New extension - how do I know if fuse box big enough?

[mrsdecisionmaker]

Hi, I hope you can help. I need to speak to builders about our extension and want to be able to ask the right questions. We had a new consumer unit installed 13 years ago ( label says not to exceed 100amps). The house is 1950s not been rewired and we will extend it with 2 new bedrooms, 2 new rooms downstairs.

How do I know if there is enough room in fuse box to add on new circuits for the extension? All of them are labelled up.

Is it worth rewiring existing house (3 beds) and what is scale of cost ?

 

[PrenticeBoyofDerry]

You wont get a Consumer Units rated above 100amps.
If your wiring is 60 years old, I'd suggest you have new Consumer unit installed and the new cables too.
The cost will vary from region to region and the size of your house.
The work must also be notified to your local building controls, this can be done by you or by the electrician.
An electrician who is registered with a scheme provider, will be able to self cert the installation.

 

[SparkyNinja]

It is probably worth considering having a rewire.
Get an electrician or two to come in and quote you for both.
If the builder has an electrician, make sure he's registered to do the work.

 

[mrsdecisionmaker]

Consumer unit is 13 years old. If you can't get bigger than 100amps is it worth changing this ? Will they just add new lighting circuits onto existing ones

 

[PrenticeBoyofDerry]

Yes it may need changing! because the regulations changed in 2008 and your board may not be to the new standards.
Does it have RCD protection or can you install RCBOs on the board?
As far as new circuit that will depemd on your current load.

 

[mrsdecisionmaker]

Consumer unit is a 'contactum' and says RCCB on one label, also on paperwork it says RCD. Looked at contactum website - but it is being updated so not a lot of info there. Who are the main suppliers of these? What makes would you recommend ?

 

[Chri5]

It would be helpful to take a photo of the existing CU and surrounding area.

Normally for simple room extensions the contractor would extend the 1st floor ring for the bedrooms and do the same for the ground floor rooms.

There is a but.... and that requires an assessment of the overall state of the existing wiring system, the standard of the previous work has been done to and the load / use of the circuits.

Take bedrooms, low use level, short period of use each day- electrically it's unlikely that there would be any load issues.

Down stairs could be completely different and it sort of depends what the rooms will be used for and what electrical items will be used.
Say you intend to create a utility room or provide electrical heating- both will require design and load considerations.

If new circuits are provided they will have to be completed to BS7671: 2008 which brings in to play RCD's or RCBO's and main bonding of water and gas pipes.

 

[ban-all-sheds]

The house is 1950s not been rewired

So it could still have VIR cables.

Get a periodic inspection done.

 

[Steve]

Consumer unit is a 'contactum'

It definitely needs changing then Contactum = cheap stuff that electricians fit so they can charge less and get the job.

That aside, yes, you should have a rewire. If the extension is substantial - and will involve extra electric heating / heavy loads like an electric shower or whatever, then you may need a new CU. And they will have to work to 17th edition for existing circuits if they extend them, which will mean replacing the CU too in most cases.

 

[RF Lighting]

Didn't contactum go bust about a year ago?

 

[Adam_151]

Didn't contactum go bust about a year ago?

This did... well nearly, but then got bought out and are back up and running now

 

[securespark]

Check the CU's before you buy them, some are a bit charred.