Alan Ambrose

I guess the tactic of intelligently heating the slab with UFH, used by a few people here on BH, is the simplest version of this?

>>> anyone self building from applying for a CIL exemption if they have a holiday home Interesting question. I'm obviously trying to not fall accidentally foul of the rules as the penalty is large. https://www.gov.uk/guidance/community-infrastructure-levy#para082 Individuals benefiting from the exemption must own the property and occupy it as their principal residence for a minimum of 3 years after the work is completed. Now it does say 'sole or main residence' in the actual act: https://www.legislation.gov.uk/uksi/2010/948/regulation/54A and the form to be submitted at the end is this: https://ecab.planningportal.co.uk/uploads/1app/forms/form_7_self_build_part_2_exemption_claim.pdf and says 'sole or main residence' again, so maybe having a holiday home or even a rental property isn't a problem. But nothing about the period where you may have two homes temporarily while you're selling the old one.

Ah so assuming you have no other pressing matters (e.g. mortgages) you could potentially be living in the new place, paying council tax etc, but hold off on the completion cert until your old place has sold? Often the question here on BH is ‘how quick can I get my cert…

>>> is the planning permission for self-build housing? There's a couple of plots near me that have been advertised as self-build plots that are not selling and I wondered why they didn't then agree with the LPA to sell them as standard plots. As to the OP's question - my understanding is that the CIL self-build legislation is fairly vague and thus open to interpretation by your LPA (I've never read all the way through it)). I think the only option might be to trawl (yourself or via a lawyer) through the legislation or simply ask your LPA. In any event if your LPA says 'no', regardless of the legislation, I suspect you're not going to court and will have to suck it up. Worth asking though.

OK so you're near the completion of your self-build and ready to move in. You've avoided the huge CIL levy payment by correcting filing the CIL self-build paperwork at the right time. You put your old house on the market, expecting it to take anywhere between 3-12 months to complete as is normal. But CIL doesn't allow you to claim the self-build exemption if you have two homes - which you will have from the moment you get BC final sign-off on your new one until you sell your old one. Strictly, 'you're breaking the rules'. Is there any known provision for a grace period to allow for this practicality?

@SteamyTea - that's below the belt, bothering us with the data dammit...

I think 5m is, in practice, an ambition rather than a hard rule. What's the best you can do?

Well if the vermin risk is low: 99+% of UK houses use pinned T&E only so that's an option. But you'll of course need to agree any method with your sparky. Discuss the many options with him or her and go from there? Be interesting to know what you jointly decide.

I appreciate you would like this solved quick and without too much fuss …. But … I think it depends on how bad the vermin problem is, how difficult it would be to take up the floor again to repair vermin damage, and how difficult it is to wire all the way back to the CU. If your electrician has suggested plastic conduit then it indicates they think the vermin risk is high and it won’t be so easy to take the floors up again. So, if you’re not so bothered by the vermin risk or the floor is just screwed down and easy-ish to lift - then just run standard T&E without conduit as normal. (Or maybe if you’ll be moving in a couple of years anyway.) If the floor is not coming up again for another 80 years or the vermin risk is high or you’re planning to live there for a long time, then I would go a bit off-piste and run singles in metal flex conduit without any sharp bends. Then (a) it will be easy to pull new cables in 80-years time and (b) the vermin will end up with blunt teeth. Metal flex isn’t crazy expensive either. I’ve used 25mm OD / 20mm ID in a domestic context and would suggest that if you have room. You may find one size down will work, but you’ll want to check ‘pullability’. Check that the metal flex end glands work with your back boxes OK. Sure, if you can get all the way back to the CU without too much difficulty then radial if you prefer, but I don’t think it’s the major issue here. If you go for the non-vermin proof solution you might consider an AFDD in the CU to mitigate fire risk a bit. Oh and a flexi for each run of course - there’s no Y connector that will help unfortunately.

So apologies to @Mr Blobby, but having never done it before, this is why I think I'll get a better result on my windows than the average window fitter.

>>> do what they always do Which is bodge it in the hole roughly square and then fill all the gap with crazy foam?

I seem to remember Planning Docs - presumably so they can check that the building is legit and that the costs & materials make some kind of sense for the dwelling. The latter is just my supposition though - knowing central government, it is even more likely there are no checks at all and it's just a tick box item for them

It looks like a mis-measurement or mis-manufacture to me.

>>> I’ll cross that bridge You're planning a bridge too ?

As a low priority I might email your planners, explain the detail and ask them what they want you to do. They should be perfectly reasonable as you have acted in a sensible and cautious way. In the worse case, they might ask you to apply for a retrospective amendment to your original permission or alternatively for a 'lawful development certificate'. I would present them with the problem though and follow their solution if any. They probably won't care much. You might only care when you come to sell, and then only if it is sometime soon-ish i.e. before the 4 year enforcement period has passed.

