puntloos

Switchable power to every room?

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On paper it sounds cool: Having a central power closet, with one power line going to each room so for each room you can both switch on/off the entire room and also know what the room in question is consuming. ("No dad, I'm not playing computer games anymore.." -uh huh. And why does it show 400W for one reading light?)

 

But, there's a few downsides:
 

1/ Probably a few devices in the room need to stay powered. Networking router, smoke alarm maybe? 

but more importantly:

2/ Most switches I'm aware of only switch the usual 3000W - eg this one - https://www.itead.cc/sonoff-pow-r2.html - handles 240*15=3600W max. I don't like the idea that plugging in a vacuum and a hairdryer and a few bits and bobs might just overload it. (I guess I can build clever smarthome functionality to switch off the room if it hits 3500.. but..)

 

How are classic houses built? Is each socket separately capable of sustaining 3500W? Or are most sockets in a room linked to one "3500W max" line anyway?

Would you perhaps create one specific "power" socket and the rest standard?

What about the lights? Separate circuit?

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Our house has what are becoming considered "old fashioned" ring finals for the sockets, we have three, one upstairs and 2 downstairs.

 

Lights are one upstairs, one downstairs.

 

Then there are separate circuits for ovens, hob, smoke alarms,  ASHP, immersion heater, treatment plant, provision for panel heaters (unused) etc.

 

If you opt for separate room circuits, why do you want them remotely switched?  When will you ever use that?  Why not a decent sized consumer unit and a lighting circuit and radial socket circuit for each room?  Why make it more complicated?

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36 minutes ago, puntloos said:

How are classic houses built? Is each socket separately capable of sustaining 3500W? Or are most sockets in a room linked to one "3500W max" line anyway?

Would you perhaps create one specific "power" socket and the rest standard?

There is a thing called diversity, can't remember the exact formula (someone else will) but for any given circuit there is an assumption that one socket will have a full load on it, and subsequent sockets have a part load.

 

New vacuum cleaners are currently limited to 1600 W.

Edited by SteamyTea

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Although diversity rules are used when determining things like the maximum load, the over-riding principle is that the cable is always protected by an over-current device that will trip at a lower current than the maximum rating of the cable (accepting that ring finals are slightly oddball - two ~27 A capable cables run effectively in parallel and normally protected by a 32 A over-current protection device).

 

This means that if you run a radial power circuit in 2.5mm² T&E, then you would most probably protect that circuit with a 20 A over-current protection device.  It doesn't really matter how many 13 A outlets there are on the circuit (in theory) as the circuit is protected such that the cable cannot be overloaded.

 

The same goes for any other radial circuit, the over-current protection device is rated to protect the cable, and so prevents the circuit being overloaded by tripping out.  For example, we have a 20 A protected radial, run in 2.5mm² T&E, that supplies power to the heating system.  That circuit has the ASHP, UFH, programmer, thermostats and a single 13 A utility outlet (just somewhere handy in the cupboard to plug a light in to see the UFH stuff) connected to it.  I could plug a 2.5 kW electric heater into that 13 A outlet, and turn on the ASHP, UFH etc, which could add maybe another 2.5 kW of load, so overloading the circuit.  If this happened for long enough the RCBO protecting that circuit would just trip to protect the cable from overheating.

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To solve the 3kW limit, you can be a contactor on each circuit - basically a big old mains operated relay. You'd use the sonoff or whatever to control that.

I'm going to do this on a few specific circuits (110V transformer for my US appliances, garage bench sockets, perhaps the outdoor sockets) but in general I really agree with your other point that the "room" is the wrong unit of control for sockets. (Unlike lighting circuits)

 

Another option recommended by a friend from the BBC is do what they do in control rooms and have 2 circuits to every socket. "12hour" and "24 hour". The 12h circuit gets shutoff out of office hours.

But then why not run a 3rd circuit for battery-backed 24h too? And before you know if the house looks like  https://metro.co.uk/2019/11/03/house-worth-1350000-enough-plug-sockets-everyone-street-11033568/

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Like @ProDave I can't really see the real-world usefulness of this.

 

In terms of remote switching, a room-by-room basis could well be too blunt. Also worth bearing in mind there are increasing numbers of devices that have some sort of shutdown procedure and don't take kindly to a hard power off. So you may still have to go into the rooms to shut down before you can use your fancy remote isolator anyway.

 

The only thing I can think of would be for powering off the house when you go away but in that case again you might want to have some of those random room/desk lamp/TV&radio controllers to make it look occupied so a global kill switch not that handy. And does it happen often enough to justify the cost/future maintenance potential etc?

 

Likewise per-room data logging might not really tell you much (unless e.g. to show a lodger or older child how much they're using, or support an expenses/tax claim for homeworking). There's also easier ways to do that e.g. with current transformers.

 

Per-outlet switching and monitoring like a fully functional building management system might be useful but at much higher cost. But possibly one of those where saving a little ones halfway house is actually a waste of money.

 

If it was me I'd organise the electrics based on traditional concerns (load distribution, what fails if the circuit trips, can you still see your way to the fuseboard, what's logical and easy to understand in terms of isolating for maintenance). 

 

And then add a couple of smart sockets/inline meters/whatever for appliances and outlets you're particularly interested in.

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All that said, having just got poked in the eye by a pine needle for the umpteenth time I would recommend a smart socket for your Christmas tree lights!

