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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Switch that is rated for 24 V and 4 A: can it endure 8 A if I limit the voltage? [duplicate]
I have a switch that is rated for 24 V and 4 A. Can this switch endure 8 A if I limit voltage? What voltage would I have to limit to? My concern would be not to melt the switch with too much power. ...
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Is the JEITA battery charging temperature standard accepted by EN62368-1?
EN62368-1 Annex M.4.2.1 mandates that the battery charging circuit shall 'stop charging' when the temperature of the battery exceeds the highest specified charging temperature (typically 45°C). ...
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How do I store a Li-ion pouch battery without any discharger or balancer?
I have a single-cell 3.7V 900 mAh Li-ion pouch battery and a 7.4V 30c 2s 850Mah Li-ion pouch battery. I want to store these two batteries (the manufacturer suggests I should store the 2s pack at 3.8V)....
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What are the dangers of a fully charged LiFePO4 12 V, 100 Ah battery in home and only used for emergencies?
I have Goal Zero Yetis 1000X & 500x (plus several other smaller power banks) with GZ's Boulder 100 Solar case and some other 100 W solar panels I've used for camping. I mainly use all of this at ...
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CAT ratings and DC voltages
I'm a bit lost about the CAT ratings (protection ratings) for oscilloscopes (and multi-meters).
There are many tables for which category is needed for which application (for example here or here,) but ...
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Is it safe to briefly short the secondary of a power transformer to measure the maximum fault current at the primary?
I have a bunch of salvaged step-down mains power transformers (220V-240V primary voltage at 50Hz), with powers ranging from a few VA to maybe 100VA. In order to use them safely in my projects I need ...
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How to design a safe series/parallel Li-ion battery pack with non-huniform cells characteristics (capacity, SOC)?
I wounder if I could design a safe series/parallel Li-ion battery pack by using different cells with different characteristics: different capacity, SOC, age.
I know that is VERY VERY VERY DANGEROUS at ...
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Persons protection: residual-current circuit breaker for DC?
I'm currently reviewing the schematics of the power supply of a robot prototype.
The 380 V AC (3 phase) is converted (isolated converter) into 320 V DC (up to 20 A).
There are only 3 wires going to ...
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Can a Li-ion pouch cell and a Li-ion cylindrical cell be connected in series?
I have two 3.7 V, 900 mAh Li-ion pouch cells, which I connected in series to provide 7.4 V. But now I want 11.1 V. Instead of buying another Li-ion pouch cell, am I able to put these two Li-ion pouch ...
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How to isolate the AM2301 sensor with a small footprint and low-cost isolator (digital or opto)?
Looking for a solution for isolating the AM2301 sensor with either digital or opto-isolator. I have space and cost constraints. Thank you .
AM2301 is accessed via a single bus / single line interface ...
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Safety around old laptop batteries
I found an old laptop with a removable battery that hasn't been used it (probably) years, maybe decades. I want to plug it in to see if it still works, but I'm not sure if it's safe to do so. I either ...
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Double insulation for battery operated device
I work for a lab device manufacturing firm. During the testing of our electronic pipette according to IEC 61010-1,the safety test lab asked why it did not have the symbol indicating double insulation.
...
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Board-mounted vs chassis-mounted fuses and maximum voltage on perforated board
I'm trying to build a circuit that uses 400 VAC mains, with a peak voltage of 56 5 V, but let's consider 625 V maximum to take into account mains voltage fluctuations.
I always see fuse holders ...
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How can I charge this battery mess? (Charging cells in series connected to cells in parallel)
I have two groups of cells, Group A and Group B.
Group A are 14 cells connected in series, with each having 1,5 V = 21 V.
Group B are 7 cells connected in parallel, with each capable of 3 A = 21 A.
I ...
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Is cooled-down lead after soldering safe to touch?
I’ve found one topic on this forum about this but it doesn’t answer my question fully.
From the information I’ve gathered, you should wash your hands after touching lead, even if it’s a cooled-down ...
