Home automation control of 240 volt devices?

Discussion in 'Computers, Hardware, and Operating Systems' started by AC0GT, Sep 4, 2018.

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  1. AC0GT

    AC0GT Ham Member QRZ Page

    I'm helping my brother find a way to turn a 240 volt device on and off through the use of his smartphone, home automation devices, or computer. If it matters the intended device in question is an air conditioner but if we all want to keep this amateur radio related then pretend the device is a legal limit amplifier or heavy duty battery charger.

    For some background I'll explain further. My brother has a detached garage that was intended to be a workshop of sorts before he had a wife and kids. Since then it's turned into a playhouse. Since it was intended as a workshop it's got plenty of outlets along one wall for where a work bench would have been, a 30 amp 240 volt outlet intended for a welder in one corner, and in another corner a 20 amp 240 volt outlet intended for a large table saw. The shed is insulated well and so he's been able to keep it warm on all but the coldest days with a couple 240 volt heaters, a smaller one on the "table saw" circuit and a larger on the "welder" circuit. Through the summer he's able to keep it cool and dry enough for comfort on most days with a standard 15 amp 120 volt air conditioner.

    After a shockingly large electric bill one month from leaving something on he bought some Belkin Wemo remote control outlets (the same as or similar to this one: https://www.belkin.com/us/p/P-F7C027/ ) so he can check if he left something on from an app on his phone and he can voice control them with one of those Google home automation devices. He still has to check on the 240 volt heaters manually but at least he can control the 120 volt air conditioner and some cheap 120 volt heaters. He'd like to be able to get a larger air conditioner because what he has can't keep up, and what he's got is already the max size he could get on 120 volt. The 240 volt heaters he'd like to control as well, as the smaller heaters can't keep up on colder days, and he's paranoid about leaving them running while he's not there.

    I already ruled out some options. He doesn't want to run any new wires. It's a garage with surface mounted conduit for wiring so we can get at most everything but no one wants to try to take that apart, run new wires, and put it back together. He's willing to do some pretty minor alterations if he must but there is a line based on funds and approval from the "boss". Also ruled out are many "hacks" I offered to construct to control the 240 volt circuit from a 120 volt Wemo swtitch. The "boss" doesn't want her children playing around something that's some kind of high school science project. I can understand as it appears she's seen some of my previous "works of art".

    What I'd like to find, but have been unable to locate just yet, is a Google Home compatible 240 volt switch. It doesn't have to be Google Home but it does have to be automated by a popular home automation system. My brother has played with home automation from Google, Amazon, and Apple, and so he can switch to whatever works.

    Failing that I'm thinking of using similar devices to that Wemo intended for use outside the USA. In many nations the standard voltage is 240 volt and there are off the shelf adapters for making them work on USA standard plugs. This should make it pass inspections. To make things neater and safer it might be nice to find a foreign outlet that fits in a standard USA electrical box, or can be somehow connected safely to USA standard conduit. I believe I found things like this once but I didn't make proper note of it and lost where I found them, but I can probably find them again.

    I'm thinking that there's enough readers here that have tried similar projects that someone might have some good advice. I'm not really into trying to do this home automation stuff but I'm beginning to see this as more than a novelty. If I can get this to work for him then I have some similar things I'd consider for myself.
  2. KS2G

    KS2G Subscriber QRZ Page

    Perhaps this?
    BOSS 220 Smart Plug
    The 220 V Smart Plug is rated for 20 amps and can control all your heavy 220V loads such as PTACs, pumps and wall and ceiling electric heaters.
  3. WB2LBV

    WB2LBV Ham Member QRZ Page

  4. CX3CP

    CX3CP Ham Member QRZ Page

  5. AC0GT

    AC0GT Ham Member QRZ Page

    That looks about right. The price is a bit high but maybe that's just what they cost. Doing a bit more surfing I found a competitor.

