US 220V Wifi Switch
February 13, 2017 5:44 AM   Subscribe

Does anyone make a >>>US<<< 220V wifi switch/receptacle?

I have have an odd-shaped, but huge warehouse space that is ar conditioned by 3 reliable, box, through-the-wall, 25,000 BTU units. Each unit runs on its own dedicated 2 pole 20 amp circuit. Each is plugged into a heavy-duty 20 amp, 227 volt receptacle in the / . \ configuration.

I'd like to be able to turn the units on and off remotely, and have been trying to find a wifi switch to put between the plug and the receptacle, but everything I keep finding is based on European/UK configuration.

Is there any US 220v wifi switch that will work?
Or is there a solution for using the EU/UK devices in this situation?

Thanks in advance!
posted by sandra_s to Technology (9 answers total)
Try this:
posted by bgroff at 6:24 AM on February 13, 2017

Here is bgroff's link.

If you don't find a US plug version, you could use the European device and make adapter cables.

You described the US plug as "/ . \". Which of these NEMA plugs matches it? NEMA 10-30? No matter which way you go, you'll need to know that.
posted by intermod at 6:26 AM on February 13, 2017

You need something like the hard-wired, expensive product above. Do not put anything in between a 25,000 BTU appliance cord and the wall plug.
posted by rockindata at 6:30 AM on February 13, 2017

Do not put anything in between a 25,000 BTU appliance cord and the wall plug.

Yeah, just to be clear: an AC unit that can cool 25,000 BTUs/hour probably consumes something like 600–700 watts on average, and so is probably drawing 3–4 amperes of current while it's running. Because of the nature of electrical motors, the electrical current that is drawn right as the device starts up is probably higher than that; the owner's manual for your AC units might have information about their "peak current draw". Be sure that whatever product you buy is rated to handle the peak current draw; I suspect that many simple "plug-in" wifi switches are not rated for the large currents that are drawn by AC units.
posted by Johnny Assay at 7:43 AM on February 13, 2017

And to provide a more physical sense of why this is important, the inrush current when you start these things up can be so high that something you think of as a "switch" can instead become an instantaneous tack welder, and either (good scenario) vaporize or oxidize its own contacts so it never works again or (bad scenario) weld those contacts together so it's impossible to turn off. There is certainly automation and control switching equipment rated to handle this (and more!) but it's not going to be cheap -- it will be expensive enough that the cost of an electrician to replace the plug or hard wire it will be a fraction of the budget.
posted by range at 8:20 AM on February 13, 2017

You'll need a relay . More here. And some other components.

Really, this is the sort of thing you should hire an HVAC electrician for. You can certainly homebrew one, but I've got a degree in Electrical Engineering and I'd hire this out. It's not super expensive - as you can see parts are cheap, and its only a few hours labor. You're paying for expertise, and that benefit of that expertise is not burning the place down.
posted by Pogo_Fuzzybutt at 8:30 AM on February 13, 2017 [4 favorites]

How are the AC units themselves currently controlled ? I'm guessing manually because they are box-through-the-wall, rather than as part of some building automation setup.

A building automation solution is probably the right answer for the "how do I remotely controll my AC unit" problem (and then you could integrate the warehouse lights, access/security/cameras etc as well). It probably isn't the fastest/cheapest, but would be the right approach.
posted by k5.user at 9:12 AM on February 13, 2017

The relays above would work (and that's what you're designed for), but then you do have to roll your own Arduino or whatnot-based controls system, etc, etc.

Instead, I'd suggest that you use a home automation system, and not one that uses 802.11 wifi.

I use Z-wave - it's a mesh-networked home automation protocol shared between companies, not a proprietary system, so you're not locked into one company. Depending on your need for customization, you could get a Samsung SmartThings base station, or an ISY994 base station, etc

And then, you can use Z-wave enabled relays like this - it looks like it can handle 9600 watts, so at 240V, that's 40A, and it expects 8~10awg wires as input.

There's a lot of solutions that work with Z-wave - thermostats, lighting, garage door, fire alarms, wall outlets, etc. Most powered devices are also repeaters (like the one I linked), so they also extend the mesh network beyond the base station.

The benefit of this is that the electrician costs are low - you'd just need someone who can, given a 40A 3-phase plug, wire the relay in-line and perhaps mount it nicely inside a NEMA-rated enclosure.
posted by suedehead at 1:12 PM on February 13, 2017 [1 favorite]

One other idea:

If you're handy with electronics and soldering, then you could assemble this 240V Powerswitch Tail kit, which is essentially a relay in a safer plastic enclosure.

You could then have a standard 110V DC adapter wired directly to the Powerswitch Tail, so that when the DC adapter is plugged in, the relay is on.

Then you can find any 110V wifi switch you want to use, and plug the DC adapter into the wifi switch.

Wifi switch turns DC adapter on off -> DC adapter turns Powerswitch Tail on/off -> Powerswitch taill turns HVAC unit on/off.
posted by suedehead at 1:19 PM on February 13, 2017

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