This robot uses AI to find Waldo, thereby ruining Where’s Waldo | Lrd12 Overload Relay

This! I just want to add: >3. Verify that the system is really dead. Use an appropriate tool. Test the tool, test if the system is dead, retest the tool. It should be broken or may have broke while testing. >Use nonflammable clothes. Yes! Synthetic materials melts, sticks to your skin and burns – you don’t want this! >Use electrically protective gloves. and check them before use! Do not work alone and if the second person has no clues about electricity instruct him: -What NOT to touch. -CUT THE CURRENT before trying to help somebody that has been electrocuted. -Where the main breaker is and how to operate it. Have a fire extinguisher and a fire blanket (if you catch fire) handy.

A clean filter is vital to a well-functioning air conditioner. During the summer it is good to check your filters once a month. If you have pets, leave windows and doors open, or have allergies, you may need to change your filter more often.

I bought an optically isolated unit that is a “Solid State Relay.” ( SSR)The insides are some kind of zero crossing SCR/TRIAC I’m sure but the key is that the input is a logic signal at a few ma anywhere between 4-30 VDC. This unit is rated to 250VAC at 50 amps. I use it with a foot switch and DC wall wart to turn my welder on and off. It DOES require a beefy heat sink for that kind of power but it hasn’t even broken a sweat (my welder uses around 40 amps give or take.) I would strongly recommend adapting this circuit to take advantage of one of the many available SSR’s out there and let a professionally made and UL certified device handle the mains side. You just drive one of these with the GPIO side here. Of course you can use a much smaller unit for doing the typical 15 Amp light circuits. I actually used such a unit controlled by an Arduino to switch a hot plate (1000 watts) on and off for my flow soldering rig where the Arduino automates the solder temperature profile. I think it is best to marry our “hacks” to these commercial components that have proven performance/certification for our mains. My two cents ‘

There is a reason SSRs come with four bolt holes and a wide, flat aluminum base. And a reason manufacturers use these large heat sinks on them, and don’t forget a thin film of thermal paste:

Zaprodk bitches about the absence of a fuse — which is clearly explained to be located on a separate power entry board.

I often say this, and I will say it again: just because a thing is often done poorly, foolishly or dangerously does not in and of itself preclude it from being done properly.

All of this, if you suppose that you are taking a full hand of cable. Got shocked a few times with AC (and DC as well) and since I was just thouching, not handling, I had no trouble to get away with it (just swearing A LOT and throwing my screwdriver through the room).

A 40G HWH uses 3000W elements. Constant draw is 12.5A@240V and requires a 20A breaker (max draw / 80% safety margin = 15.6A so round up to 20A). 60G uses 4500W or 18.75A@240V and requires a 30A breaker (23.4A @ 80% safety margin so round up).

Would that have ever been considered good wiring practice, or is it just the sort of short-cut that would have been done at some point?

1. Metal-oxide varistors (MOVs) are available in a variety of form factors and sizes for a broad range of applications. The radial leaded disc type is the most common version.

I came here to post those two points! The corollaries to 1) are that should something go wrong, you have a chance if there is someone else there who knows CPR. I like mandatory CPR training for lab workers because of this. AEDs are good too. Rules against playing with things that can shock you while working alone are also good, but much harder to follow–I’ve spent decades working alone in research labs. CPR fails way more often than not, but electrical shocks are an important exception to that rule. And you almost got the extra credit for correctly spelling arrhythmia.

So far we have discussed your bench and associated equipment. We are not however quite done though, because there is one final component in keeping your bench safe: you. If you have a piece of equipment in front of you and you are about to open it up, the most significant part of your safety routine doesn’t lie with your equipment, but in how you approach it.