    The Boss Control device is for 20 amp loads which is great for one of the circuits in question. The other is a 30 amp circuit but as I recall the circuit was originally wired as a 40 or 50 amp circuit but the breaker and outlet were replaced to fit the heaters he was using. At first a NEMA 10-30 outlet was put in there for an old heater from a garage sale, but when that died he got a new heater of the same output that used a NEMA 6-30 plug and the outlet replaced again. He still has the original outlet and breaker and so we could put those back and use the Wallflower brand device. An adapter from the 14-50 plug to whatever he might need for a heater or air conditioner do seem to be available, again not cheap but they exist.

    In other words, one outlet is wired such that we have options on the size and style of plug. It's got wire heavy enough for at least 40 amps and has neutral and ground. The other outlet (that I've been calling the "table saw" circuit) has only two hot and ground, no neutral, and the wire is sized for only 20 amps. I remember the lack of a neutral wire being an issue for some reason, but I'm not sure on the details. I don't recall seeing an air conditioner or heater that needs a neutral. Maybe he was looking at some kind of heater/AC combined unit that used the neutral for something.

    Oh, and one other "nice to have" on this is a means to control the temperature from his phone. I did some research on this and found devices that offered this but only for those kinds of units that had an infrared remote. The device simply mimicked the key presses on the remotes, they did no temperature sensing or switching of their own. That might have to do. He hasn't bought a bigger AC unit yet so he can simply find one with an infrared remote, which seems like standard equipment anyway.
  6. AC0GT

    AC0GT Ham Member QRZ Page

    Neither of those would pass inspection from the "boss". The device should simply plug in like those Wemo lamp dimmer wall warts. We did some math and figured out that having to get an electrical box, transformer, relays, wires, and all that other stuff to construct something would get expensive quickly. Not only would that not save much money and gain little in features but the "boss" doesn't want something little kid fingers could get into.

    What might be acceptable is a baseboard heater controller that could be fitted to a standard electrical box, but the ones I've seen are "wimpy" and are rated for only 15 amps. Even the smaller of his two heaters is rated above that. We had a mechanical thermostat on the "welder" plug and that failed in time, even though it was supposedly rated for the load. I'd be willing to do something like that again if it's rated for 25 or 30 amps, if not higher, but I don't know how my brother might feel on that. I'll likely be paying him a visit in the next couple days and then I can take better notes on the situation.

    This may be only an intellectual exercise in the end because none of these solutions are all that cheap and the heaters and air conditioners are getting "smarter" every day, which might render the whole exercise moot by the time we actually go shopping for a new AC unit for the shed. I'm guessing that he'd rather just get the "smarts" in the unit and/or maybe that Wallflower plug. The Wallflower isn't cheap but it's the lowest cost solution so far and it's got some nice features and can be used for other things, like it's intended use as an oven safety device.

    Thanks for the advice so far, it's been very helpful if only to give me some better ideas on what kind of keywords to search for when shopping. If there's something that can make his "dumb" heaters "smart" for a reasonable price then I'm guessing it would be something he'd buy if only as a temporary measure to get him through the coming winter.
  7. CX3CP

    CX3CP Ham Member QRZ Page

    OK, cheaper than those wifi modules do not think there is, but nevertheless, I give you another option even more economical, and with more capacity. 16 channels.
    you will not find anything the size of an AC plug that can handle the power a heater consumes. Therefore, you will definitely need relays for such loads.

    Following you will found some directions that I think will help you, if not now, may be in the future.

    And about the "BOSS matters", not much to say, I know what do you mean. but again, I also have an BOSS, and in the terms of technology and especially electric issues, definitely I am the boss in my house.... when she want, obviously :rolleyes:


  8. AC0GT

    AC0GT Ham Member QRZ Page

    That's totally overkill. He just wants the means to "preheat" the garage while picking up the kids so they have a warm place to play while supper is being made. What you propose has "some assembly required", to put it mildly. Setting aside any issues of passing inspection from the powers that be, this must still be something that isn't going to be a big time sink. Changing out an outlet for that Wallflower device is a few minutes of work. Putting in an electrical box for a Wemo switch is maybe a couple hours. Hooking up a relay control center with an embedded web server, connecting relays, and wiring them up to the outlets, would take an entire weekend.