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Can a dual pole (mechanical) relay switch HVAC and LVDC at the same time?
As I understand it, a dual pole relay is one which (mechanically) switches two independent circuits.
Is it safe to use such a relay (I'm looking at an Omron MJN2CE, specifically) to simultaneously ...
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How much should I worry about battery fires?
I have a Li-Ion battery (built into a small spot welder device)
with 5Ah capacity (and 650A short-term current drive) that I will
probably not use for the next 3 months. It's now charged to
about 50% ...
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Stray voltages on home appliances in unearthed electrical system
Using a simple multimeter I have discovered around this home (what I may be mistakenly calling) "stray voltages", i.e voltage potentials across appliances' metallic parts that should not ...
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Can I use a plastic water tube as resistance to protect bathing people within a safe voltage?
Suppose home water has a resistivity of 2 Ωm, home electricity is AC 220 V, and human body in shower has a resistance of 1 kΩ.
Then a resistance R = 8.2 kΩ, which is a plastic water pipe of 1.29 m in ...
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Mains power supply safety
Curently I'm working on a design (for my own domestic use only) which is to be supplied by 230 V/50 Hz mains.
The IEC cord will be connected too one of these:
Mains Filter with Fuse
After that, the ...
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What are the safety and OSHA protocols involved in water in electrical switchyard?
Just saw a meme online:
Is this safe? What could go wrong?
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How to protect a power supply
Enthusiast here, with no particular electrical engineering knowledge.
I have ordered a power supply, similar to this one in the way it is built:
Here are the specs:
Input is 230V AC
Output is 48V DC ...
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How can I check if I'm properly grounded?
I figured that if I used my trusty ol' calibrated Fluke 77 multimeter and:
Set it to Ω measurement
Measured between the ground terminal of an electrical outlet and a bare metal pipe fitting on a ...
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Toggling 230 V relay on custom PCB design - general design and safety
I am about to design a custom PCB that is supposed to switch a 230 V inductive motor with a 750 W rating over relays.
I have the "option" (since I happen to have them around) to do this ...
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How to properly wire fuse block, DC-DC converter, and load
I have a battery, a fuse block, and three PCs (Raspberry Pi.)
Is it better to have three separate DC-DC converters in front of the fuse block with the battery directly connected to the fuse block or ...
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What is the potential of earth relative to mains live and neutral? [duplicate]
I'm confused about the theory of earthing in mains electrics. In particular, how the potential of "earth", the ground or literally the soil beneath my feet relates to the live and neutral ...
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Step-down transformer's neutral pole is referenced to hot! Is this unsafe?
I have a 220 V -> 110 V AC "wall wart" shaped step-down transformer with a plastic body. The input has an ungrounded three-prong plug (the ground is plastic) and the output is a polarized ...
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Can I wear ESD protection while handling a live PCB?
Are ESD wrist straps, gloves and table mats safe to use while handling a live PCB or a turned on Raspberry Pi, for example?
What I intend is to protect the components against static discharges.
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Double insulated PSU to replace batteries
I am building a small power supply with a linear regulator that can be used in place of 9 V blocks. Like a battery, it needs to be floating and hence I want to build it according to double insulated ...
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Safety using a step-down transformer (240VAC to 110VAC) with a heated pad?
Sorry if this is a newbie question, but I'm trying to be more safe than sorry and don't have a lot of experience with high-voltage electronics.
I have a special small heated pad (for use on the body) ...
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Are surface mount or through hole connections more reliable for safety critical applications?
While obviously factors like safety certifications and margins of error are more important when it comes to safety critical applications, e.g. aerospace, I saw an article that said that one of the ...
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Are those electric fields dangerous?
Is 8.6 amperes per meter, 70 microtesla, 0.70 gauss, 695 milligauss, safe on long time exposure?
I am just worried.
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LiPo Battery (parallel cell) Protection - Fuse Selection to Support BMS
I'm designing a LiPo battery and I'm struggling with the protection, or more specifically, the fuse selection. Can I please have some help? This is a really convoluted problem with a lot of factors, ...
