New Google Classroom update makes it harder to cheat on quizzes | 19mm Momentary Push Button

For transient rise times of 0.1 to 0.2 μs, twice the unit value of surge capability is required on stator windings. When rise times reach 1.2 μs or greater, 4.5 times the unit value is stipulated. In the case of external transients such as lightning, this would equate to a surge voltage capability of 918 VPEAK for a 230-V motor (full load current = 12 A) on a 250-V high-line condition. (Lightning surges can exceed these values, so stator windings would also need a suppression element for protection.)

And in my own experience, I have seen switch mode power supplies designed for 400 volts DC (280 volt AC), taking clearance for such into consideration throughout the whole design.

My own maxim is that just because something can be – and perhaps often is – done poorly or hazardously does not at all preclude any possibility that it can be done properly and safely.

Pools have come a long way. It used to be you had a pump and if you were lucky it had a mechanical timer switch on it. That was it. Now you have digital controllers and spa jets and heaters. You can even get them that connect to your home automation system. If your pool isn’t new enough to do that already, you can get a range of add-on accessories. For a price. [Rob] paid $500 to get a remote for his pool. It wasn’t even WiFi, just a simple RF remote. In 3 years, the transmitter had burned out ($300 to replace) and he decided he had enough. For $20, [Rob] added MQTT control and monitoring to his pool using an ESP8266. You can see the video description of the project below.

I was mainly thinking about the diff between high vs. low RMS AC voltage but the discussion of AC vs DC has been interesting as well.

Is it possible, that the discreet triplers (vs. diode split transformer) were in the time of BW-TV? They had lower power. Or the guy tested the AC before the tripler, I think that would make a great difference. Although I also would not do this intentionally. There would also be a nice arc to a grounded screw driver, if you want to test the HT – without any current path through myself, what I really prefer. The electrician, whom you mention, did he really die while testing for voltage with his hand, or was his accident unrelated to this?

Comparable relay product datasheets from Omron suggest that without appropriate heatsinking, the current limit should be in the range of 4A to 7A.

A properly wired, properly functioning dimmer switch can get hot to the touch. I’ve found that a 65-degree temperature rise is normal for a maxed-out dimmer. If the ambient temperature is 71 degrees and a dimmer switch is at 136 degrees, I’d be concerned, but I wouldn’t report the temperature as a problem. I would, however, take an extra minute or two to figure out how many watts the dimmer is rated for. I’d then make sure there wasn’t too much being controlled by the dimmer.

I get called in all the time for problems with space heaters. If you leave the house while the heater is running, the connection could get loose and burn up the plug, which could start a fire. Give your space heater the space it needs, and turn it off when you aren’t using it. Learn more about how to use a space heater safely.

It’s neither a sports car nor a hot hatch — it’s just a tall hatchback masquerading as a crossover. It handles a bit better than most commuter appliances, due to the 258 pound battery mounted low in the chassis. Imagine strapping me, Keanu-under-the-bus-in-Speed style, to the undercarriage of a car. That would let the car hug the road a bit more (and seriously wound your favorite bearded auto writer, so let’s keep this hypothetical).

He welded the base of the magnets to the plate that is hold directly to the crane with a hook. Look again.

All this stuff makes me think it might be time to get a Faraday cage installed around my heart. Or maybe a big shunt from shoulder to shoulder.