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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.

6
votes
0answers
514 views

Electric fly zapper - how is this safe?

My trusty electric fly-zapper broke, so I opened it up to have a look in case it was something simple. I have to say I was a little surprised by what I found inside: the capacitor reads 473K, meaning ...
19
votes
11answers
4k views

How to safely discharge oneself

At work I have the problem that I seem to collect a lot of static charge as soon as I leave my desk and return. I am not quite sure why this happens. Strangely enough the effect is stronger the ...
-4
votes
0answers
90 views

Lead Contamination in house after touching solder [duplicate]

I may have accidentally touched my laptop and keyboard and mouse and maybe my desk after soldering the one time I did and was wondering if it's contaminated with lead and how to clean/dispose of it if ...
2
votes
3answers
171 views

Lead Contamination when Soldering [duplicate]

I bought a soldering station a while back and was practicing on a kit and had the website on assembly up while I was soldering using 60/40 tin-lead solder. Should I worry about splatter on the ...
0
votes
0answers
90 views

Safe Voltage/Amperage for Soldered Wires - aka When to Crimp Instead

I have found a lot of information that circles around what I'm looking for, but nothing that directly answers it. It is possible there is no right answer.     I am jealous of the Macbook ...
1
vote
0answers
26 views

Standard LiPo battery packs & product liability

I'm designing a high-power portable product that I would like to eventually bring to market. I need to use LiPo battery packs in order to achieve sufficient energy density, but I do not think I will ...
18
votes
3answers
2k views

Health risks of exposed contact to a capacitive sensor

I want to make a wearable metal trinket with the ATtiny85 chip acting as a capacitive sensor (with the same technique that this Arduino library uses), so it can detect when it's being worn. Are there ...
1
vote
3answers
66 views

Maximum safe amperage for LED Strips

A lot of online resources never question the use of high amperage power supplies for powering LED Strips. As an example, 5 meters of low density (30 LEDs per m) WS2812B strips already use ...
0
votes
1answer
24 views

Clearance distance and resin filler

I'm designing a circuit to detect presence of AC line voltage. It's actually a very simple device with AC side made up of a 200Kohm 1W resistor and an optocoupler and a protection diode. There will be ...
0
votes
2answers
155 views

Microwave starts working when door opens - how dangerous is it?

I've just rented a house that came with an equipped kitchen, and I've found that the microwave has a rather weird behavior - opening the doors seems to trigger it to start working, which the owners ...
0
votes
2answers
56 views

Earth line safety [closed]

I am working with a conductive appliance that a user will be in constant contact with over extended periods of time and the appliance is constantly earthed. These two facts cannot change, other than ...
2
votes
3answers
381 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 ...
9
votes
8answers
7k views

Is it safe to use a DC power adapter that isn't UL Listed or CSA certified?

I picked up a 9V switching DC adapter from SparkFun a while back, but I've been hesitant to use it because it doesn't have any of the usual "safety" approvals that you normally see on power adapters (...
2
votes
2answers
80 views

Why is 100 volts or less generally “low voltage” and “safe”? [closed]

In the United States in many state jurisdictions, wiring that operates either exactly at or below 100 volts is not required to be installed by a licensed electrician, and no site plan, building permit,...
0
votes
2answers
60 views

Optocoupler isolation necessary?

The circuit diagram below shows two possible options for a circuit: simulate this circuit – Schematic created using CircuitLab The difference between both circuits is the use of the ...
5
votes
1answer
82 views

48VDC safety precautions?

I am building a bit of equipment that requires 48DVC @ 2.5A to be brought out of the metal box housing it. I intend to feed it through a piece of plastic tubing along with a sensor wire, which exits ...
3
votes
0answers
37 views

How to wire an entire room / kitchen with LED light strips? [closed]

As the question suggests, I'm looking into adding LED light strips throughout the kitchen (over cabinet, under cabinet, and kick -- I think under the countertop would be neat, but harder to hide). ...
1
vote
3answers
147 views

12v nichrome wire water heater. Is it safe?

