Tom Baker is turning his long-lost Doctor Who movie script into a novel | 25 Amp Circuit Breaker

And use a power circuit with a differential circuit breaker so if you touch live wire it will disconnect.

Yes you can use those high voltage safely, BUT your typical DIY people don’t even bother to read or understand datasheets. These people need the proper training, but aren’t likely to be bother to go beyond the typical monkey see monkey do watching youtube and think they know it all. I have seen enough of bad layouts of the average projects that doesn’t even understand that the creepage space between the primary and secondary side of an optoisolator aren’t meant to be for routing!

The control buttons are for the most part intelligently arranged and readily accessible, but the small space available for them on the right side of the body does mean that you need to hold the camera in your left hand to be able to access them properly: They’re really too close to the right side of the camera to keep your fingers wrapped around the grip and operate the buttons with any degree of comfort. On the angled top/back panel, the EV adjust button is perfectly located, right under your thumb, with the AE lock and movie recording buttons on either side of it. The movie button does require a deliberate reach to get to, but is nonetheless easy to identify by feel when you’re looking through the viewfinder; just slide your thumb over until it hits the viewfinder housing, and you’ll be right on top of the movie button.

Indeed, I did a HV Course at a functioning power station where once you had isolated an 11kV switchboard you had to grab hold of the bus bars to show the other workers it was safe to carry out their work.

I to have worked with high voltage systems. My point was that it needs to be treated with a bit of respect or it WILL kill you even if not immediately. My friend was an electrician of many years. And sure, I hear lots of stories of how people get away with this and that, but that is just that they gotten away with it so far. They could be dead tomorrow.

And even today people give the advice of plugging a computer in the wall and grabbing the metal case as you’re working inside it. Bad idea – if the PSU has failed, you may very well have live voltages in the boards.

Current starts derating at about 82C (see page 12). But look at the size and configuration of the heat sink required for a 25A SSR, it is 100mmx100mm with lots of fins (see page 13). That will be with lots of free air, preferably mounted so the fins are vertical or with some forced air flow.

However there is a snag. In recent years there has been a flood of cheaper instruments arriving on the market, and some of the manufacturers of these devices have been found to put IEC 61010 ratings fraudulently on items which do not in any way meet those standards. We have covered tales of dodgy cheap multimeters and test failures more than once here at Hackaday, unfortunately this is a widespread problem. So please bear this in mind when buying a multimeter or other instrument for use with mains voltages: the cheapest may not be good enough. We have all used £5/$10 bargain meters with our low-voltage analogue or microcontroller work because a flashing LED on a breadboard is hardly hazardous, however for higher voltages those IEC class markings have to come with a believable provenance. Buy the most expensive instrument you can afford from a decent and reputable manufacturer, it’ll keep you safer and you’ll get a top-quality meter that will last you a lifetime.

Electric blankets have lots of testing to ensure they’re safely insulated from the user. They also don’t get nearly as hot. They also use too much power to economically run from a low voltage PSU.

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.

There are only two conductors run from the substation to a normal one phase installation. Those are live and neutral. Though the neutral is bonded to ground at the substation through the resistor and is also connected to earth at any and all points on the cable where any work is done it is still neutral. At the house the neutral and ground become separate conductors. The neutral is treated as a live wire when working on the system, as far as I know all utilities treat neutral as another phase for safety reasons.

You likely encountered a shared neutral between more than one circuit. You have to switch off the breakers for all the circuits that share the neutral.