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Questions tagged [safety]

*Your* health and safety while working on electrical devices, and designing devices that will not shock, set fire to, or otherwise harm the user of the device.

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3answers
2k views

Issues with resistor heating, for an LED?

I am direly confused on this. I've used 220 Ohm resistors in the past for all of my LEDs (at least that I can remember), however nothing on my arduino+breadboard with a few leds on the 5V breadboard ...
7
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1answer
151 views

How should unidentifiable breakers and fuses be represented in arc flash studies?

When analyzing arc flash hazards in industrial power systems, I have encountered situations in which visual inspection reveals the manufacturer and the trip rating only. The breaker or fuse model ...
3
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3answers
959 views

Static dissipative ESD footware

Are shoes like this used in professional labs or is this just a gimmick? http://www.esdshoe.com/products/Lightweight-Classic-Mid-High-ESD-Composite--Basketball-Shoe-%252d-Men%27s.html
19
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13answers
4k views

Path for a child to learn electrical engineering

What are some paths for a child (7-year-old) to learn electrical engineering (in a safe way)? I do not want to saturate (or frighten away) the child with lots of concepts, I want that my son learn ...
2
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1answer
2k views

Safe operating area for different types of battery chemistry?

I'm trying to find the safe operating area for various types of batteries; in particular I need minimum and maximum termination voltages, although information on temperature / power / current is also ...
2
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3answers
2k views

Are solenoids/inductors dangerous to have exposed?

An inductor doubtfully will be in a position to be of harm, however a solenoid with 1A+ running through it (and of course a lot of it stored in the magnetic field) can certainly harm the circuit, if ...
7
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3answers
3k views

Decomposing Kinect Laser Projector - Is it really safe?

I am looking at Kinect Laser and couple of things that are not clear, so I thought I bring up here. First the known facts: - Kinect has a laser projector that works at 840nm - Output power of the ...
5
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2answers
2k views

Chassis + Ground Safety

Why is it safer for ground to be connected to the chassis for an electronic system? For example, the ground on the mains supply of an AC motor in a box fan is connected to the outer chassis of the ...
4
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3answers
516 views

Is there a wiring design that would protect a person in bath from electrocution when a powered appliance is dropped?

Hairdryer falling into bath is a Hollywood cliche already. Jokes aside, is there a wiring design that would protect a person in this case? Overcurrent protection will trip too late, residual current ...
3
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2answers
884 views

How to properly isolate multiple power supplies

Say you have a single 110V AC supply and need to use it for a number of devices, each requiring very different characterists. For me personally these are: a direct use of the 110V AC supply for a ...
7
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3answers
2k views

Why is power supply from electrical utility referenced to earth?

In response to the question Basic Training for working with 120V AC zebonaut had replied that "A regular wall outlet is referenced to earth" and this provides the close loop for the circuit to ...
7
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8answers
2k views

Basic Training for working with 120V AC

I'm planning to build a digitally-controlled light dimmer circuit. I'm not trained in electrical engineering, and I don't want to do something that an electrician would immediately recognize as ...
1
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1answer
261 views

relationship between temperture, current, thickness, and material

I used lan cable for light LED up on my bread board power source is PC's power supply. without any resistor, the lan cable melt! I reallize I have to keep OHM's law in my mind and use proper ...
3
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2answers
245 views

cable jacket melts

I am new to hardware. My breadboard just arrived and I am trying to light up my LED. I used computer power supply for power (red wire for + black for -) and used strands of LAN cable for connect LED ...
3
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3answers
3k views

Any problems with “floating” an oscilloscope?

I have a Chinese scope with a two-pin power cord and a plastic body, and measure megaohms between its ground terminals and the actual earth, so I believe it has an internal isolation transformer (I ...
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2answers
356 views

Safe to open old sony remote?

I have an old sony universal remote, the rm-v15. I opened it to get to the pcb, and a strange nasty smell came out of it. Is there anything I should be worried about? Any hazards used in old remotes?
12
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3answers
6k views

Extra negative battery cable when charging outside car?

If you go to: http://www.battery-chargers.com/charging_instructions.htm ...Under "Operating Instructions" part "B: Charging battery outside of vehicle", it says you have to attach an extra jumper ...
2
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3answers
2k views

Switching 120V AC with Digital Logic on Isolated Power Supply

Context: A digital phase-controlled light dimmer system. 120V AC mains I use an isolating transformer (and rectifying circuit) to generate +12V and +5V DC rails. I want to use reverse phase control (...
16
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9answers
5k views

Safety of making PCBs

I've been making a few hobbyist PCBs at home and note that the photoresist developer and ferric chloride etch solutions are both pretty nasty chemicals that come with all kinds of warnings. So I've ...