*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.

learn more… | top users | synonyms

1
vote
1answer
7 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
38 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
777 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
24 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
39 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 ...
4
votes
1answer
57 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
0answers
115 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
60 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. ...
0
votes
2answers
46 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
68 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
32 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
93 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
36 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
66 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
71 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?
56
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
103 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
92 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
52 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
1answer
190 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
103 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
105 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 ...
1
vote
1answer
93 views

Are small clay capacitors pose any health hazards?

I'm making a small activity with children where we will be using capacitors and resistors to make jewellery like earrings. Do they contain any materials that pose a skin or otherwise health hazard?
1
vote
2answers
572 views

Multimeter into wall sockets

If you placed one of the multimeter's probes into the hot slot of the wall outlet and touched the other probe to your skin while grounded, for example to some dirt outside, would you get bitten by the ...
2
votes
1answer
100 views

Ground impedance monitor circuit design

I'm trying to design a ground impedance monitor. The idea is that the equipment in question needs to disallow operation if the ground wiring is disconnected or the connection is poor quality. This is ...
0
votes
1answer
90 views

Class II isolated power supply (wall wart) — referencing the output to mains neutral?

If you connect the - terminal of a Class II (isolated) wall-wart-type power supply to the neutral of the mains circuit feeding the wall wart, will that cause any damage or hazards that I should be ...
8
votes
6answers
2k views

How To Know If a Fuse Will Work Properly?

I want to know what kind of periodic test we use to test if a current-limiting fuse will normaly open and protect an electronic circuit (a battery charger) if a failure occur (short circuit or over ...
0
votes
1answer
50 views

Using a ferroresonant regulating transformer as an isolation transformer

I'm looking to use a (surplus, NOS) Sola (catalog number 22212) ferroresonant voltage regulating transformer (120V primary and secondary) as a low-power isolation transformer (4A) in case I need to ...
0
votes
4answers
141 views

Providing house wall switches with 3.3v/5V supply?

It's a bit non-technical, but I'd love to hear the opinions of the pros. I'm trying to figure out what is the best way to connect my home's wall switches (lights, etc.) to 3.3V/5V. The plan is the ...
0
votes
1answer
66 views

Safety in a capsense lamp

I'm playing around with the idea of adding a capacitive sense switch to an all-metal lamp, and have some questions around safety as I'd, obviously, prefer not to turn the whole thing live. In the ...
0
votes
1answer
66 views

Rewiring a 12V charger

I have a Windows tablet with a charger which crapped out. The old charger was 12V / 1.5A - fairly standard but it had a rare tiny pin connector. Rather than buy a new charger, I decided to cannibalise ...
0
votes
2answers
78 views

Can I use aluminum tape or naked two paralleled striped cables to connect parallel LED strips?

I need to parallel connected couple dozen cut LED strips. The total current reaching them won't exceed around 2 amps. My constraint: I can not order any more components for the job. My tools: ...
0
votes
2answers
74 views

Building a prototype rig with naked boards and wires (running 24V, 3.6 A): how to be safe?

I am building a prototype rig. It includes: 1) A "naked" 24/48 V motion control evaluation board. 2) A I=3.6 A stepper motor. 3) A power supply. I wired up the motor to the board with four wires (A-, ...
0
votes
1answer
119 views

Resistance Wire Circuit Safety Around Water

I'm working on a project that requires heating of a copper pipe with water running through it. I'm aware that this is a common issue by itself but as there will be people working around the system ...
0
votes
1answer
80 views

What is the maximum voltage of a Lithium Ion Battery

My question is about the maximum charge voltage of a Lithium-Ion cell. I have charged my battery pack with 8.4V (the maximum voltage). The pack is a Samsung ICR18650-26F. The pack has a smart ...
3
votes
1answer
78 views

Safety when charging two LiPo cells in series

NOTE: I am asking this question because I am new to this subject, and I want to be sure about what I'm doing before I go out and buy parts. I am making a really fancy watch with an OLED screen, ...
9
votes
2answers
346 views

I just blew a capacitor. Now what?

We worked two years on and off on this project at my friend's place. Finally we finish, I take it home. There's a power supply unit but it can't be connected directly to mains, it expects some lower ...
2
votes
2answers
128 views

Is a capacitive touch screen safe to use?

I was reading about capacitive touch screens. I understood that your hand picks some current flowing on screen. That sounds alarming. Is it safe to use a capacitive touch screen, since it picks small ...
0
votes
3answers
79 views

Can I use a switch rated as 250VAC 25A to switch 50VDC 25A?

I am looking for a switch that can handle 25A continous current, the voltage will be maximum 50VDC, most often about 46VDC, and it will be used to switch on two dc-dc converters that have no load ...
0
votes
6answers
195 views

Are unearthed metal cases actually unsafe?

Take a look at this picture: It shows that if there is a fault with a device, current will flow from Live to Earth, hence you don't feel an electric shock. However, I don't completely understand ...
2
votes
0answers
75 views

IEC 60079 Explosive Atmospheres Compliance

I'm wondering whether anyone has some experience with designing electronics for compliance to IEC 60079 Explosive Atmospheres. I have designed a device to be installed in silos facilities which are ...
0
votes
1answer
49 views

Safety advice for best EMF detector and body shielding for UHF RFID reader

I've got a UHF RFID detector (860 to 960 MHz). I'm just getting into configuring the power output but I think I've been testing it at about 20dBM, I might want up to 30dBM. I'm concerned about my ...
1
vote
2answers
183 views

The safety of the capacitor

I saw this material for making capacitors (http://www.capacitorfilm.com/web/enproduct.aspx?ch=64). It said capacitor with the material is very safe, does anyone know what is the principle under which ...
1
vote
4answers
386 views

Can a current be induced in an HDMI cable that runs parallel to a 120v AC cable for 15 feet?

I just went to go unplug an HDMI cable and got shocked from the end of it! The only possible causes of this that I can think of are that the receiving or sending end of the long (50ft) HDMI cable is ...
2
votes
1answer
60 views

Is there anything besides power factor that determines the max CFL that can be used in a socket compared to the max incandescent for that socket?

When shopping for lamps recently, I've noticed that the sticker on the socket says something along the lines of "To reduce risk of fire, use maximum 60 watt incandescent or 13 watt compact ...
1
vote
1answer
104 views

Current Leakage calculations regarding shock hazard. A complete picture?

There is a quantity called current leakage which has always confused me. By reading various definitions, it seems to be the current flowing through the ground circuit of a device (whether this be an ...
1
vote
1answer
228 views

USB current limiter and under/overvoltage protection

I know recent motherboards already provide these, but lately USB ports are also available in many different gizmos (smartphone chargers, TVs, standalone players, etc.), which I am often tempted to use ...
0
votes
0answers
56 views

Needed help on earthing grid mat installation

I needed knowledge about earth mat installation for underground metro. I am not sure if a test reference electrode could be used for two earth mats. We have limited space and I want to cut off some ...
0
votes
1answer
485 views

Winding a Toroidal Transformer

I have a toroidal ferrite core which has an outer diameter of 15 cm, inner diameter of 11 cm and height of 4 cm. I want to use it to make a transformer which takes in mains voltage (240V) and outputs ...