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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124 views

Can I use this US extension cord in Europe? [closed]

Long story short: I need an extension cord to charge my EV when the standard charger does not reach the socket. I spent hours researching what options I have and most review websites I found were US-...
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0answers
52 views

Is it safe to supply a 12V appliance with a 19V adapter? [closed]

I have an electronic back massager that has a 12V input. Its adapter stopped working today morning, so I used a 19V laptop charger which connected to it perfectly and then I used it, but I'm second ...
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1answer
86 views

USB Power Inside of Freezer / Fridge

Background of the project: I am doing my own DIY Keezer (keg freezer) which basically turns a chest freezer into a fridge that will hold kegs with the assistance of a temperature controller. The ...
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1answer
60 views

How to separately charge two LiPo batteries wired in serial?

I would like a circuit where 1) two protected LiPo batteries are wired in serial to power the load; and 2) when external power is plugged in the load is disconnected and the batteries are charged ...
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1answer
27 views

How do you do back-voltage testing on USB 3.0?

There is official documentation (Appendix F) on how to do compliance testing on USB 2.0 devices to ensure there is no back-voltage to hosts. Is there an analogous test for USB 3.0? My assumption would ...
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1answer
72 views

Emergency brake BLDC motor [closed]

I am redesigning a flawed safety system for an autonomous robot. The robot will drive alongside humans and roads, thus it needs redundancy. The braking is achieved in two ways: The motor controller ...
1
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1answer
43 views

Replacing laptop power lead with moulded connector [closed]

I have a laptop whose power supply consists of two parts: a lead with moulded BS1363 plug (3A fuse) on one end and an IEC C5 connector on the other; and a transformer which takes the C5 connector and ...
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2answers
109 views

Can a railway system reasonably use both normal rails as power rails?

I have a question about electrified railways that seems obviously unsafe, but first you have to know how the "normal" third rail works. Third rail power comes in over a middle rail and is ...
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2answers
42 views

Is it worth adding short circuit protection to a 5V string of WS2811 fairy lights?

I'm making a control box to drive a string of 5V RGB fairy lights. Each RGB LED has a WS2811 driver chip. All the LED drivers are in parallel. The positive and negative leads along the length of the ...
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1answer
128 views

What dangers do I face in working on this radio?

I bought this radio. I will be putting a microcontroller into the box, and connecting the radio's tuner, speaker, volume control and on/off switch to the microcontroller. So, I will not be plugging in ...
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3answers
72 views

Is it safe to attach COB LED light strips to a desk with a metal frame?

I am kind of new to electronics, and I wanted to make sure that I am not doing something dumb. My SO and I work on one big desk, 177 inches / 4.5 meters long. It has a metal frame and a MDF desktop. ...
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4answers
110 views

Methods for high current DC motor emergency cutoff

I need to add a secondary means of cutting off power to a motor for safety reasons if a state change is detected on a 3.3V logic level signal while it is operating. The requirement I have is that it ...
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1answer
82 views

High Voltage(3kV) Capacitors & Relays -- Safety and Recommendations [closed]

I am currently working on a quadrupole ion trap based on a DIY manual published by CERN. Link: https://scoollab.web.cern.ch/3d-printable-quadrupole-ion-trap Long story short, after failing to get my ...
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5answers
136 views

How can a mobile phone being charged kill by electrocution?

We have in France a wave of warnings about using a mobile phone while being charged in humid environments (or when taking a bath). A charger is plugged directly into the wall socket and the charge ...
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8answers
976 views

Why is there not lots of current flowing on a house’s grounding electrode?

If I remove the plate of a wall outlet, and touch the hot screw, I’ll get a shock. The potential difference with the ground is enough to send some current into my hand. Importantly, this happens even ...
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2answers
60 views

Best user safety for PTC heater: 230VAC or 24/48VDC?

How to design the following system as safe as possible? The components are: mains 230VAC enclosed control box, grounded custom connector: the user plugs/unplugs the heater cable pushbutton: the ...
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5answers
114 views

How to safely *temporarily* wire 120v?

I am wondering if there is any device to safely create a wire connection? More specifically, here is my most recent situation: troubleshooting a noisy 120V electric motor (fireplace blower). The motor ...
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2answers
528 views

Can soil carry enough current to electrocute you?

I'm a bit worried about using electricity outside, but I see that pretty much everyone has some type of outdoor lighting, so I might just be paranoid. Anyway, I was wondering how dangerous outdoor ...
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2answers
115 views

How to make an A.C. voltage source (low voltage) with desired frequency from a D.C. source?

