The buyer’s guide to electric-car charging stations | 220v Contactor Relay

First rule of LO-TO: if you didn’t LO-TO it yourself it’s not! I will never EVER trust anyone to do a LOTO for me. If I’m to stick my hands into something dangerous the key to that lock on the switch is going to be in MY pocket!

I think that one of the statements that stuck with me the most while doing LV operations training was from a doctor who said “If you are admitted to my hospital with electrical burns then I will do my utmost to make sure that your family get here before you die”

Online reviews are useful when you’re on the hunt for a trustworthy electrician. If the person with the lowest quote also has the worst ratings, it’s worth shelling out a bit more. If that cheaper electrician messes up, you’ll just need to call me (and my higher price) and pay more overall.

I worked in telephony for many years, and the ring voltage can be as high as 180 bolts at various frequencies, but, rather low current. In really old telco systems it may also be a square wave.

In college, I was playing with our nitrogen laser which had a huge exposed Blumlein discharge capacitor. So large that a bottle with fluorescent die had been set on it. While the laser was running, I picked up the bottle, and received several 20-30kV discharges to my hand. The exit was my bare feed on concrete. I was able to count the hits afterward, because each one left a small burn mark on my hand. That hurt.

You do in fact need to be a licensed engineer/electrician to design stuff with mains voltage, or you need to have your work inspected and signed for by one. It’s not just a matter of good instruction – it’s illegal for the regular Joe to even repair mains powered circuits beyond swapping a frayed power cord.

The Sony A33 uses the image sensor itself when metering, and considers the overall image as 1,200 separate zones in performing metering calculations. Metering modes include Multi-segment, Center-weighted, and Spot, and the metering system can function from -2 EV to +17 EV (at ISO 100 equivalent with an F1.4 lens). An autoexposure lock button is provided, allowing metering to be locked from a specific portion of the subject, then the overall image reframed as desired. +/-2.0 EV of exposure compensation is available, in 1/3 EV steps. The A33 also offers a three-frame exposure bracketing function, which allows a step size of either 1/3 or 2/3 EV between subsequent frames. Shutter speeds from 1/4,000 to 30 seconds are available, as well as a bulb position that holds the shutter open for as long as the shutter release is pressed. Flash X-sync is at 1/160 second. White balance options include auto, six presets (Daylight, Shade, Cloudy, Incandescent, Fluorescent, and Flash), plus both custom and direct color temperature (2,500 to 9,900K) options. The six presets allow +/- 3 step adjustment, and there’s also a color filter setting that provides +/-9 steps of magenta / green compensation.

This seems to me that your experiment failed due to thermal failure cased by insufficient cooling and not the part itself..You stated yourself that the part failed due to thermal expansion (insufficient cooling). But it’s still a valid experiment with valid results. And you show that it’s up to the designer (or designers) to design the entire product, which includes sufficient cooling. This is one area where home designs fail – a lot.

Five vs Ten amps is a big difference in heating in the power factor correction circuit of his power supply. If you find a data sheet for similar power supplies, they are always 1-3% more efficient on 220Vac and run cooler because of it.

I have pulled this hack in a pinch with specific pieces of test equipment, etc. (usually large power supplies) in non-residential settings but instead of having a snazzy box I would use one extension cord and my trusty Fluke and sort it out. In that application, the circuits were almost always dedicated (or near-dedicated), but in a residential setting, there are still many circuits that are rarely loaded much if at all, and I see this as working perfectly fine for those times.

3-phase installations like industrial facilities and some apartments are fed with 208V 3-phase, which provide three phases of 120V to neutral, or 208V phase-to-phase.

”Just like with laptops and mobile phones, sophisticated new features sometimes require new hardware,” Sonos said in its blog post today. “The computing platforms and software architecture in some of the older Sonos players simply don’t have the horsepower to support AirPlay 2. But by taking advantage of newer Sonos hardware, we’re able to make AirPlay 2 content available throughout the house on speakers old and new.”