New consumer unit MCB's - what do I need as a basic start?

[flameport]

If you qualified eletricians where offered a job lot of consumer units would you buy them? Im not talking about someone in a pub offering you them but from a wholesaler or something - I think you would

The only instance where a whole load of identical consumer units would be required is for a new build block of flats or housing estate - and in those situations, they would generally be supplied preconfigured specifically for the job by the manufacturer.

Otherwise, each property is different and will therefore require a different unit.

 

[sparkiemike]

and wouldnt mind confirming which ampage mcb's I need based on my description below:

Shower - 50 AMP
Cooker - 32 AMP
Kitchen Sockets, cooker hood, hob ignition - 32 AMP
Bedroom sockets, Garage sockets - 32 AMP
Lounge, Hall Sockets - 32 AMP
Lights - 6 AMP
Smoke Alarm - 6 AMP

Based on that description, you need what is listed there.

However -
is the supply to the bungalow suitable for adding a 50A shower circuit?
is it even suitable for what is already installed?
what type of earthing system?
what type of wiring system has been used?
how many RCDs were you intending on having? If more than one, which circuits on each one? or perhaps RCBOs? or some combination of both?
are those sockets on rings or radials?
how many outlets on each circuit? or the total expected load for each?
what about all the other things you don't know about?

Perhaps the OP is expecting the electrician to design it and then write out a shopping list

 

[shabbaranks]

So again, going slightly off topic and I realise it would depend on the electrician. Would you be prepared to wire to a consumer unit wires that have been run by the customer? Or would you want to do the whole lot in order to give job assurance?

 

[Electrifying]

So again, going slightly off topic and I realise it would depend on the electrician. Would you be prepared to wire to a consumer unit wires that have been run by the customer? Or would you want to do the whole lot in order to give job assurance?

Again, it's not going to save you anything - because the electrician will have to allow (in his price), for inspection of everything you have done prior to him getting there.
Then there's the 'putting right' anything that he's not happy with.

Then there's the 'fault' phone call.

"Hi, Mr Sparky, my RCD keeps tripping - could it be something you've done?"

"Don't know, mate, might be the dodgy cable you bought and fitted"

I, personally, price for design, installation, Inspection, Testing & Certification - job lot.....end of.......and that's what's guaranteed.

Customer can put their tuppence worth in towards design, but that's it.


So, get a few electricians in to price the job and stop p*****g about.

 

[sparkiemike]

If you are in England or Wales are you aware that this work is notifiable under part P of the building regs? You need to notify LABC (local authority building control) or get a registered electrician in to do the work. If it is the former then you need to notify LABC before you start any of the electrical work and they will advise you on any conditions they may impose on you. If it is going to be the latter then your electrician will be best placed to advise you, and he will probably insist on doing all the work - I would.

As prevously stated, contrary to what you may hear from the likes of Sarah Beeny on the telly, you can't just get somebody to "sign it off" at the end or just do the final terminations. I would direct you to the Part P approved document and see paragraphs 1.28 and 1.29. (google it for a free download). I certainly would not want to take on responsibility for your work.

 

[ban-all-sheds]

Whys that then? I thought that I can run the cable and get an electrician to fit the consumer unit?

No - you can't.

The electrician has to certify that he did all of the work - the design (which includes sizing the circuits, selecting the cable routes, deciding on methods of installation), the installation itself, and the testing.

He has to certify that he did it, that he exercised reasonable skill and care in doing it, and that to the best of his knowledge and belief it complies with the Wiring Regulations.

He has to certify that it complies with the Building Regulations.

He cannot and will not do those things if you present him with cables you've installed, a CU you've bought, and a request to just connect it up.

It's not just "job assurance", it's regulations and laws.

Also the prices online for the consumer unit complete with MCB's are extremely competative to those available to a couple of electricians I have spoken to so I thought it made sense to buy it?

If they are cheaper then it's because he is adding a markup to them.

So, let's say that the total price for the rewire, with the electrician supplying the parts, is £4,000.

