Good evening all

I’ve a house not far from me that likes an evening firepit / bonfire, which when it’s either still or wind blows the wrong way ends up with smoke sucked in through my MVHR, this situation never occurred to me when the wiring was done and the only way to switch it off wothout going into the loft is from the consumer unit but this also isolates another room.
Plus I usually switch it off i house is going to be empty for more than a couple of days. It’d handy to have a more convenient way of turning it off. The simplest would be a wifi controllable switch/ sockett via an app. Plus i’d have the bonus of being able to turn it back on before i get home.

Plenty of options out there, anyone have any experience/ recommendations.

Many thanks phil

Thanks , currently its hardwired into an fcu and i was thinking more along the lines of something like this

https://www.airconcentre.co.uk/products/timeguard-wi-fi-controlled-fused-spur-tuya-edition-fstwifitu?variant=39685254054021&om=13062&gclid=EAIaIQobChMI9tWRlYrJgQMVTeBRCh12TwBvEAQYASABEgKtnfD_BwE

But even sticking a plug on it and using a unit like yours would be cheaper and have more choice.

Thanks

Posted By: ArtiglioThanks , currently its hardwired into an fcu and i was thinking more along the lines of something like

Ah OK. I have a couple of Timeguard FCUs of an older design - just digital timeswitches - and they work fine. One of them failed a few years ago and Timeguard replaced it under warranty without a problem.

WIA , the house has been totally rewired as part of the renovation and the electrician specced what to me seemed like an enormous consumer unit ( i can now see why) , the loft spaces have 13 amp rated circuits in addition to lighting , so i’ve plenty of options.
The vent axia sentinel could have been supplied with wifi control , but as it was a full rewire and everything was open i went for the wired controller, i’ve had a quick read online and don’t immediately see an add on that does anything different to the wired controller. The unit has a built in humidistat which works well on those occasions i forget to hit the boost switches that are wired in for the “wet areas”.
Must be said that whilst i’ve no previous experience of mvhr nor had i lived in the house before it was fitted , i’m happy with how its all turned out , once everything is eventually finished ( there’s a second mvhr system for the other part of the house ( awkward layout and poor planning meant 2 systems was by far the easiest way forward))
I’ll have a play with the various settings if needed. The possible need to switch on and off without accessing the unit was something i overlooked.
This winter should be the first proper test of everything as things are now substantially complete in terms of insulation , heating, etc. Hopefully all the effort will be worthwhile and bills manageable.

Hi again Borpin, you are the guru on all things home automation!

What is the present view on controlling switches over the home wi-fi rather than using 433mhz radio remote control switches?

I have some WiFi controlled devices (kid's multicolour lighting) which are a pain whenever I change ISP and get a new router (despite doing my best to make the new WiFi network look and feel identical) and I think some will stop being supported long before they physically wear out. Whereas the 433mhz stuff just seems to keep working.

Think that's why you'd normally have at least a 20A MCB on a socket circuit, so that the 13A fuses will reliably blow first.

You can get different classes of MCB that trip faster or slower so that you can tweak this, iiuc.

The purpose of the MCB is to react to an unsafe situation (a fault overcurrent in the house wiring) and make it safe. The householder simply plugging in an appliance, should not be enough of an event to create an unsafe situation in the house wiring.

I certainly don't claim to know the regs or understand the consequences of breaking them! Better explanation here
https://learntechnique.com/selectivity-backup-protection-whats-difference/

"Discrimination (Selectivity), is defined in Part 2 Definitions as, ‘Ability of a protective device to operate in preference to another protective device in series’.

"The purpose of selectivity is to isolate a part of an electrical installation with a fault condition from the rest of the installation such that only the protective device located immediately on the supply side of the fault operates to disconnect the supply.

"The traditional means of achieving selectivity are by current or by time.

Current selectivity utilises overload or fault current while time selectivity uses devices with different trip time settings."

"Selectivity is achieved when the pre-arcing I²t of the upstream device is less than the total energy let-through I²t of the downstream device. In plain English – this means that the smaller fuse must complete its operation before the larger fuse reaches its melting point. "

(and theres a lot more after that!).

Posted By: WillInAberdeen20A MCB on a socket circuit,

I think it's normal to have a 32 A MCB because sockets are normally wired on ring mains. They're type B.

The sparky that wired our house told me that the current fashion for metal consumer units was the wrong answer to a problem. The problem was that plastic CUs had been catching fire, so the legal solution was to introduce fireproof metal CUs to keep the fire contained. He said they'd ignored the cause, which was that a previous change in regs had removed the necessity for two screws on each terminal connection. So every poor connection was now likely to start a fire, whereas previously you had to had two failures (or poorly executed tightening of screws) on a single connection before there was a fire risk. So his view was that the sensible move would have been to reverse the previous decision, but when are politics and committees ever sensible?!

