Help! Domestic rewire- one or two consumer unit?

[Alottasparks]

I have this 4 bedroom 5 storey house which is being completely re-wired atthe moment, originally the electrician said he'll put in a single large split 15 fuse consumer unit, now he is saying 2 separate 10fuse consumer units... I can't help but feel maybe it's because 2 smaller ones may be cheaper than one single large one perhaps? No idea why he is wanting to change and he just says it's better. Please can someone shed light on this, what is the better option?

 

[Phil]

id nee a bit more info really on the location of the consumer units. sometimes may be limited to the wall size and have to place one below the other etc. i suppose two units may also help in less inconvenience in the event of the rcd tripping, depending of course on how the curcuits are designed.

 

[Phil]

also i would not have said it was due to pricing tbh, probably more expensive for 2 separates than one 15 way

 

[terminator]

He's probably going to save you a bit of money by having one on ground floor and sub main to one on upper floors - cuts down on a lot of long cable runs!

 

[Alottasparks]

I told him to fix it in one designated place so no savings on the cables! There is enough space for a large consumer unit as well as if he wanted one below the other (it's in the cellar of the house). Just don't really trust the guy as he promised a niceic qualified sparc to do the job and now I'm seeing 2 decorators doing all the pulling of wires and chasing of Walls for the first fix without supervision... He tells me it'll be someone qualified to do the connection but am worried it's all going to go pear shaped. Oh and by the way it wasn't a cheap quote either...

 

[terminator]

As Phil7677 says, we need to see design really - its hard to say without more info!

 

[Paul.M]

A supervisor needs to be on site to oversee the cable run. Gets this guys nic reg number and call them.

 

[Ponty Massive]

If your concerned with the guy tell him. Your the paying customer (and as you say he's not cheap). Have a double check of his niceic registration. Got nothing against the decorators chasing the walls (best place for them) but a bit naughty if they are pulling cables and first fix !!!

 

[Phil]

have you had a look on the nic site to ensure he is registered? i would tell them to stop working if you are concerned until the electrician comes back on site. like the previous posts have said you could give the nic a bell.

 

[NMc]

Need to get more info on this one - he may be thinking about the possibe furture additions. I believe a 15way is about the biggest and if he is installing 15 circuits then this may be the reason why!!!!!!!!!!

 

[Phil]

on the boards i would prefer it to be on two separate boards if i were you tbh. in the event of the rcd tripping if he has designed it well then you should have less inconvenience regarding loss of power to parts of the house as it will be on 4 separate rcds

 

[NMc]

Phil has a very goood point with which I agree. This is a big installation and a long way down form the top (5th storey) to reset a trip in the dark

 

[madrid]

If the consumer unit has to go in one place there a number of manufacturers who make larger consumer units.Legrand,wylex(although may be special order)MK sell a stacking kit so you can add an enclosure to their consumer units.contactum do a 22 way board.although as said previously might be a good idea to run a sub main to 2nd or 3rd floor to cut down on cable and ensure loop impedance readings are ok.

 

[ash_s3]

Could you not use a Merlin 36 way board with a single phase kit? Would have plenty of room inside and plenty of scope for future additions.

 

[Engineer54]

As you all probably know, i'm not in favour of multiple separate CUs in standard sized house's. However, this is Not your standard sized house by any stretch of the imagination, and in this case 2 CUs is perfectly justifiable.

It will be far more convienient for the owner, and reduce overall cable requirements, among many other advantages and benefits....

The OP needs to insist that the responsible electrician overseeing these none electrical labourers makes frequent visits to site, to ensure his installation is compliant to BS7671. Ideally he should be on site full time during the 1st fix wiring stages....

 

[randym68]

I agree with engineer54 , i have done an installation of this size and had to split lighting into 4 lighting circuits, 4 socket circuits, 3 ensuite showers , ya 15 way will not allow 15 MCB's will generally allow 7 + 6 with RCB kit to create two RCB/RCCB buzz bars...which is a requirement as said above to allow user to find their way to CU if one RCD/RCCB goes.

two 10 way CIU's can sometimes be cheaper, i get 12 ways (6+6) inc choice of MCB's for £50 , but a 15 way from same supplier is £110 inc second RCD then extra for and individual MCB's.

but you are right to question first fix, current 17th has a large emphasis on installation method, and without installing self you cannot be shure they are not burried in insulation. (upto 50% reduction in current carrying cappacity) just waiting for a fire.

second , my experience of decorators is they over do everything pull on cables, and thus reduce the CSA (cross sectional area) of a conductor. again reduce current carrying capacity... and will not necessarily show up on continuity test (second fix testing the electrician will do ) ..as long as the ohms reading is small enough it passes. but you get a hot spot ...and this hot spot 9 times out of 10 is where its a tight fit in a joist in bundle... again fire waiting to happen. and sods law being applied, they will shove some insulation in there to make it worse. just and example of how important a suitably qualified person should supervise or being doing first fix.

probably too late to help but others may appreciate