And let's say that that is made up of:

Materials £750 (cost to him)
Markup £500
Labour £2750

So - you see his quote:

Materials £1250
Labour £2750

And (remembering that you won't be able to buy as cheaply as him) you think "Hang on - I can buy the materials myself for £900 - that's going to save me nearly 10%".

Now - one assumes that the electrician has struck the right balance with his £4K price and his gross takings of £3250 between being competitive and being able to put food on his table.

So - faced with getting £500 less, will he:

a) Say "OK", and not be able to pay for his shopping for a few weeks?

or

b) Just add it into his labour costs, at which point your rewire price becomes £4,150?

 

[Electrifying]

Sparkiemike is spot on.

Additionally, what you don't seem to take into account, is that the electrician has to sign this (or something similar):

FOR DESIGN, CONSTRUCTION, INSPECTION & TESTING
I being the person responsible for the Design, Construction, Inspection & Testing of the electrical installation (as indicated by my signature below), particulars of which are described above, having exercised reasonable skill and care when carrying out the Design, Construction, Inspection & Testing, hereby CERTIFY that the said work for which I have been responsible is to the best of my knowledge and belief in accordance with BS 7671:2008 amended to .......... (date) except for the departures, if any, detailed as follows

He then has to notify the job via his 'scheme', certifying that the installation complies with the 'Building Regulations'.

So, most electricians will not be happy with you wanting to do half the job to try and save a few pound.

 

[Electrifying]

And what BAS said!

 

[plugwash]

If you qualified eletricians where offered a job lot of consumer units would you buy them? Im not talking about someone in a pub offering you them but from a wholesaler or something - I think you would

The only instance where a whole load of identical consumer units would be required is for a new build block of flats or housing estate - and in those situations, they would generally be supplied preconfigured specifically for the job by the manufacturer.

Otherwise, each property is different and will therefore require a different unit.

Well given the likes of screfix sell fully loaded consumer units there must be a market for them.

The thing is while there is some variation it's not that unreasonable to make a unit that will cover most domestic properties while leaving some expansion room. Most houses have a pretty similar complement of circuits (3 rings, 2 lighting and a handfull of others that vary from house to house). Some installs may require you to swap out the odd breaker (e.g. to change the rating of the cooker or shower breaker) but that is probablly still less effort than building the unit from scratch and personally i'd rather have unused breakers than have blanks*.

*it can get difficult to buy breakers a decade or so down the line and the cover mount blanks that seem to be common nowadays look WAY too easy for kids to remove for my liking.

 

[Taylortwocities]

Lets have a look further at the

Shower - 50 AMP

What is the rating of the shower?
What makes you think you need 50amp CPD?
What is the CSA of the cable, its length and what is it routed through?


and

Smoke Alarm - 6 AMP

It is not recommended to have smoke alarms on a separate breaker. Its better to run them from a regularly used lighting circuit. Then you know if the breaker has tripped.

Only one lighting circuit?

 

[flyingsparks]

Smoke Alarm - 6 AMP

It is not recommended to have smoke alarms on a separate breaker. Its better to run them from a regularly used lighting circuit. Then you know if the breaker has tripped.

I use to agree with you on that one, but then I heard (cant remember where, and dont know any regs to back this up..) that smoke alarms should now be on their own dedicated circuit?

 

[sparkiemike]

I use to agree with you on that one, but then I heard (cant remember where, and dont know any regs to back this up..) that smoke alarms should now be on their own dedicated circuit?

It depends on the grade of alarm system as defined in BS5839-6
For Grade 'D' which is what you are likely to have in a domestic dwelling (Grade D: A system of one or more mains-powered smoke alarms, each with an integral standby supply) a regularly used lighting circuit is recommended for Grade D systems.

EDIT:An independent circuit is also allowed

Grade ‘A’, ‘B’ and 'C' fire detection and alarm systems are integrated systems generally incorporating a control and indication panel or panels, and are the only systems that require separate circuits.

This is also the guidance from the NICEIC

 

[flyingsparks]

Thanks for clearing that up sparkiemike!!