using wifi plugs for heating control..regs question from a Gas man!.

[333rocky333]

,,,

 

[333rocky333]

Can you provide me with an example of where I would find a voltage exceeding 230V nominal to earth on a standard UK mains supply please.

Not knowingly encountered it personally but I believe Spark123 once said on here it is sometimes found on Discharge lighting.
You do a lot of lighting is it something you have encountered RF

 

[blubs]

wow!! I have no idea what they are on about!? 230v??,,

so a double socket connected to adjacent 3a spur and labelled as such, and for 'heating controls only' would be ok by UK regs??

@Harry Bloomfield, thanks for your marvellous reply, and solution to the y plan extra wire issue,
As a seasoned heating engineer I am disgusted at the reliability and lack of over-ride on modern controls, about 20% of the vans you see are off to get a switch wire to a boiler!!, often just changing AA batteries or re pairing, (binding!) expensive rubbish..
These plugs sandwhich between a plug labelled "H/W" , or "heating", and a plug socket, 95% or users would understand that they could simply remove the wifi plug and use the socket switch to turn these essential things back on and off again when inevitably they fail, but £7.50 next day from amozon to replace!, as opposed to £200 for an engineer to change a honeywell programmer!! game changer...
so a socket connected to adjacent 3a spur and labelled as such, and for 'heating controls only' would be ok by UK regs??

 

[Harry Bloomfield]

so a socket connected to adjacent 3a spur and labelled as such, and for 'heating controls only' would be ok by UK regs??

As I understand it - YES!

..and no one has responded to the contrary, as they would usually do when wrong advice is offered. Go for it!

 

[ericmark]

If one looks at a S plan it seems the motorised valve isolates the boiler supply from the valve supply, this is not the case with the Y Plan, so with the S Plan you should be able to drive the valve completely independently from the grey and orange wires which work the boiler.

We have the same with a thermostat, with no volt contacts the supply to drive thermostat should be independent to supply to motorised valve or boiler.

But look at a mid position valve

and it is clear there is no isolation between the motor supply and the output to the orange wire, and here we are looking at Honeywell, not all makes are the same, so be it the motorised valve or the wall thermostat the big question is would a like for like replacement always have the same internal wiring? Is there a version which does not isolate?

The question has raised its head many times, should you plan for what some one may do in the future? Be it change a 60 watt tungsten bulb for a 10 watt LED and the resulting impact on a dimmer switch, or part of a central heating system. We see it again and again, some one thinking they are making an improvement splits the down stairs and upstairs lighting, and as a result we have a borrowed neutral. (really a borrowed line)

@stem has pointed out most manufacturers say all the low voltage (230 VAC) supplies should come from same source, not well written, as very few houses have multi-230 volt supplies, they one assume mean the same circuit, i.e. uses the same overload device, so if there is a fuse inside the boiler then supply would have to come from the boiler, and I think that is not really their intention, so we again come down to the English used in instruction manuals and wiring regulations rather than the actual electrics involved.

So as a system designer you can produce a circuit diagram so anyone who follows can see exactly how it is wired, this is what I did, so this is one of the plans I made for my own house, however even that is flawed, as I kept altering it, and now can't remember which version I used, but time to work on central heating is the summer, so time to correct errors without risk of freezing.

However if you make an as built plan of your heating, then you or others can study it and see errors or prevent errors in the future. So as long as there is an as built plan in the boiler so anyone in the future can see how wired I see no real problem. However been in this house now 18 months, yesterday say some thing in the boiler, and on retrieving it, found it was boiler instructions, with mothers bosch boiler there was a place in the panel designed to hold the paperwork, but this oil fired bosch boiler does not have a built in pocket for paperwork, so I was unaware it existed.

 

[333rocky333]

As I understand it - YES!

..and no one has responded to the contrary, as they would usually do when wrong advice is offered. Go for it!

