*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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5
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1answer
36 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 ...
-2
votes
0answers
19 views

Powering Qualtek 320-5

so I recently purchased the Qualtek 320-5 for a project and I have to admit that I have never used anything other than traditional benchtop power supplies at school that come with plugs in the back. ...
2
votes
2answers
49 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 ...
3
votes
2answers
146 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
votes
2answers
99 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 ...
1
vote
1answer
37 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 ...
15
votes
2answers
631 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 ...
-1
votes
1answer
42 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 ...
1
vote
0answers
53 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
votes
5answers
213 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 ...
0
votes
1answer
57 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 ...
-3
votes
2answers
88 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. ...
-1
votes
1answer
37 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 ...
0
votes
2answers
47 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
votes
1answer
43 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
votes
1answer
84 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 ...
1
vote
1answer
49 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 ...
17
votes
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 ...
0
votes
0answers
30 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 ...
1
vote
1answer
43 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
votes
3answers
135 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
votes
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 ...
0
votes
4answers
127 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 ...
1
vote
2answers
73 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 ...
1
vote
0answers
62 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 ...
1
vote
2answers
67 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 ...
0
votes
1answer
89 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?
9
votes
3answers
287 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 ...
0
votes
1answer
175 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 ...
10
votes
7answers
876 views

Mains Voltage on Strip Board

I need to prototype something quickly as a proof of concept. Is it safe to use mains (UK 230V) on stripboard? It will be going to a transformer so I can control some appliance. Or should I design a ...
0
votes
0answers
30 views

Fuse header for GPIO pins?

I have recently gained interest in electronics & tinker with Arduino & Raspberry Pi. But I made some big mistakes & ended up frying my board with mains AC supplied to the GPIO :( (yes, I ...
0
votes
1answer
62 views

How to wire a RCBO/GFCI correctly (in series with the upstream RCBO/GFCI)?

For one of my projects, I need to add a RCBO/GFCI for the protection of the users. I know that there is a RCBO somewhere up the chain, therefore I am facing a confusion: there is a non-zero resistance ...
5
votes
1answer
97 views

Electric shock from laptop due to capacitive coupling?

If a person touches an exposed wire (the wire has a ground-prong) on the 20V side of a power cable while barefoot, I heard that it is possible to receive a shock of higher than 20V due to capacitive ...
1
vote
2answers
213 views

By touching neutral why we do not get shock?

According to Benjamin Franklin, current flow from +ve to -ve terminal. But after Joseph Thomson's discovery it was conceived that although current flows from +ve to -ve electrons flow from -ve to +ve ...
6
votes
4answers
1k views

Which are the safety recommendations for soldering?

I was reading about tin alloys for electronics soldering and found it it has about 40% of lead in composition. Lead, everyone knows, it's very dangerous to breathe it due to being a heavy metal. Also, ...
1
vote
1answer
76 views

Transmit electrical signal across human body [closed]

Is it possible to transmit and receive an electrical signal SAFELY using the human body as a medium? For example, I would have a transmitter of some sorts in my left hand, and a receiver in my right. ...
1
vote
2answers
58 views

Getting UL certification for neon signs

I make neon lights and have been for 10years on my own and just recently found out that I could get in alot of trouble for not having my signs UL certification done. I want to make it right and want ...
1
vote
3answers
85 views

Using A Relay To Control A Lamp

I'm experimenting with capacitive sensors acting as switches and want to actually give my circuits some practicality. I've been researching how to use relays with microcontrollers (in my case, an ...
1
vote
3answers
41 views

Boost converter safety during debugging

When I was debugging my microcontroller-based boost SMPS I accidentally got 85V (instead of 15V as I intended) across the 1kΩ test load resistor. Does this spell a hazard for the one debugging the ...
0
votes
3answers
98 views

Why is this person shocked?

The voltage over the person is 250V. Why does he receive a shock? Doesn't the earth have a very big resistance so the current will be very small?
0
votes
2answers
51 views

Operate Arduino Nano using variable voltage

How safe/dangerous is it to operate an Arduino Nano 5V with a varying voltage source? I have a circuit that provides a duration of power with a starting voltage of 5.3V and an ending voltage of 4.5V. ...
0
votes
2answers
76 views

Is it necessary to have insulator sheets between PCBs and antistatic mats?

I am recommended to use some insulator or paper sheets when testing PCBs on antistatic mat connected to ground via antistatic wrist band. Is this correct way. Why is it necessary to have insulator ...
0
votes
1answer
85 views

Do soldering glasses protect eyes from capacitor explosion

I am concerned about safety while working with electrolytic capacitors. Can I use soldering safety glasses to protect my eyes while working with electrolytic capacitors?
58
votes
7answers
9k views

Can a bird, previously at earth potential, get electrocuted by landing on a powerline at high-enough voltage due to the initial “equalization charge”?

At the voltage levels of typical overhead transmission lines in the US, a bird can land on one and be just fine (as long as it doesn't do something like spread its wings and touch a tree or something ...
0
votes
3answers
105 views

why does the model s use multiple batteries?

The Tesla Model S and NASA's Robonaut both use a battery pack that consists of an array of hundreds of battery cells. Why don't the engineers just create one giant cell?
0
votes
1answer
169 views

Wi-Fi controlled light; 230VAC - 12VDC/3.3VDC

I try to connect an ESP8266-12 and a 12V RGB LED strip to 230V AC. Based on this link, I've came to the following scheme. This will also be the first time I will etch a PCB myself. The partlist will ...
0
votes
1answer
60 views

Use a steel welding table to ground yourself from electrostatic discharge (ESD)?

I have a large steel welding table that I have been using as a work station to solder together my own custom PCBs. I have been using my anti-electrostatic discharge grounding bracelet and connecting ...
0
votes
2answers
521 views

What happens if you put the connector of a live charger in your mouth?

So what exactly would happen if you put the connector of a plugged-in charger in your mouth? I am sure it is a bad idea but can it really hurt or even kill you? Some posts on social media led me to ...
1
vote
2answers
161 views

Can I use a 25 meter LED stripe with a single power adapter?

I have 5 stripes of 5m length and 300 RGB LEDs (type 5050) each. One LED consumes about 20 mA at 12 V. Therefore, my whole 25m setup would use about 30 A. Is it safe to connect the 5 stripes series ...
0
votes
2answers
125 views

Plugging in an oscilloscope in a land of non-grounded outlets

Background: I have only one outlet in my house that remotely approximates a proper equipment grounding conductor (it's bonded to the mains ground point via the armor of 50s vintage AC, which is better ...