*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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Specific Questions Regarding Use of Regulated Switching Supplies

For a project I am working on, I have 3 regulated switching supplies, 5v 5a, 12v 5a, 24v 2a. They are the standard, passively-cooled type which look like this My question: Can I stack these/have them ...
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2answers
66 views

Implementing Safety Shut-Off Relay In Project

I am working on a project which I have poured lots of cash into that involves water, pressure and electronics in very close proximity of each other... Lately, I have been considering adding some ...
2
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2answers
210 views

Why would you use a non-contact voltage detector if you have a multimeter?

I was reading this Fluke multimeter safety manual and I came across this sentence: ...
2
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1answer
41 views

Adding a resistive path between live conductors and earth - safety issues

(Note: I am in the UK so the terms 'line' and 'neutral' refer to the two live mains conductors) I am trying to establish a list of safety issues which I should be aware of if I decide to introduce a ...
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1answer
74 views

Intrinsically safe circuits

Is there a power threshold below which a circuit is considered to be intrinsically safe? For example, if one were to power a tiny Arduino circuit at 5vdc / 30mA = .15W could such a device be ...
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5answers
635 views

Can a charged 120v high voltage capacitor really kill you? [duplicate]

recently I have been hacking few psu and have to deal with some high voltage caps. It sort of scared me, but thinking about it, what is the chance of it really killing me. Is it safe to touch one ...
2
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1answer
76 views

is it safe to have hot wire connected to ground (metal case, shield) via a capacitor?

I have opened a psu, and I saw a small capacitor is connected between one of the ac inputs and to the ground/shield. We don't have ground in our ac outlet, so a hot 110v ac line could be connected to ...
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1answer
37 views

Do I need any special equipment to make my circuit run off power from a phone/laptop charger?

Is it safe for one to replace a 5v battery source with a phone charger without installing any other components to prevent power surges or injury to any people in contact with the device? Also, is it ...
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0answers
32 views

Charger failure safety measures

Suppose I use a charger to power a circuit and suddenly a component inside fails and the 220 volts can easily reach my project,flowing trough the now broken charger.What can I put between the charger ...
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2answers
95 views

DIY Laser Tag, Safety and Modulation questions

So I'm trying to build a Laser Tag game for some friends, I was wondering a couple of things Safety - I'm using 5mW red lasers from Aliexpress. I have no datasheet for the lasers, so I was wondering ...
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1answer
72 views

What happens if there is a fault in the neutral wire between the grounding pole and the centre tap of the transformer?

I was reading through some SE questions/answers on residential power transmission and came up with two scenarios I'm unsure about: Assume that your house is wired properly (with no degradation), but ...
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2answers
52 views

Combining a benchtop power supplies

So I made an error when purchasing a power supply that was far below desired voltage (dc). The power supply I bought certainly produced enough current, however, and I am wondering if it is possible to ...
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2answers
89 views

Capacitor safety

After looking at some posts,I started wondering if using capacitors,especially electrolytic ones is as safe as I thought.After making sure that the you don't supply a bigger voltage than the rated one ...
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2answers
83 views

Can you protect yourself from Tazers by lining your clothes with aluminum foil?

It seems like you could protect yourself from a Tazer by having a conductive metal in your clothing that would complete a circuit between the two prongs with lower resistance than your skin. Since ...
2
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3answers
109 views

Phone travel charger for powering circuits dangers

I am thinking of using a phone travel charger to power a circuit.Ratings: input:110-240VAC(my outlet has 220volts) 50/60Hz 0,3A output:DC 5,2volts at 400mA The problem is that 220 V are of course ...
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5answers
5k views

Is it safe to connect an Arduino to the human body?

I want to create some project which uses an Arduino to collect and display ECG data. It uses two electrodes which are attached to the body (on the chest). The signal is then transmitted through ...
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1answer
65 views

Potential safety hazard? [closed]

Suppose one uses a poor 18650 (low quality and without a datasheet) to charge a phone and the phone tries to draw 3A-4A (2A @5V) from it. Would this be hazardous even with a protection circuit built ...
2
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0answers
52 views

Is there a good book on designing for electrical safety with AC mains power? [closed]

Is there a good book on how to design for electrical safety, particularly when using AC/mains power? I have look on Amazon without finding anything that seemed appropriate. This topic is largely ...
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0answers
40 views

Could a lipo/18650 overheat during discharge?

