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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Should I connect a small DC motor directly to the mains without an isolation barrier? [closed]
I recently found out I'd need to pay upwards of $2k in order to supply my entire house with automated blinds. I feel like I can definitely do it myself for a fraction of the cost.
For this purpose I'm ...
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Can we charge a 12S LiPO battery through a DC safety switch?
I'm working on a robot that uses a 12S battery as its main power source. The problem is that wanted to add a short circuit protection and an overcurrent protection, so added a DC automatic safety ...
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Making a flashlight watch
My son has a rare genetic disorder (nyctalopia) in which the rods in his eyes don't work and so he can't see anything in dim light. I've seen him very confused and scared in environments where I can ...
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Difference in Li-ion battery safety management for RC models compared to other applications
As generally known Li-ion batteries (whether pouch or cylindrical) may catch fire but depending on the application I see completely different attitudes of the users:
Consider as one group RC car ...
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Safety of dual male / single female Y cords
On Amazon there are Y cords with two male plugs and a single, higher current female socket. These are advertised as providing a way to power equipment with higher current demands than a single outlet ...
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Why are three pronged plugs more preferred than two pronged ones?
I get that three pronged wires have the earthing wire and all but unless we plug it incorrectly or something along those lines, two prongs work just fine right?
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Is touching the mains neutral dangerous? [duplicate]
this is supposed to represent a house wall outlet.
I think it should be yes because adding a resistance between neutral and the ground will make a potential difference between them.
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How does this EEG safety circuit work?
I'm trying to understand the following circuit, which I found in this document (on page 5). The purpose of the circuit is to go between a set of EEG electrodes and an EEG signal amplifier, and protect ...
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Do HVAC capacitors have a safety rating?
If I place a capacitor directly on the 120V home power line,
someone has probably been careful in choosing its safety rating. The
most important thing to avoid is end-of-life damage in which
the ...
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How to safely avoid earth cable? [closed]
I'm a software developer (in the uk) and I've been sent some hardware to use as part of my testing, but the way the non-uk manufacturer is telling me to wire it up sounds very sketchy to me.
Its a ...
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What could be the potential dangers in this circuit?
What are the possible hazards with this circuit? There is a possibility that the D7 is not present and the point where D7 is connected would be touched.
R1 and R2 are 25 W resistors with voltage ...
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What assumptions are made by UL when they equate 30Vrms to 60Vdc for LVLE circuits?
UL defines Low Voltage Low Energy circuits as "A circuit involving an alternating current
voltage of not more than 30 volts, rms (42.4 volts peak) or a direct current voltage of not more than 60 ...
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Why are high-voltage circuit breakers not automated? [closed]
I came across a video from Ontario Power Generation about them using a fancy Boston Dynamics robot to trip a high-voltage circuit breaker because it’s too dangerous to do it manually.
I was interested ...
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Is an AC/DC converter with no visible fuse before the transformer inherently dangerous?
I've been using a generic, unregulated mains AC/DC converter (wall-wart) for a very low-power project. It's output was a bit prone to 50 Hz ripple, so I opened it up to investigate how the circuit ...
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Color Code for Fusible or Flame Retardant Resistors: Data Sheets, Standards?
In the context of the repair of European audio and video gear, made by companies like Grundig or Philips, I come across "safety" resistors every once in a while, i.e. flameproof or fusible ...
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Is it an issue that type F outlets are not polarized?
A lot of European countries use type F outlets that are not polarized, i.e. you can plug in both orientations.
This means that there is a big risk (50%) to invert live and neutral.
Is that not a major ...
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Grounding / earthing more than one places
My home earth pit is very old and it's located at the front of the house. When checking the line and neutral I am getting average 250v. When checking the Line and the Earth, I am getting 238v.
Now, I ...
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AC-DC Schematic - Is this a Death Capacitor [closed]
Is this a death cap? I think it's not a death cap because it doesn't connect to the DC ground, but I'm not 100% sure.
Image Source: Hi-Link HLK-20M24 Datasheet - https://www.rhydolabz.com/documents/...
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Can I run a fuse block on different power supplies connected to the same terminals, depending on mobile vs. AC power availability?
I am wiring a trailer lighting system and I want to be able to run off AC power when parked at home, but run on a AGM deep cycle battery when AC power is not available. I've attached a drawing of the ...
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PCB AC/DC Converter Circuit Protection - Australian Requirements
What circuit protection and other requirements are needed in Australia for a mains (220V) to 12V AC/DC converter on a PCB?
If it's relevant, the loads are behind additional switch mode supplies which, ...
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How do you properly monitor temperature in a PCB for safety?
I am building a PCB board and it is almost done. I want to add some safety features like temperature sensing for when the board gets too hot it will turn off the system. If I use only 1 temperature ...
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Do power strips need to have a breaker?
In North America we commonly use power strips to connect equipment to the building.
https://en.wikipedia.org/wiki/Power_strip
I noticed that some power strips have a circuit breaker, and some do not.
...
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Is USB-C unsafe in humid/water conditions? [closed]
We had a case in France of a teenager who died by electrocution while taking a bath when his phone that was being charged fell in the bathtub (as reported by the press).
How is it possible taken into ...
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Possible downstream dangers of common 5Vdc power supplies
Let's say you have a 5Vdc/2A power supply that is hooked to some kind of power transformer or DC/AC converter that generates 120V+. The example I am thinking of is a nixie clock device that is powered ...
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What is the safest and most noise free grounding method floating or non-floating for audio plugs & circuits on 2U aluminum case and SMPS
I have read countless documents and viewed schematics on this subject but am still confused when it comes to physically building a box and running all of the wires correctly and safely.
