (via another 32A single breaker CU)
16A - Water Heater (Now Unused terminates at a fused switch in 2nd bedroom)
32A - Upstairs Ring Main (Master Bed) AND Second CU (in 2nd Bedroom)

SECOND CU (2nd Bedroom)
20A - Cable terminates under floor
6A - Upstairs Lights (2nd and 3rd Bedrooms)
16A - Upstairs Ring Main (2nd and 3rd Bedrooms)


We want to get rid of the second CU as it's really in the way and takes up much needed space in a small bedroom.
There are currently 2 feeds from the main CU to the 2nd bed - FEED 1 goes to the 2nd CU. FEED 2 used to feed the old water heater and now terminates at a fused switch in the 2nd bed.

Can I do one of the following? Is so which is best, and what concerns should I have...?:

Plan A
1) Remove FEED 1 entirely, from MAIN CU. Remove wiring, and 2nd CU.
2) Put FEED 2 into a new junction box under the floorboards in 2nd bed. Connect the "Ring Main" cable that currently comes from the 2nd CU. Thus converting the old 16A water heater circuit into a 16A ring main for the 2nd and 3rd bedrooms.
3) Find lighting cables in loft and connect 2nd and 3rd bedroom lights to existing master bedroom lighting circuit.

Plan B
1) Remove FEED 1 from 2nd CU, and discard CU. Put FEED 1 into a new junction box under floorboards in 2nd bed. Connect the "Ring Main" cable that currently comes from the 2nd CU. Thus feeding sockets in all 3 bedrooms from 32A "Upstairs Ring Main" circuit.
2) Put FEED 2 into a new junction box under floorboards in 2nd bed. Connect the "Lighting" cable that currently comes from the 2nd CU. Replace 16A breaker with 6A breaker. Thus converting the old 16A water heater circuit into a 6A lighting circuit for the 2nd and 3rd bedrooms.


Many thanks
pete1801
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Joined: Tue May 08, 2012 7:06 pm

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Postby ericmark » Wed May 09, 2012 4:34 pm

The regulations are written in a way to cover everything from caravan to factory so don't say things like you can't put junction boxes under floor boards but in order to do so one would need a hatch which has access and putting carpet over the hatch would also mean a removable section of carpet to give access.

There are special maintenance free junction boxes and it does come down to interpretation as to what is and is not allowed and as electricians we often have heated arguments as to what is and is not allowed.

The point is does not really matter what is allowed in the end I am sure you want something safe and selecting an electrician who will do as you want may not be the best option.

DIY people tend to call any socket system a ring. However there are also radial circuits. So to answer purely on your report may be very wrong as there may be many things wrongly reported.

It may be possible using fused connection units (FCU) to do away with the consumer unit. But one questions why it was fitted to start with? There are also flush fitting consumer units.

One major problem is in 2008 the rules were changed and although one can continue with old system once one starts to change things then likely one will need to comply with new system. So likely one will need to replace the existing consumer unit so that RCD protection can be added. Before doing this a inspection and test would be normal to see what else will need upgrading. Two way stairs lighting often causes a problem so it is likely some wiring will need altering.

So from experience I would expect you will need new consumer unit and the three circuits fed by the second second will be extended to be fed by the new unit.
ericmark
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Joined: Fri Oct 02, 2009 8:49 pm
Location: Mold, North Wales.


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