Djh /wia, as a landlord who needs electrical installation condition reports EICR, the whole electrical installation situation has got a bit messy. My two blocks of 4 flats each had new 3mphase supplies from the cable in the road and the entire installations were new throughout the entire buildings in 2002/4 installed by a registered electrician to the standard of the day.
Things that were seen as good practice then are no longer seen as such, the daftest move is that with split load boards lighting circuits previously were not protected by RCD or RCBO as it was comsidered that a householder moving round in the dark because a blown bulb tripped the circuit was a greater risk than that presented by lighting circuits. Similarly it used to be common to connect smoke alarm circuits to the lighting circuit as then people couldn’t turn them off without turning off the lights and so would be more inclined to deal with faulty alarms.

The point about going from double to single screw commections is repeated by every electrician i meet and alledgedly the change was the result of pressure from the manufacturers looking to save a few pennies and who at the time demonstrated that single screw terminals tested perfectly well, but no one looked into how they performed a couple of years later after being subjected to thermal changes/ movement. They all say going back to w screw terminals would be far better ( as it would prevent most of the instances of fire) rather than use a metal enclosure to stop the fire spreading, but the industry costs of retooling to change to 2 screws meant it was seen as preferrable to go for cheaper metal enclosures. The entry points to the consumer unit should be protected with intumescent materials.

The EIRC is only valid for 5 years, which passes fast and the regs similarly change just as fast, as a result no one does anything that they really don’t have to for fear of needing yet another change 5 years later.

There are those in the background quietly pushing for EICR’s being required for mortgage and insurance compliance, but this would mean huge disruption for many sales of properties other than relatively new ones , the do,estic electrical industry struggled to cope with the rented sectors when the requirement came in ( and still does on the 5 year renewals) they’d have no chance of covering for al domestic properties.

And if you talk to a fireman they’ll tell you that the risks of a fire from a fixed electrical installation are really quite small and that there’d be much greater benefit to doing something about cheap electrical appliances/ chargers and educating the general public. Being called out to a fire started by someone charging their phone/ laptop/ tablet from an extension block that’s under the pillow is apparently not uncommon. One even saiid that legislating that all charging leads were a 2m minimum length would make a significant difference.

Posted By: Artigliothe industry costs of retooling to change to 2 screws meant it was seen as preferrable to go for cheaper metal enclosures.

Or is it protectionism (metal enclosures shut out the plastic CUs from European manufacturers)?

Posted By: ArtiglioThe simplest would be a wifi controllable switch/ sockett via an app.

Don't have one myself, but maybe take a look at the Shelly Plus 1 - https://shellystore.co.uk/product/shelly-plus-1/

Posted By: djhThe sparky that wired our house told me that the current fashion for metal consumer units was the wrong answer to a problem. The problem was that plastic CUs had been catching fire, so the legal solution was to introduce fireproof metal CUs to keep the fire contained. He said they'd ignored the cause, which was that a previous change in regs had removed the necessity for two screws on each terminal connection. So every poor connection was now likely to start a fire, whereas previously you had to had two failures (or poorly executed tightening of screws) on a single connection before there was a fire risk. So his view was that the sensible move would have been to reverse the previous decision, but when are politics and committees ever sensible?!

I totally agree with your electrician. When the problem of consumer units catching fire, mainly in London came to my attention I was curious enough to do some digging. To my mind a metal consumer unit did not prevent fires just contained it a bit longer. I found a relationship between the number of installs of smart meters with number of fires in consumer units in London. The move to metal consumer units was as a result (as far as I can make out) of pressure from the London fire service. The solution was total anathema to me having worked in an industry where structured problem solving and prevention was the norm to solve issues. Having done quite a bit of electrical work over the years I was aware of changes in materials and equipment. DJH has already mentioned one, the number of terminal screws securing the tails which used to be 2 becoming one but that alone is not sufficient to explain the poor connection that gives rise to overheating and combustion. Over the years the number of strands of wire in meter tails has diminished quite markedly and have become thicker. The tails are not as flexible and can be awkward to get a good fix in the CU terminals. The copper does not compress as much so making a poorer contact (There has thankfully been a move to more flexible tails with increased number of strands though not anywhere like some 30/40 years ago, but at extra expense). So where does the smart meters come into the equation. The meter installers are not trained electricians they have been trained to work safely and change the meter. This means juggling with stiff meter tails that wag about and work loose in the CU. They are not permitted to access the CU tails connection (only the meter end) which perhaps a trained electrician would the CU connection. There may well be other factors also involved such possibility as an increased occupancy of premises putting an extra load on the CU.