Suppose a cheapish lipo/18650 has a typical protection circuit in place, which, e.g., shuts off the battery when voltage gets too low, shuts off the battery when the current exceeds 4A, and prevents ...
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2answers
69 views

How to properly use ESD protection wristbands

I've looked at other articles on EE stack exchange about ESD precautions. I would like to use a wristband for precaution with microcontrollers. Where am I grounding my wristband to? Do I ground ...
0
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1answer
79 views

LED strip underwater

I am working on a project where a LED strip is placed at the bottom of a pool which will send patterns of light along the bottom of the pool. I have looked into some LED strips and found a 5V APA-102 ...
2
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2answers
37 views

Where can the detailed requirements for EU Low Voltage Directive compliance be found?

I'm designing an appliance that probably has to comply with the European Low Voltage Directive. I've been searching for a guide on how to design a product complying with this directive, but I haven't ...
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1answer
47 views

How does a fuse affect creepage reqirements?

I am designing a mains-powered device that has to comply with IEC 60079-15 (Non-incedive industrial eqipment). Creepage distances in this standard are inherited from IEC 60664, pollution degree 3. For ...
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2answers
62 views

Safety/efficiency of a makeshift aluminium can heatsink?

I had recently received a 9v 1A DC wall-wart off eBay, and needed to open it to swap the polarity of the jack to center negative. As I had the case open, my finger bumped against the metal part of the ...
4
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2answers
487 views

Hazards of puncturing lithium-ion batteries?

I was doing some electronics repairs, and accidentally punctured a small (mobile phone capacity) lithium-ion cell battery with a metal spudger. At first, I hadn't realised I punctured the batteries - ...
2
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2answers
117 views

Does any company manufacture American AC power plugs with insulated pins?

In Australia and some other places, good-quality AC power plugs have "insulated pins". This means that there is a short length of insulation covering the base of the pins. Darren Yates writes that ...
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1answer
64 views

Automotive power supply - considerations for selecting fuse

A power supply circuit for a device that runs off the 12V battery of a car, is shown below. simulate this circuit – Schematic created using CircuitLab LM7805 is used to generate a 5V ...
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2answers
703 views

Why are caps configured this way in EMC filters?

Every EMC filter I've seen has capacitors between the AC lines and earth, configured like this: simulate this circuit – Schematic created using CircuitLab Why are the caps not configured ...
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1answer
54 views

What is a safe level of electromagnetic radiation measured in terms of received signal strength indicator (RSSI) e.g. -26 dBm?

We know that the laws of our countries set the regulatory limits of EM radiated power based on the EIRP transmit power of the antennas of devices. However, the received incident power is more ...
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0answers
54 views

0.8mm PCB for a PSU circuit

I am working on a PSU that converts 230 VAC to 12Vdc (0.1 A). The board has the necessary clearance and creepage distances. Would it cause any safety issue (IEC60950) if the 0.8 mm (or 1.2 mm) thick ...
4
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5answers
224 views

A “fuse” that blows upon liquid exposure instead of overcurrent?

I have a board that is mounted inside a waterproof housing, but occasionally the housings develop leaks and expose the internal circuits to water. This can cause unpredictable failures as the ...
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1answer
62 views

USB shield shorts battery… protect the PC?