I quess you could use an "ISOLATE ALL SUPPLIES BEFORE SERVICING" label if you have concerns

514.11.1 does ask for a warning notice, where there are live parts which are not capable of being isolated by a single device, but is not specific on the label needed.
If there is no risk of confusion on how to isolate your device from the two supplies then the risk is reduced and the label can be less informative.
The Regs, not valid to you are more detailed regarding multiple supply's to the premises, i.e. generators, solar etc and that label is more detailed and a Template is specified .

 

[MattChan]

If you were doing this as a commercial product which I know you aren't the standard you would need to comply to is probably EN60730.

The relevant parts are probably EN60730-1; EN60730-2-7; EN60730-2-9.

Available from Estonian Standards at a snip of the price of BSI
https://www.evs.ee/en/evs-en-iec-60730-2-7-2020

Not many labs in the UK test to this standard, and it was relatively expensive to do last time I bought one to market

For the WiFi element you would then need to comply with RED (radio equipment directive) too.

Looking at the DoC or CoC for any COTS product will give you the list of standards that that device was designed against. Reviewing them can then help make a home brew solution closer to commercial quality.

My ramblings should put everyone to sleep

 

[Harry Bloomfield]

So as a system designer you can produce a circuit diagram so anyone who follows can see exactly how it is wired, this is what I did, so this is one of the plans I made for my own house, however even that is flawed, as I kept altering it, and now can't remember which version I used, but time to work on central heating is the summer, so time to correct errors without risk of freezing.

I did that, when my CH was first installed, for my own fault finding benefit - back in the 80's. I haven't bothered since the last time I upgraded it with full set of Vaillant controls, because it is all so well marked up and so obvious. During the same major refurb I did a large scale drawing of the property, showing the boundaries, where the drains ran, cold water supply pipe, gas and electric cables.

 

[bernardgreen]

make a home brew solution closer to commercial quality.

or maybe better than commercial quality....

 

[ericmark]

I would since December 2020 the job has been completed. As far a regulations and laws go, it seems you need a degree in English. Take the word supply and circuit as an example. We have a definition for circuit in BS 7671 but supply it says "Supplier (see Distributor)." so it seems to my mind 99% of homes have a single supply, but that supply is split into many circuits. As to if a RCD forms a circuit is up for debate, but I would say it does.

So the next is manufacturers instructions, which need to be taken into consideration. @stem published four examples of manufacturers stipulating supply types this

but these

makes leaves no room for debate it does not even allow a plug and socket, the first one Worcester Bosch say what type of RCD must be used, and so how much consideration should be given to manufacturers instructions? Should a heating engineer tasked with fitting that Worcester Bosch tell the customer he needs his type AC RCD swapping for a type A, and I see no reason why a boiler should not be plugged in with standard 13A plug.

Today we have to it seems use common sense, it may say

“consumer’s installation” means the electric lines situated upon the consumer’s side of the supply terminals together with any equipment permanently connected or intended to be permanently connected thereto on that side;

so that means some one doing an EICR needs to check the electrical connections to a boiler, but I would only remove boiler covers to check if other things found pointed to a likely problem.

My central heating has 10 electrical supplies, but 9 of them are pairs of AA cells, I see no problem with that. With my Nest Gen 3 thermostat, it is supplied from the heat link, but having it supplied from a USB socket or adaptor I see as no problem, and that is no different to using a thermostat with the power supply built in to it, so having a volt free thermostat supplied from a different plug or FCU to the boiler is not a problem, the problem arises if not volt free.

We go to collage as an apprentice and our lecturers tell us what should be done, then some thing changes, be it a AGM battery, a modulating boiler, or the internet, and the result is what we were told all though years ago is no longer true. And we need to move with the times.

 

[davelx]

[quote}leaves no room for debate it does not even allow a plug and socket[/quote]

A 13A fused plug and DP switched socket IS a fused double pole isolator. The rest is just how the connections are made. In fact, the socket doesn't even need to be switched - pulling the plug out isolates just as (arguably more) effectively as the switch in a DP FCU.