>>> i haven't fitted any of those LED strips yet! You can jury-rig a strip to measure it or just estimate: I suggest the equivalent of 10 x 60W old-style bulbs would allow you 'to illuminate 'luxuriously' during a power cut'. That's about 60W equivalent total of LED lighting. 10 hours of that would be 0.6 kWh, which at 12V is 50Ah - so one typical LA battery. Plus whatever the Loxone rig takes when it's idle, which could be a non-trivial bit. Plan to use one battery and add more if you really need it later?

>>> Still looking for a better option ideally din rail mounted. Take a look here: https://uk.rs-online.com/web/c/relays-signal-conditioning/relays/timer-relays/?pn=1&applied-dimensions=4294883333,4292117068,4294571726&sortBy=P_breakPrice1&sortType=ASC RS won't be the cheapest, but most of the stuff they sell is professional quality. You'll probably need to apply a few more filter criteria, check the datasheet etc to make sure it has the continuous cycling function you want. In particular, check the contacts are man enough for the job ('max current') - suggest 3A min and beefier if you want long life.

There was some discussion on BH on this subject recently, we’re at about 190W background in our place. One way to delve into this further is to use a current clamp meter on the main incomer (one cable only, either line or neutral) and switch individual things on or off.

OK ta, will give those a try. I also found SealedUnitsOnline aka Ipswich glass. They get mixed reviews, but after calling into their offices and talking to one of their counter guys, I was a bit re-assured.

~1900m2 !

>>> the length of the diamond cutting edge (and hence friction) is also proportional to diameter, hence the square I thought this, but forgot to write it, duh: Imagine a core drill with one tooth (or diamond grain) which can be magically set at any radius. The torque required to rotate the bit (or equivalently the torque required to hold the drill) will be proportional to the set radius of the drill / cut. Next, imagine you can magically add more teeth to fill the core drill to make it a full circle. The torque required to rotate the core drill will be proportional to the number of teeth. And the number of teeth will again be proportional to the radius. So, the total torque for a normal core drill will be proportional to the radius squared. Of course, there are other factors too. The above will be correct assuming we keep the downward pressure per tooth constant - which means we need to ramp the total bearing pressure linearly with radius. For conditions within a reasonable operating range, you can imagine that the torque required will also be a linear-ish function of the bearing pressure per tooth and also roughly proportional to drill rpm.

Will this work? One evening, adjust your lighting to your preferred minimum as though you were having a power cut. Measure the current / power draw. You can get a similar figure during daylight too if you need any lights on then. That’ll give you the max realistic power draw you need to cope. Then you can make a little table for run time vs. battery capacity. Check the number of hours between sunset to bedtime on the shortest day and the longest. Those few numbers should allow you to make the trade off you need.

Do you need every channel of every LED strip turned to full brightness in a power cut? A LED takes about 9 times less power than an old fashioned filament bulb. So your 960W of backup LED power is equivalent to about 190 old fashioned 60W bulbs. That’s a lot of lighting to use in a power cut . Maybe just pick a few essential lights for that not very common ‘use case’?

>>> It is force (N, mass x acceleration) at a distance (m, metre). So Torque = Nm So basically, the longer the handle, the more torque can be applied. <<< True, but the length of the diamond cutting edge (and hence friction) is also proportional to diameter, hence the square.

Well we're in the wrong forum for the detailed behaviour of filament bulbs, fuses and MCBs (try eevblog or some of the more inquisitive physics/electrical youtube channels). Here's the short answer: The bulb is normally ~40W i.e. 0.2A i.e. not much. This is a total guess on my part, but I am going to suggest that the current spiked to, say, 10-30A for, say, 100ms. If you had current clamp and an oscilloscope, and could repeat the experiment at will, you would be able to see the fast spike and estimate the maximum current amplitude. That spike was enough to blow the fuse and trip the trip. The fuse blew in say 800ms, but while that was going on the MCB tripped - yes, the MCB shut off the current, but the fuse was already red hot by that time. There's endless detail (as there is in any subject if you dig deep enough) but here's a bit more: https://physics.stackexchange.com/questions/341134/how-to-calculate-melting-time-of-a-fuse https://library.e.abb.com/public/114371fcc8e0456096db42d614bead67/2CDC400002D0201_view.pdf >>> I'm trying for an analogy in chain terms but can't think of one. OK this: suppose you have a chain with a breaking load of 10T. There are two weak links of various sorts, one 1T, one 0.5T. You suddenly drop a 500T load on the end of the chain (remembering to stand well back). Everything flys apart, both weak links shatter with the shock load and two bits of the rest of the chain shoot past your ears dangerously (the final part is still secured to the ceiling). Theoretically the main chain would break too but the very short time before the weak links break means that there isn't any time to do the work (force x time) to make the main chain break before the weak links give way and remove the force. In this case, the analogy for the main chain is the mains cable. Now, be happy that this worked as it should ... because you didn't melt any mains cable and you didn't have a fire. I think that mice don't nibble cable so much but rats and squirrels like to sharpen their teeth on everything. So best to remove the problem promptly.