I'm making a retro-fit device (so I have plenty of parameters that aren't in my control) where we're adding USB connectivity to the device for use with a PC. The device is battery powered, and the ...
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2answers
122 views

When does a human body get shocked by electricity [closed]

Today I touched the live phase of the electrical line of my house wearing rubber shoes. However, I still got an electric shock As I wore rubber shoes it seems to me that I shouldn't be get shocked. ...
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1answer
44 views

Is matching an infinite switch rating to a heating element required? [closed]

I want to use a Robertshaw universal infinite switch rated at 15 Amps to power a heating element to boil water in a stainless steel tub. The voltage is 240 VAC. A heating element greater than 3600W ...
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2answers
49 views

Creating small heater

I need to make a small heater. I was looking at this project: http://www.makeuseof.com/tag/make-your-own-temperature-controller-with-an-arduino/ but I need to design the heating element. I was ...
3
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1answer
49 views

Can a FELV circuit be connected to a SELV circuit?

This might be a very very simple question, but I'm unsure how to interpret the rules. I have a circuit which switches 230V using relays. The circuit is a motor controller for a motor control box ...
3
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1answer
88 views

Is a device with high voltage and low current safer than a device with low voltage but high current should you accidently bump into the +/- pins?

For example, my lead acid car battery is rated at 12 V/700 A, whereas my switch mode power supply has 250 V/6.3 A. If I were to accidentally bump into the +/- pins of either battery (forming a full ...
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1answer
62 views

Considerations when repairing dimmer switch

I originally asked this question on DIY StackExchange. So far no answers and a suggestion to try on Electronnics, so here goes: I have an IKEA lamp with dimmer switch which took a knock and ...
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5answers
6k views

Is this true: “At over 700 Hz, current simply flows over your body”?

I have heard this in a movie clip. I was just curious to know, is this really true? Because the one thing that I do know, is that at a high voltage, the current decreases, so that it doesn't harm a ...
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0answers
32 views

Portable Power Unit for 18V Power Input Device

Background I am experimenting with music mixing. I want to be able to record my music while "on the move", that is, not in the house, but in my car, so I can drive somewhere quiet and enjoy my ...
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1answer
63 views

Fuse rating and safety

Under what conditions would a faster, higher rupture capacity, higher voltage-rated fuse be less safe than the equivalently current-rated fuse which was slower, lower rupture capacity or lower ...
0
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3answers
316 views

Function generator as a DC power supply

I'm wanting to start my own lab at home so that I can learn things faster than uni teaches (we're not allowed into labs unless we're in our own lab). A friend said that I'd be better off getting a ...
10
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3answers
2k views

Mechanically damaged capacitor leaked liquid - is it toxic?

I have mechanically damaged a capacitor on an old motherboard and it made a PFFFT sound like some gas went out of it and then some liquid leaked. What is that? Is it toxic? I hope that it was not ...
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4answers
157 views

soldering protective gloves

Do you use any protective gloves while soldering? It has happened to me a lot that hot solderer touches my fingers. I am not sure if protective gloves would reduce freedom of my fingers for their ...
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2answers
90 views

what safety glasses

As far as I know soldering glasses are for eye protection against lead fume. As a personal experience I have observed some parts of lead with tiny explosion due to heat come out of lead with a smoke ...
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0answers
66 views

Safety/Quality issues by modding PC PSU to be floating.

Since I don't have enough money at the moment to purchase a good bench power supply, I want to 'mod' a PSU. In the first instance not by opening the PSU, but just by making an adapter that also puts a ...
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2answers
73 views

Computer Power Supply Testing Safety

I have a 750 watt ATX power supply that I will be testing with a multimeter to make sure the right voltages are present. How can I make sure that I do this safely? Is there anything that's threatening ...
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1answer
94 views

What is the current path when you touch the 230 V outlet?

The outlet's potential is 230 V, the earth's potential is 0 V. The person touching the outlet will get shocked, but why? What is the path that completes this circuit so current will flow?
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3answers
291 views

Is it safe to treat a system downstream of a reverse-biased diode as de-energized?

Suppose I have a 480 VAC line, feeding a rectifier and filter caps. Obviously this is not something to be trifled with while live. Now, suppose there are blocking diodes coming off the DC bus, as ...
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1answer
295 views

Transformerless power Supply - 24VDC, 120V AC and 230V AC

I want to know if it is possible to design a power supply for a circuit that can operate from DC and AC using the same input terminals. Thus, the output should be xxV DC (5-24 or whatever is decided ...