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Safety circuit to control maximum voltage
I am looking for a way to control an analog signal from another system that changes between 0-1 V.
The user could define the maximum voltage value, for example 0.793 V (the analog signal has ...
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Balancing Li-ion cells
I am designing a power management board. The board should be able to distribute the power across a system and manage the power coming from a solar panel, while recharging batteries with excess power. ...
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Are very old CRT oscilloscopes possibly dangerous because of their X-rays?
I'm a novice who's looking for a very basic oscilloscope. I found some on Ebay. Probably I'm much too careful, but I'm wondering if cathode ray screens from oscilloscopes of the 80s may leak ...
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Best switch type to turn off the mains voltage to electronics [closed]
Basically I am making a reflow plate, that requires mains voltage for the heating plate. I have a basic knowledge of mains voltage and am just trying to make the product as safe as possible, by adding ...
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How to test an anti-static mat that says \$10^7 \sim 10^9 \Omega\$ surface resistance
I just bought a well-made mat that says surface resistivity is 107 ~ 109 Ω.
The multimeters on the market test up to like 20 MΩ.
If I buy a multimeter to test it:
If it displays infinite, I won’t ...
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Insulation safety ratings (working and withstand voltage) of fiber optics cables
I'm trying to build a high voltage optocoupler to implement galvanic isolation between a high voltage supply and its control signals. Since the working voltage is several kilovolts, it's beyond the ...
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Cable jack melted
I've build this circuit:
My power supply is 12 V, 4 A and my load is rated at 1 A and the melting point of the cable I'm using is 300 F.
I found the cable has melted at the point of contact between ...
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Testing if a user-facing component of an appliance is live - check the work of my apprentice electrician friend!
I have a friend who is an apprentice 'sparky' as we call them here in Australia.
I asked him to test part of a heater I fixed a while back.
It no longer has a knob to turn it up and down, but instead ...
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Could ground faults in the same building affect my anti-static grounding plug?
I have some tools for anti-static purposes for repairing a computer: an anti-static wrist strap, an anti-static mat, a grounding plug on which only the earth pin is metal (the hot and neutral are ...
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Which parameters should I consider to choose safety capacitor?
I know the X and Y capacitors, how they are connected and why they are used but I am not sure about selection criteria and how they are exactly affecting the signal. I would appreciate with some help ...
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LED - Downlights/Recessed Lights - Quality, Safety [closed]
I been looking to upgrade old recessed can lights with "modern" LED slim potlights, Market is flooded with different brands.
I went out and purchased a bunch of LED lights, removed the ...
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How do I cut a electric wire, that is still working? [closed]
Must I wear some kind of gloves, are cutters with plastic cutters enough for safety.
I heard one should wear rubber boots. Are there other safety tips?
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Is it safe to parallel a 2 A breaker with a 10 A breaker in a testing situation?
I need a testing rig when repairing mains appliances.
My initial idea is a DIN rail system with one receptacle and two breakers: one 2 A one for low power stuff and a 10 A one for some high power ...
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Attach thermocouple to a PFC inductor
The inductor I am talking about is simply a toroid. I am attaching a thermocouple junction to this component with help from thermal paste and aluminum tape.
Anything I should be careful about in this ...
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Does current have to return to its source?
I am not the most knowledgeable when it comes to electricity, so apologies if my questions lacks necessary information that is needed to get a good answer.
I work with 3 phase electric motors, and I ...
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What is the use of a P-channel FET on a power line?
I was going through a schematic of one controller. I found this circuit for the VIN pin:
What is the DMG2305UX (Q1) P-channel MOSFET used for?
I have read that MOSFETs are used for reverse polarity ...
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Can I run resistor at a power higher than rated if I have external cooling?
Say I have a 1 ohm 100 W resistor that can work properly in still air. I now want to run it at 150 W, but I am also using a strong fan to cool it down to its usual temperature. Is this okay?
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