Self Build Advice Please - consumer units, sockets & switches...

[janner43]

Hi all,

We are doing a self build 2 bed bungalow in Devon which is going to be very highly insulated with u-values of..
Floor 0.15
Walls 0.14
Ceiling 0.11

With an air tightness factor of 0.8
MVHR with 89% efficiency

* Our other design spec includes no central heating system (not required with the previous specs), we'll just add a panel heater to act as a top up for the stored heat within the home when required. The MVHR should do the rest.

* An "experiment" with no central hot water - just local instantaneous water heaters (3 @ 12kw) where required. Half the plumbing, no dead leg of water, no waste hot water stored. We are not having a bath, so an instantaneous electric shower (9.5kw)

* We are having a 3.7kw solar array. The whole concept is based on the PassivHaus model with a couple of tweaks.

I don't really want to debate the design concepts - feel free to comment if you like, though .
The whole idea has been predicated on thinking differently about the designs when it comes to the heating and water heating together with an avoidance of the connection costs, plumbing, boiler purchase, boiler servicing costs associated with a gas connection (which is available).

We have a great, fully qualified sparky on the project who grew up with our son & is a good guy. I know he'll give us good advice, but I would appreciate several points of view on this please. He is kindly not supplying materials & is letting me source those to save some money. He is also arranging for a pal with the MCS ticket to commission the solar array at mates rates.

That's the background, now to the questions...

1) Consumer Unit...
I wondered if it would be a good idea to have two consumer units...
One for the heavy items - three 12kw water heaters and one 9.5kw shower
One for everything else

Or just get one large unit?

Would there be an issue with the solar array connectivity if we had two consumer units?

I like the idea of splitting as many of the circuits as possible, so what sort of config would you design if this was your build?

2) What brands are the best value for money - I'm familiar (Dad was an electrician for decades, started his trade in the 1950s) with MK, Wylex - but are they as good now as they were or are other names just as good?

3) Any recommendation on which make of sockets & switches to get?

4) Any recommendations as to the cheapest place to buy the gear from please? I already have a Trade Account at Travis Perkins (and Trade Point - don't laugh, it might be handy... )

I hope I have given you enough information & thanks in advance for taking the time to read this and for any answers / opinions / recommends you might be willing to give.

Cheers all.

 

[7029 dave]

IMO these questions should be discussed with your Electrician on site, are you doubting his integrity, If I were him would not be best pleased in the slightest, sorry but if you are going to have an hissy fit over some Q's then IMO there is no other spark is there.!! It's an selfie.

 

[davesparks]

It isn't what we think about it that matters though Dave, is it. Apparently that is a serious proposal that is being considered - I know it seems hard to believe, but I only know what I have read...

And I know what I've read, in one of the DNO's technical papers detailing how chunks of the distribution system are still working on DC distribution from around 100 years ago.

 

[jackhammerJIM]

It isn't what we think about it that matters though Dave, is it. Apparently that is a serious proposal that is being considered - I know it seems hard to believe, but I only know what I have read...

The muppets that run this country are not going to scrap gas . For one the energy companies themselves would not allow this as a loss of revenue (they are powerful) .

We are on the limit for power as is . Not enough power stations and fear of brown outs in the near future if they don't get arses in gear !

They look like genuine articles but this is the first i have heard of the idea . Not going to happen , If gas is available you would be foolish not to utilise it .

 

[Octopus]

the property should be built with gas, electricity and a wood burner - then you've got the bases covered!

 

[Lagentium]

I'd go ground source heat pump and forget those instant water heaters rated at 12kw, they are a daft option IMHO, but that is just my opinion.

 

[janner43]

OK, thanks to everyone for your advice.

The thread can be closed now as far as I'm concerned.

 

[gaz101]

No diversity allowed on water heaters
what's the cost of a 50kva+ supply?

 

[Midwest]

The muppets that run this country are not going to scrap gas . For one the energy companies themselves would not allow this as a loss of revenue (they are powerful) .

We are on the limit for power as is . Not enough power stations and fear of brown outs in the near future if they don't get arses in gear !

They look like genuine articles but this is the first i have heard of the idea . Not going to happen , If gas is available you would be foolish not to utilise it .

There was a debate here, on this issue a short while ago. Can't be bothered to locate it, but suffice to say the UN Climate Change Conference 2015, agreed on a reduction of 2' of global warming, and less reliance on fossil fuels, by 2030. Whether it will happen or not, as the agreement doesn't appear to be biding. In the UK, apart from fuel for vehicles, a lot of our carbon emissions come from, gas heating and gas cooking. Whilst some effort is being made on carbon emissions from vehicles, little is being done with our gas consumption. Hence the headlines about the demise of domestic gas boilers and hobs.

 

[joehat]

You should not plan an installation which relies on this though, the fuse will weaken with time as it is subjected to such overloads and the terminals etc of the cutout won't necessarily be rated for the duty.

Agree, gonna have a look in abit as I'm nosy ,but do you remember where you found this info Reg Ect.

 

[joehat]

You should not plan an installation which relies on this though, the fuse will weaken with time as it is subjected to such overloads and the terminals etc of the cutout won't necessarily be rated for the duty.

Specially with the cheap and cheerful options.

 

[Leesparkykent]

Agree, gonna have a look in abit as I'm nosy ,but do you remember where you found this info Reg Ect.

Its common sense really but 433 covers protection against overload current. 433.1, 433.1.1 and so on.

 

[davesparks]

Agree, gonna have a look in abit as I'm nosy ,but do you remember where you found this info Reg Ect.

Common sense and experience is where I got it from.
Common sense: don't design an installation which relies on a fuse running at more than it's rated current.
Experience: fuses which run at their rating/just over there rating get weak and blow for no apparent reasons.
Also from experience a 100A cutout being regularly loaded to 120A will get very very hot and smell rather nasty (overload revealed from a load study carried out after the cutout was replaced)

 

[plugsandsparks]

100A fuse ? I would get that in writing before making such a design assumption. 63A more likely me thinks

 

[sean_ork]

OK, thanks to everyone for your advice.

The thread can be closed now as far as I'm concerned.

Don't be disheartened, many trades in this Country don't like change, most builders still think block/brick build is the only way - ask them about air tightness testing and you'll get the same belligerent responses as you've seen here.

We've done very similar to what you are aiming at, but before PH became trendy - luckily we have an almost endless supply of energy blowing past so our energy source was easy to pick. Your calcs probably show you won't need any significant energy input for space heating, as did ours - but we specified all flooring to be highly insulated 8'' conc with both electric loose laid heating, and wet UFH - and a fairly large TS - with plenty of coils, stat probes and three immersions - lots of thermal mass.

Your instantaneous heater proposal is sound - heat at the point of use, and only heat what you need is a concept clearly lost so far in this thread.

But do ensure you pander to those who might live in the house after you by ensuring gas is at least piped to the likely areas of use, you don't need to have a supply, just a feed from your utility box.

We spent time in Norway and Sweden before signing off, they know how to build properly over there - hopefully trades in this Country might catch them up eventually.

You'll likely be aware already, the Green Building Forum will be much more receptive of your "wild" ideas - also talk to Viking House, they have some innovative MHVR solutions - also their general building and detailing drawings are a goldmine of ideas.

Good luck.

 

[joehat]

Its common sense really but 433 covers protection against overload current. 433.1, 433.1.1 and so on.

I would have looked in that section yes but would never design above 100a do didn't know it has that in the regs book as its not ours to touch,, soso!!