I want to heat the contents (water) of a two liter thermos flask using a low power (50-100 watt) 12 volt DC heater. Rather than buying a tiny little immersion heater, I've got some nichrome wire ...
31
votes
4answers
44k views

Safe current limit for human contact?

What's the point below which electrical current is generally considered safe for "casual" human contact? Is either voltage or amperage more "dangerous" (e.g. high voltage / low amperage vs. low ...
0
votes
2answers
824 views

safety relays and PLCS

I am having trouble trying to get my head around using safety relays in PLC controlled machinery. I want to install a PLC into a machine that needs upgrading, it is straight forward enough, well i ...
0
votes
9answers
7k views

Dangers of capacitors blowing up

I was wondering what kind of damage a 350V, 6000uF (link to capacitor) electrolytic capacitor could do. will this kill me if it blew up next to me? I have never blown capacitors before, but I ...
0
votes
1answer
104 views

What precautions should I take to setup a home electronics lab? (Living in the UK) [closed]

I'm soon to be buying a house in the UK and would like to setup an electronics lab in the garage (attached to the house).The type of equipment I'll be using is nothing out of the ordinary: ...
51
votes
7answers
10k views

Does a dangling wire really electrocute me if I'm standing in water?

We've all seen this scenario in movies; somebody has to cross a room half filled with water and there is a dangling electric wire that shoots sparks everywhere. The poor person has to cross the room ...
1
vote
3answers
209 views

Maximum fuse rating before a MOV (varistor)

I just watched some scary videos of MOV's catching fire and I've flee'd here to ask you guys for help. I understand that it's a good idea to put a fuse in front of a MOV, considering it fails short-...
1
vote
1answer
858 views

Conductivity of water, and risk of shock? (fact checking)

Through simple researching I have discovered the unit of siemens (being a reciprocal of ohms). Now I wish to apply this to a (silly) scenario where the conductivity of tap water is 800µS/cm (from ...
1
vote
3answers
28 views

Connecting the Block AIM 5.0/2.0 auto-transformer to UK three-wire plug

I am not electrically very knowledgeable person. At the moment I am trying to connect a Block AIM 5.0/2.5 Auto-transformer to a piece of very sensitive medical equipment. The auto-transformer was ...
71
votes
8answers
12k 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 ...
19
votes
4answers
30k views

How much current can Solderless Breadboards handle?

I'm working on a project with a few stepper motors. I want to breadboard them so I know the circuit works well before creating a physical PCB. Each of the three motors is rated 2A, but I'll be ...
0
votes
1answer
95 views

Is there a safety issue with running a AA alkaline cell through 0.3 ohms?

I'm running an Electricity merit badge session for my son's boy scout troop. One of the requirements is to make a simple electromagnet. For this, I was going to have the boys take a 12 foot length ...
4
votes
3answers
110 views

Protecting against a SSR failing closed

In a project I'd like to control a heating circuit with an SSR, and I'd need a contingency plan for when the SSR fails closed, and the microcontroller cannot turn off the heating element, which would ...
2
votes
7answers
5k 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
votes
2answers
93 views

How can I power a device under test in a way that is safe for an oscilloscope?

Is it possible to power a circuit in such a way that makes it impossible to fry my oscilloscope with a ground loop? I've heard using a battery is a good way to prevent this. Is there a other way I ...
0
votes
1answer
93 views

lithium coin cells, safe to completely cover? lightweight method to protect from the environment

I am trying to make equipment to measure temperature in small mammals, probably attached to a neck collar. The collar needs to be very lightweight (e.g. <3g total) so I am planning to use a ...
6
votes
2answers
1k views

Using 240v mains on/off as input to microcontroller

I have a light switch that switches 240v (UK) mains. Instead of using that to directly control a light, I want to use it as an input to a controller board so I can also automate the lighting. (It's ...
0
votes
1answer
113 views

Bad Practice - Charging Lithium Batteries while powering circuit?