I drew a very ...
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What is the alternative for a capacitive power supply? [closed]
I am trying to make a UPS, which will need to pass safety regulations. I need to detect:
When the mains AC voltage is present
When the mains AC voltage is under/over voltage
I thought of using a ...
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How to tune a safety charge pump
I am designing a charge pump that will enable a relay when the charge pump is energized (inspired from this answer). The relay is part of an emergency stop system and the charge pump is used to check ...
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What safety measures should I take during a high voltage test?
I am planning to do a test with 800 V DC system in the lab. I have taken the high voltage safety training but it's my first time working with high voltage so I want to make sure that I am taking all ...
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Looking for an indicator light for 60-330V
I have a large 330V cap bank and I would like to add some kind of indicator light that shows when it is charged.
Ideally the indicator would:
Not rely on external power.
Be visibly lit from 60-330V
...
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Does <600V Research Environment require safety training? [closed]
If working in a lab on electronics with capacitors and stored energy, I understand there can be hazards with energy discharge, electrical shock, burns etc. We have voltages up to 400V.
Is formal ...
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What fire tests are done on power adapters/chargers?
I was curious about the fire risks in using a typical AC-to-DC wall adapter
(e.g., this)
and went to the UL website
to learn what exact tests were done to get the "UL LISTED" stamp,
but I ...
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Switch Current Rating vs Inductive Motor Power Rating
I've got a single phase inductive motor rated at 1.1 kW, 220 - 240 V, and 7.1 A.
Can I safely connect this motor to a WiFi switch rated to handle 100 - 240 V and 10 A?
Clearly the switch can handle ...
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Using clothesline steel core wire rope for AC and DC
As I am currently in a war zone, I don't have many options for cabling.
I found this clothesline (steel core plastic wire rope) that appears to be one mm of diameter (steel core diameter.) 13 meters ...
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What is the safest rechargeable battery?
Lithium-ion batteries are commonly used today. What batteries (including those in the experimental stage) are safer (less likely to ignite due to damage, less harmful to health, and more stable) than ...
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"buzzing" sensation from a touch dimmer when touched with wet hand
My house has the above touch dimmers from the late 70's or 80's. They usually give off an imperceptible buzz or no sensation when used.
Today I unthinkingly touched one with a wet hand and felt a ...
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High reliability, automatic reset, enable switch
I am currently facing the issue that I am currently working on a subsystem for a high power industrial automation system. The panel of this subsystem consists of a lot of components, however here only ...
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Are loose 18650 batteries safe? [closed]
Are loose 18650 batteries safe?
In some countries they are about the most common type of battery on the market.
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Correct configuration for adding an earth terminal block?
I have a small motor controller test board setup like the diagram below:
A few loads such as a motor controller, and some switches are connected to the live and neutral terminal blocks for power. ...
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Why two EMI Y-capacitors in series between primary and secondary?
Y-capacitors between primary and secondary are often used to reduce common mode noise in flyback SMPS, as explained also here.
I have read that two Y-capacitors in series are needed to be compliant ...
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Is it possible to damage your respiratory system from high current circuits by breathing in air pollutants from hot components? [closed]
I was working on a BLDC motor circuit in my apartment which has 1 small room and not much airflow. I am using up to 30V and 10A to drive the motor. Because I am still testing on a breadboard, a lot of ...
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Would 1 W of electrical power kill you?
If we have a wire, which is transporting 1 μA of current at 1 MV, the electrical power will be 1 W. If I touch the wire without properly insulating myself, will it kill me?
I read all the answer and ...
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AC step down circuit
I have a quick question about a circuit I want to build, namely a low voltage AC power source.
I attached a picture of the schematic.
Are there any safety concerns that I might have to pay attention ...
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What is the current industry practice regarding the impact of current-limiting fuses on arc flash calculations?
Suppose you have a panel. The arc flash incident energy for this panel is computed based largely on the available short-circuit current (SCCA) to the panel, and the protective devices upstream of the ...
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How do you safely measure large AC currents using a multimeter without a current clamp?
I would like to measure the RMS current draw of several house appliances, in addition to the primary and secondary side current of a step-down transformer.
Simply placing my multimeter in series with ...
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Do I need a bleeder resistor for discharging an inductor?
Pretty straightforward question, I'd say.
I know that for a capacitor I'd definitely want a bleeding/discharge resistor, and I know how to size one for that (cheat sheet for anyone curious), but what ...
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Is the voltage / power running through an exposed Bluetooth keyboard enough to be hazardous?
Unusual question and potentially not the right forum for it. Apologies in advance.
In short, I have cracked the shell off a Bluetooth keyboard and modified it (read: Jerry rigged it) to be as light as ...
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How to wire a 480 V AC to 380 V AC transformer?
I have to install a reflow oven which needs 3-phase 380 V AC to power on.
There is a transformer (as the picture shows) that came with the oven. I assume that the black wire is the "hot" ...
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How is a mains-connected medical device made safe against electrocuting me?
I am in physical therapy now. Some of the devices are connected to wall power, and used for muscle electrostimulation. The patient information states that no single malfunction can connect me to 230V, ...
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How to educate myself about PWM solar charger circuit design?
Since my previous charger said farewell today, I have decided to build a 48V 100A solar PWM charger (for LFP cells, ie. CC-CV) myself. I don't need MPPT because I have already well-balanced PV and ...
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Is this food box safe for electronics?
I want to organize some components and wiring for power distribution for a small solar panel. Voltages up to about 24 VDC, and currents up to about 3 amps. Components inside will include switches, ...
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