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Honestly, I my point about 'switching off the kid's room at 8pm' was mostly joking, I doubt Id want to be that parent.

I think indeed my main reason would be for safety (holiday) reasons, as well as indeed monitoring overall power usage.

 

Perhaps it's less useful than I imagined.. and indeed it's a fair point that while not necessarily damaging, most equipment isn't really meant to be hard-power-cut. 

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Monitoring power per circuit can make sense.  Helps pinpoint where things have been left on in error, etc.  Interrupting power, well, you have a CU for that.

 

Rgds

 

Damon

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My cheap energy monitor suddenly started giving a higher than expected daily total.

Was my fridge stuck on due to loosing gas.

Usually fairly simple to pinpoint odd usage patterns, it showed my immersion heater failing. But then do did like warm water.

Biggest problem with energy monitoring us that you have to check on it. And then do something about it.

 

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Had a frantic couple of days [¹] earlier in the month trying to work out why my background energy consumption had increased from about 22 W to about 30 W. Tried switching all the circuits off and unplugging things. I was just on the point of popping up to my site to get my generator so I could run my CurrentCost meter “off-grid” to make sure it was not itself consuming the extra power when I thought to check the alkaline cells in the sensor box (current transformer clipped round a meter tail). Indeed, they were down to 1 volt each. New cells, all reading sensibly again.

 

In retrospect I should have noticed the apparent power consumption of the shower creeping up from a bit over 7 kW throughout November.

 

[¹] I exaggerate slightly - more like dabbing at the problem on and off for a week or so.

nov-dec-power.png

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1 hour ago, Ed Davies said:

CurrentCost meter

 

1 hour ago, Ed Davies said:

New cells, all reading sensibly again

I had a similar problem earlier in the year.  But it just went to no readings.

Bit of a problem because the batteries can last years, think I once I changed (the white optical sensor) was about 7 or 8 years old.

 

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Exactly what I’m having 

One radial socket ring per room and one ‘lighting’ ring . Makes isolation and fault finding easier . Bit more work , bit more cable but worth it 

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You could fit z wave sockets to each room . You can then turn on/off remotely and also get consumption use ...

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6 minutes ago, dpmiller said:

what's a radial ring?

 

A figment of a confused imagination. As is a “lighting ring” (usually).

 

A final circuit is typically either a radial or a ring. Rings are so common though that many refer, incorrectly and potentially confusingly, to all circuits as rings, even when they're not. E.g., lighting circuits are typically radials but often referred to as rings.

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20 minutes ago, Ed Davies said:

 

A figment of a confused imagination. As is a “lighting ring” (usually).

 

A final circuit is typically either a radial or a ring. Rings are so common though that many refer, incorrectly and potentially confusingly, to all circuits as rings, even when they're not. E.g., lighting circuits are typically radials but often referred to as rings.

Exactly what my electrician said .

So ; I’m doing it correctly but terminology might be wrong ! 😂😎

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1 hour ago, dpmiller said:

what's a radial ring?

Many of us have come across the "lollipop" circuit, which you won't find in any manual.  Typically a redundant 6mm radial to a kitchen, with a mini ring final stuck on the end.

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43 minutes ago, ProDave said:

Many of us have come across the "lollipop" circuit, which you won't find in any manual.  Typically a redundant 6mm radial to a kitchen, with a mini ring final stuck on the end.

 

yep, that's what i thought @pocster was talking about. But when he mentioned lighting too...

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@ProDave how do you look after a lollipop on the EIC?  Just ignore the "stick" and pretend it's a normal ring final?

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59 minutes ago, dpmiller said:

@ProDave how do you look after a lollipop on the EIC?  Just ignore the "stick" and pretend it's a normal ring final?

Well you can measure the  impedance of each of the conductors of the ring and enter that, and you can measure Zs and enter that.  There is nowhere to say it is anything other than a standard ring.  Your Zs may be a bit higher than R1+R2 would suggest.

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Just make a note of it in the paperwork, I see no problem with it as Dave says as long as Zs is ok.

 

like the old houses that had a separate Wylex board for the kitchen, when kitchens became fashionable 😀

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I was able to turn my sons bedroom off which was good, also set the broadband to disconnect all his devices at a set time.

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I’ve put each of my 4 kids rooms ( well every room except the kitchen and utility ) on radial circuits and their own RCBO’s. Lighting on their own circuits and smokes on their own circuits.


CAT6 PoE switch is on its own radial, which also services hall / landing / cleaning / air wick sockets, and at a set time I can just drop the LAN and WiFi off to everything other than the downstairs TVs / set top boxes etc, and any time my kids offer up a bit of ‘confrontation’ the mere threat of my finger waving over the little test button on the RCBO makes the kids concentrate much more intensely on what I’m saying. 
I call it Parental Override. Works like a dream.

 

I’ve hooked up with a sparky I met about 7 years ago  ( @Bitpipe used him ) and he’s been giving me some ideas. Current projects will now be getting 20a rings instead of the 20a radials that I’ve been using previously. Made a lot more sense once the pros snd cons of both were discussed. 
2 heads better than one and all that jazz. 

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56 minutes ago, Nickfromwales said:

I’ve put each of my 4 kids rooms

5 now 

 

56 minutes ago, Nickfromwales said:

I’ve hooked up with a sparky

Swinger !!!

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