PIH - revor explains it well, but as ever it gets more complicated in the real world, different electricians see things different ways and can interpret things in different ways. Getting parts to improve an old consumer unit ( eg it’s suggested you protect the lighting circuit with rcd/rcbo, which whilst not having it doesn’t make the installation unsatisfactory,is put down as a recommendation by the engineer) may not be possible and the electrician won’t fit secondhand parts ( the auction site is a good source ) you’re then left with either a full consumer unit replacement or doing nothing.
I had a flat that at some point prior to my buying it had had a radial piggy backed to a ring circuit, no one had an orignal new breaker for the existing consumer unit that had plenty of space , i could get a secondhand one, but electrician wouldn’t fit it, i could have but then he wouldn’t retest and sign it off. So i’d have to risk getting another electrician and see what they picked up. As a result i end up with a new consumer unit and a £650 bill.

In other flats , i have different recommendations which can be “left on record” if i were to spend the money and get it changed , i run the risk of it also being unsatisfactory in 10 years , so better to only do what you really have to. Onviously there are those who have greater risk aversion and do everything. I take the view that my installations are safer than anything more than 20 years old and untested and i’ve complied with the legislation.

Previously landlords only had the duty to ensure the electrical systems were safe, for me that meant using a basic socket test device, checking the trips in the consumer unit and a walk round the flat checking the sockets and faceplates. It was no uncommon to find that overseas tenants had forced something into the earth connector to enable them to get a 2 pin plug into the socket, sockets that had overheatet and brocken faceplates. The worst thing i found was a tenant who’d got another fridge feezer, plugged both into an extension block , wrapped the excess cable round an aluminium walking stick that stood between the two fridge freezers and then filled the rest of the space between them with old carriers bags and packaging. They had no comprehension of how dangerous it was and felt i was being unreasonable when i unplugged it all.

Landlords with the freehold of flats, also have the common area installation to get tested , which as it is deemed a commercial installation doesn’t fall under the training of all electricians. Similarly if you have a hardwired fire alarm system that covers the common areas and often a heat detector just inside each flat door ( not a requirement under building regs in most buildings, but i had installed as i felt that no protection for the common areas or flats that may be unoccupied was not a good idea, means a 6 monthly test and as (again) it’s deemed commercial , technically you are meant to have a weekly test of random call points and the alarm bells, which cost aside is hardly reasonable for a domestic setting in the days of shift working. Fortunately it’s something to which a blind eye is turned or else people would just remove the systems and rely on the heat/ smoke alarms required in each flat.

WIA - your post goes over my head , if I haven’t understood it before the sparky is back , i’ll ask him to explain it.

DJH, regarding the circuit , i had the same understanding as you, however a ring main is protected by a 30 amp fuse/breaker and a radial spur from the circuit will usually only have a single run of 2.5mm cable and so is only rated at 15 amps, leaving the spur potentially at risk of overheating. So the spur would need its own fuse. However in my case the radial came from the consumer unit and had been connected to the same breaker as the ring power circuit, this is what the electrician called “piggy backing”.

But must be said whilst i try to understand what is done and why, the detail is why i use a proper electrician these days it’s all way beyond diy stuff for me.

As for the lighting circuits, a few of the flats have a bedroom up a flight of stairs, i’ll take a look next time i’m in one and see if its wired as you suggest, the other flats are small and all on one level so i doubt they’d have split lighting circuits. They were done 2002/4 so not sure what the norm was then. I’d hazard a guess most people have a mobile by their bed and that would be there torch if needed.

Spurs off a 'ring final' circuit are only allowed to go off to one socket, to avoid overloading the single cable run, as Artiglio said. A radial needs a lower rated MCB eg 20A, or a FCU off the ring.

Lighting circuits are still sized on the assumption that all the fittings are 100W incandescent (0.4A), so each 6A lighting circuit can only serve so many rooms. Now that everyone uses LEDs, there shouldn't be any problems with a single lighting circuit covering a big house, if the regs moved on..!

You didn't say where you're quoting that from - Google thinks from a DIY website and an orange DIY shop, which (with due respect to them) are not very authoritative sources! 12 LED fittings add up to about 1A.

If it did come from somewhere official, then change isn't a problem,

if the regs moved on..!

Edit - the you-can-do-it-shop's article explains their opinion is based on customers using "a 100W bulb at every outlet". It's been many years since they stopped selling 100W bulbs in there!

Indeed wiring should cater for the possible. We use GU10 lighting, so I think the worst it is possible to do is 50 W per socket.

My point with the unattributed quotes was simply that having two lighting circuits is indeed a common, and IMHO sensible, arrangement. I would not like to live somewhere with only a single lighting circuit.