If they are being classed as a separate installation, then surely you would base the bonding conductor csa on the supply conductors for the individual installation?
Generally the combis are 30+ kW in order to give decent hw flow rate. Electric boilers will most likely require a return to immersion tanks to even out electrical demand for hot water heating. A reservoir of high energy molecules...
Quite common to find system boilers in 12 to 18kW band.
6mm t+e run through 25mm conduit on the external section would be simplest. Don't really like t and e in conduit, but no point adding unnecessary joints for sake of it, and twin will be easier to route on the internal sections.
Probably more a buerocratic decision based on harmonised standards. That said...aren't those spurs 'active' not 'passive' rcds or something like that? So maybe there is a technical reason? Do they fall under the same standard as rcd plugs for use with flymos etc?
Trouble is that now there are battery angle grinders, the bastards see the heavy duty locks on the van, figure there must be something expensive inside, and get in by angle grinding the roof open!
The standard that they are manufactured to is not listed as a means of providing additional protection. Can't recall if it used to list it, or if it just said 30ma, but now it just says a 30ma device to 61008 or 61009 i think
I think this is why earth is stripey! Even if the colours are on the limits of what can be distinguished, the stripes instantly make the earth recognisable.
It's perfectly possible that his business offers all those services via specialist sub contractors or employees... Isn't that what most building companies do? One point of contact for customer, builder runs the job and deals with trades.
Or he's just a handyman that can do the basics of each...
I'd wager the rings were put on b20's due to reference method 101, that basically means you'd need to do an rfc in 4mm if you used a 32a breaker. I'd also bet that they'll never trip on overload unless the boiler breaks and someone buys 10 fan heaters!
Personally I'd prefer to fit a Hager high...
It's possible the 3 phase supply was required for max demand, rather than needing 3 phases for 3 phase kit. If it's a big house with all electric space heating that might have been the reason. It's unusual to find a 3 phase head in domestic unless it needs to be there for extra kW. Worth...
Certainly sounds unorthodox. Not necessarily wrong though, but I do wonder why you'd do it.
Are the walls drylined on a metal furring system or are they just standard plaster onto blockwork?
My go to fitting is Enlite E8's. I'm a pretty firm believer in the fact that an integrated fitting can be designed properly to dissipate heat, rather than trying to cram it all into a gu10 style lamp plugged into a largely empty tin can!
Years back I kitted out a few rentals with the old deep...
I don't think there will be provision for serious space heating.
Each unit will have a small kitchenette and WC, so a 10l undersink would likely satisfy hot water requirements.
If part of the unit gets partitioned off to form an office then you could imagine typical setup of 2kW oil fired...
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