2 consumer units

[ulluullu]

I am in the middle of a new build house construction (bungalow) where the runs from the main consumer unit (if there is only 1)
will be in some cases nearly 60 meters of cable. So i was thinking, that it might be smarter to put a second consumer unit at
the other end of the house and run a *big* cable over to it from the supply, rather than running so many expensive long cables
for individual circuits. What i've read about is about installing a garage... but i'm thinking something a little heavier duty,
1/2 a house.

If anyone has any advise and thoughts about this, please.

To the same structure, i am installing the conductors for a lightning protection system, These are equipotentially bonded
to the steel structure, the rebar and about 10 tons of structural steel fixed to the bedrock. Would you connect the house
ground to the lightning protection ground? Or would you try to put a separate ground in for the house that would not spike
when the structure is being zapped by lightning? The building is on an exposed location in the inner hebridies, where it is
the highest point for miles - hence the LPS. In this regard, i am preparing to run a portion of the house electrics
using an inverter and renewable energy batteries as a lighting isolated electrical system; how would you establish the earth
for this subsystem (another separate earthing point?). How would you protect from lightning when you expect the house
to be struck once every 2 years?

 

[ulluullu]

I have not buggered off, just away in the physical world. I'll take your advise and have a chat with furse.
The structure: Is surrounded by peat bog, and when complete will have a peat bog roof. This peat bog
roof will be constantly wet, weight about 100 tons on a waterproof membrane of roofkrete, which is
a hybrid of cement set on galvanised steel mesh like a swimming pool. This however is a floating ground,
and the roof peat bog is on a layer of insulation and wood that makes it literally a floating ground.

One approach to an LPS would be to simply put the rods on copper feet in to the wet peat roof,
and to tie the floating earth. What i was planning was to use wall-mounted conductors to take
a lightning earth down the foundation for fear that a bolt hitting the peat-bonnet would burn through
the waterproof membrane destroying its waterproof nature to the steel grounded structure beneath.
So to preempt this, the current LPS design ties the air rods to the founds.

Due to the experimental nature of living roofs and the fire-concerns of grass fires and insurance, LPS
design is more self-insurance in this regard.

 

[Spudnik]

I would say that the installation you are about to embark on, will need some serious design behind it.

Of course, we are all here to help should you need it.

Good luck.

 

[ulluullu]

Apologies for not answering - the runs are in the ceiling, some hung plasterboard. For simplicity sake, the floor screed is reserved for underfloor heating pipes.

Visible in the photo, the central steel cage (the camera views down on it because i'm holding it up high over my head on the highest near hill top.)
is asking for a lightning strike being the highest point for 360 degrees. Structure is durisol forms with poured rebar-concrete as the structural walls.

 

[trev]

Looks like a nice spot mate

 

[Engineer54]

The problem i see with you LP system using the steel frame via the foundations is side strikes into the home which could pass thru any plaster board boarding out used. Not a risk i would like to take anyway.

Trouble with hybrid roof systems, there is no sure or proven ways of how they perform in all or certain circumstances. So it's far better you getting professional advice on your LP system, though there is a good chance they won't be too clued up on your hybrid roof either!!

So what are the advantages your hoping for, of using this peat based roof??

 

[Engineer54]

You haven't confirmed or otherwise, that your electrical earthing system is or will be TT system.

If it is, i would personally take the LP down conductors down the outside walls and at least a couple of metres or so past your house foundation. Thus keeping the structural steelwork isolated from the LP system. Air conductors can run along the top of the parapet that runs around the roof. Where your solar panels are mounted you will need to have air spikes that are at least a metre above the height of the panels. You will also need surge protection incorporated into your solar system too... but that's a whole other matter that you can also discuss with furse...


By the way, did you Ufer your house foundation, ie.... connect the re-bar to an earthing cable, or bring out a section of re-bar beyond the concrete as a connection point for earthing??

 

[ulluullu]

It was one of the planning giveaways to achieve such a modern structure, that the bog at the founds be restored on the roof as a "green" architecture,
but also as the living roof will absorb all the UV rays that normally break down a flat roof structure, and the peat is an excellent insulator, so half the roof
insulation is supplied from the local biomass. The peat bog is exceptionally beautiful when it is in bloom, the whole roof will be purple in the month of september.
The insulation value of the roof is targeted to U .1 including the peat component, and with the windows at U .6, and with the buried walls, the house is using
the european roller shutters on daylight switches open like eyelids to let in passive thermal heat, possibly. Will it meet passivhaus standards? Time will tell,
so much depends on the finish quality.

Another reason was to add substantial mass to the structure that the extreme winds of the location ( not far away just days ago the wind speed measured
at 165mph) not make it shake or noise even well over 200mph. Windows all coming from germany.. non traditional is indeed difficult, but engineering exists
for such things or oil platforms in the north sea would be sinking.

 

[ulluullu]

No the foundation is not uferd, however, there are 14 universal columns welded to 600x600 feet (all hot dipped) bolted to the bedrock and set in
solid concrete founds. THe rebar is been tied together throughout the structure with stainless steel ties, though for structural reasons, not for
grounding, but i'm comfortable that with the kind of voltage in a lightning strike, that these interfaces would prove conductive. Conditions are
wet at 2.5 meters of rain per year at the location, so soil conductivity is excellent.

Yes its a TT system. I like your LPS solution better, i would rather use the house structure as the non-spiking earth; i'll look in to the
"ring" LPS solution putting the earth in a circle like you say around the founds in the wet ground of the peat bog, and take the LPS conductors down
as spokes to that wheel.