    Huh? The Wallflower smart plug does that. It handles 50 amp 240 volt loads and is not all that big. I think that the advert on the website understated the size a bit but it looks like it's fairly small. Most importantly it's "plug and play" simple to install.

    Yes, that may come in handy. Not in this case though.
  9. AC0GT

    AC0GT Ham Member QRZ Page

    I now recall why the lack of a neutral wire for the one 240 volt outlet concerned my brother so much. The plan was to have that outlet switched remotely by some means to operate heat or cooling. With a neutral wire there it would be trivial to have an adapter to plug in a 120 volt load, such as his current air conditioner, and still be able to unplug that to plug in a 240 volt load, such as his heater. The matter of managing the switching based on if it controls a heater or cooler is just software. That outlet is also a circuit separate from the circuits used for the electronics and lights in the garage. As it is now the air conditioner is on a circuit with a bunch of other stuff and getting it on it's own circuit is simply preferable for a number of reasons.

    Now, there is in fact a neutral wire in that box but it's for a different circuit. If I thought I could justify it being safe to tap into that I would. I am instead considering two different options.

    Option 1:
    Find a 240 volt to 120 volt transformer of sufficient capacity and with the proper connections to be a "plug-n-play" solution. There's a few transformers that should work, including this one:
    Which would need an adapter to plug in like this one:

    This option might register as a "hack" and not pass inspection. It is though relatively low cost and not require any rewiring, even so much as a switching out of the outlet.

    Option 2:
    This option requires some rewiring but nothing major. As I recall the outlet has a dedicated ground wire and I'm certain the wiring is in metal conduit, making the ground wire redundant. This means I can re-purpose the ground wire as a neutral for installing a four prong outlet. To do this I'd have to find which wire it was in the breaker box and mark it as a neutral with white tape. Then to make sure this install is safe I have options.

    Option 2A:
    With a self grounding outlet in the metal box the outlet is grounded with a path through the box and conduit to the main breaker box. This should be sufficient, especially since the other circuits that share the conduit have their own ground wire. Even without a self grounding outlet I can run a wire from the ground screw on the outlet to a ground screw on the box.

    Option 2B:
    I know that with ungrounded 120 volt circuits it is permissible to use a GFCI breaker on the circuit with a grounded outlet, so this option is to use a GFCI breaker on the circuit to compensate for the lack of a ground wire. I don't know if this applies with 240 volt circuits, and I doubt it does so I am leaning towards...

    Option 2C:
    Do both A and B. Have a self grounding outlet and a GFCI breaker. If anyone happens to look into this there will be both grounding for the outlet through the metal conduit and GFCI protection. The use of a self grounding outlet effectively costs nothing, as the non-self-grounding outlets cost the same. However, a 20 amp double pole breaker is not cheap.

    This is the outlet I have in mind:

    This adapter would be for the air conditioner:

    This adapter would be for the heater:

    To control the outlet would be something like this:

    I found out why all these baseboard heater controllers are rated for 16 amps. Electrical code requires something considered a constant load to consume no more than 80% of the breaker rating. A resistance heater is considered a constant load. For a 20 amp circuit at 80% means the load can't be more than 16 amps. It just so happens that the heater my brother has now on this circuit is a 3800 watt unit, which draws less than 16 amps.

    The options I gave here might not be any cheaper than what I thought up before but it's all relatively plug-n-play, has a real thermostat, and is controlled remotely. The down side is that it might mean putting an air conditioner on a circuit controlled by a baseboard heater thermostat. The air conditioner will have it's own thermostat so as long as the WiFi thermostat can be put in a state to not interfere then it should work. Either option also allows for future change to a bigger air conditioner without another rewire.
  10. AL4Y

    AL4Y Ham Member QRZ Page

    I’d be inclined to intercept the 240v circuits and install an appropriately rated double pole relay or two pole contactor between the circuit breaker and the outlet. Then wire the coil to a 5-15p and plug it into the Wemo remote control outlet that you already have. Functional Devices Inc. makes a series of products called relay-in-a-box that can be close nippled to the thing you are trying to control, which makes for a fairly clean installation. The RIB01P30-S may work for you.
    WR2E likes this.

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