I'm using a 2s BMC to charge a 2s2p lithium battery pack (7.4v, ~6Ah). The output of the charging circuit is the same as the input - they're not separate. As a result, when I want to charge the ...
0
votes
1answer
34 views

Optimal Grounding for a PVC Dust Collection System?

It is common in woodworking (A hobby of mine) to make a dust collection system (Basically a tube hooked up to a vacuum to carry away dust created from automatic woodworking tools) out of PVC. We'll ...
2
votes
2answers
72 views

What's a safe method for determining the switching frequency of a blackbox ACDC converter?

My project uses an off-the-shelf ACDC converter that conceals design details from such as switching frequency (or SF range). It's 24 V output rated to 5 Amps. I want to measure it's switching ...
0
votes
1answer
57 views

Voltage on the grounded conductive devices when plugging in non-grounded outlet [duplicate]

Most outlets in my house are non-grounded (line and neutral contacts only). I just bought a Hakko fx-888d soldering station, and immediately noticed that touching the iron-station cable gives the same ...
0
votes
1answer
99 views

How does the iPad not electrocute people without grounding?

I've noticed for a while that my iPad had a tingling sensation when I brushed my hand along the back of the casing. I found out today that it was because the charger is not grounded, and this was ...
4
votes
3answers
88 views

If two objects are grounded, why do they still need to be bonded? And if they are bonded, why does each still need to be grounded? (fire safety)

When transferring a flammable liquid, both the container and the receptacle are supposed to be grounded and bonded. If they are both grounded, shouldn't the change on each be equal to ground? And if ...
0
votes
2answers
139 views

Reliability of STM HAL driver For Safety Critical Application

I'm working on a project which must be used in an automotive application and act as a node into the multiplex CAN-BUS network. There are number of I/O that must be actuated and some of them had a ...
0
votes
1answer
139 views

Is it safe to measure 220Vrms@50Hz on DSO directly?

I borrowed my friend's DSO to complete my project(Hantek DSO5072), but on scope it says CAT II/400V. So is it safe to measure 220Vrms@50Hz with it?
0
votes
1answer
105 views

Power supplies with medical safety approval

Regarding the data sheet of this SMPS power supply. In the first page it says: 2 x MOPP Medical safety according to AAMI/ANSI ES 60601-1:2005(R) and IEC/EN 60601-1 3rd edition Then I googled to ...
0
votes
1answer
107 views

Battery Disconnect Switch

I'm an Electrical Engineering student still new to power systems. I'm working on a project that uses a 24V and 200Ah battery bank made up of 4 AGM lead acid batteries. The batteries are supplying four ...
2
votes
1answer
178 views

Designing single fault safety into class I device

I'm trying to wrap my head around safety standards for electrical equipment. My device is medical, so for me section 8 of IEC60601-1 is what really matters to me, but it's kind of my understanding ...
0
votes
1answer
52 views

Wiring a traffic light

So I have aquired 1 light of a traffic light that I salvaged from a local dump. I want to try and connect the light to use it like a lamp, however I am a little worried by it as the connector only has ...
7
votes
4answers
3k views

Is it Safe to Plug an Extension Cord Into a Power Strip? [closed]

Just a bit of context, I am a technology enthusiast. I love everything from software to hardware, Windows to Linux, Computer to Phone, and everything in between. So, I wouldn't be surprised is my ...
0
votes
1answer
27 views

Definition of Field Wiring Terminals as in UL 499

I'm wondering if anyone can tell me where I can find the definition for "field wiring terminals" as referenced in UL 499 "Standard for Safety Electric Heating Appliances" table 27.1 "Minimum ...
1
vote
2answers
116 views

Is this a safe way to add extra current control for a DIY tDCs device?

I have put together the well known DIY tDCs-device Inthinkerator MK1, and wanted to add an extra safety feature, but I dont know if this is the correct way to do it. The original design is without the ...
1
vote
1answer
114 views

Proper Chassis Grounding

I'm starting to design things that run off mains voltage and I want to be sure that I have a proper connection from my chassis to earth ground. I've been reading a bit about proper grounding and have ...