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High current/power switching

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High current/power switching
« on: March 19, 2017, 06:04:57 am »
Does anyone have any experience switching things like water tank (immersion) heaters where there is a high current requirement? My water heater switch is at the top of the house (and I'm not as sprightly as I once was).

The TP-Link HS100, for example, is rated at 2.99 kW (here in the UK). But my tank heater is rated at 3kW so that's too close for comfort.

Re: High current/power switching
« Reply #1 on: March 19, 2017, 12:45:34 pm »
It may just have to do, though.  Here in US, outlets are rated in amps, and 15 amps is standard for most room outlets or 20 amps for others.  Anyway, the HS 100 is rated here for 15 amps.

Re: High current/power switching
« Reply #2 on: March 20, 2017, 04:31:06 am »
Here in US, outlets are rated in amps, and 15 amps is standard for most room outlets or 20 amps for others.  Anyway, the HS 100 is rated here for 15 amps.
True, but that's at 110 V, so the maximum power rating for the HS100 is 1.8KW in the US.

Re: High current/power switching
« Reply #3 on: March 20, 2017, 11:00:25 pm »
OK, bur US model does not show a power rating, although it does say the maximum load is 15A. (using 100-120 AC)   Does your model say that?  DC and AC power is a relationship between voltage and Amps (current).  DC formula is easy, P = V x A , but AC formula is different. so you may want to look up formula.  If the device you are powering draws less than 15A, you may be fine using the plug.

Re: High current/power switching
« Reply #4 on: March 21, 2017, 04:16:09 am »
Yes, AC power is trickier to calculate. Those figures for UK and US power ratings are from TP-Link's web sites.

I've done a bit more research and most people use a relay. The solution that's posted most often is to use a Wemo Maker and a 5V DC / 240V AC relay. The Wemo Maker is the hobbyist Wemo; the kind of thing that people who play with Arduinos would use. Trouble is, a regular Wemo plug is expensive enough; but a Wemo Maker is about double that price!

If I used a regular Wemo or TP-Link, I'd have to find a 240V AC / 240V AC relay. And that seems more exotic and difficult source correctly.