I want to make an A.C. source with desired voltage and frequency (adjustable) from D.C. sources like batteries. I tried to search circuits on the internet, but as I am relatively new in the field (...
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3answers
2k views

Li-ion 18650 safety

Background: I would like to build a battery pack out of 18650 li-ion cells (3S2P). Safety is my absolute priority. Questions: Here is the list of all safety measures that I could think of: Use ...
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0answers
112 views

When to use a high voltage resistor vs multiple standard resistors?

Looking for the smallest & most reliable method of dropping 360V down to ~1V for a PMIC feedback pin. Reliability is probably the most important variable here. Question: In general are we be ...
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4answers
113 views

What is the maximum sustained and peak current of a AAA battery?

I'd like to create a small circuit that I can use to power my headphones off a USB port's 5V to avoid having to deal with AAA batteries (even rechargeable batteries can get lost, etc.). To do this, I ...
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0answers
47 views

Sufficient electric safety protection with MOVs?

I am developing a PCB that will carry 32 A currents. In order to protect the rest of the circuit and the 3 phase load I have added some protective measures to suppress transient voltages and short ...
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3answers
471 views

When do I need a protective earth?

My company is developing a new handheld power tool. We are a rather inexperienced team and I am not a electrical engineer but I am concerned about the safety of our customers. We are located in ...
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1answer
92 views

Oscilloscope safety, measurements for safe probe ground connection [closed]

I have several oscilloscope safety-related questions. The questions come after a bit of background information. Please let me know if you think there's something iffy with the background information. ...
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1answer
59 views

EVSE method of monitoring PE line in aCcordance with IEC 62955

I would need some opinions/help regarding if my circuit is acceptable for its purpose. In order to meet strict safety criteria, my circuit needs to be able to detect if there is high voltage present ...
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0answers
75 views

Is this USB Hub 3.0+2.0 hybrid safe to use?

So I just bought a USB 3.0+2.0 hub hybrid. When I check the PCB, the pin out is new to me (see photo). From host, two of the USB 2.0 data lines (red lines) went straight to the hub IC, then from the ...
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2answers
72 views

How can I provide time-controlled current protection?

I need a component name or solution. I have a fan motor that I run with AC. I am controlling with MCU and driver. Operation logic: 0.75 s on, 9.25 s off. My circuit works flawlessly with this logic. ...
2
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1answer
92 views

Safe Enclosure for Mains Powered Project

I am working on a project that uses 120VAC power. I have made a lot of enclosures for low voltage projects in the past, but this is my first high voltage project that needs an enclosure. I am ...
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2answers
91 views

Safety Capacitors; Is it OK to fit an X1 in place of an X2?

I have a PCB which has a 0.010uF X2 safety capacitor fitted. It seems the exact part is now obsolete. Would it be acceptable to replace this part with a 0.010uF X1 safety capacitor? I believe a ...
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0answers
108 views

Why does my lamp say "Use max 60 watt Type A OR max 10 watt LED?"

I'm really intrigued by the label on a new lamp. It says: Caution: To reduce the risk of fire, use MAX 60 watt type A lamp OR use MAX 10 watt self-ballasted LED lamp or lamp adapter. Now I didn't ...
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0answers
53 views

Coin battery for powering the RTC while MCU power down: is safe for ATEX ZONE 2 or DIV2 in hazardous environment? The Box is heavy duty IP67 sealed

I wish to use RTC which keep powered by a coin battery (i.e. CR1225) while disconnected from +5V power. The box is heavy aluminum diecast with IP67 sealed. I was concerned about using coin batteries (...
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0answers
72 views

Heat concerns using 12/14 AWG wire for 30A 5V DC power over shorter distances?

I’m hoping for some advice on wire gauges in practice with respect to heat/safety. I am planning an LED strip setup and have created the following diagram: The setup is designed to be modular, A ...
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1answer
77 views

Risk of getting shocked by ECG leads? [closed]

I have recently come into possession of a GE patient monitor (Eagle 4000) which looks structurally sound, probably decommissioned because of its age. It seems to work without a hiccup but I remembered ...
3
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2answers
324 views

Component name - breaking circuit based on ambient temperature

I'm trying to add a (resettable?) fuse to a circuit (24 VAC) which breaks a circuit when ambient temperature reaches a given temperature (say 60° C) in addition to current crossing a threshold. All I ...
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0answers
74 views

How to charge 8S battery pack with two 4S BMS circuits?

I recently made 8S battery pack out of 18650 cells (4.2V each) and I am worried about connecting it to BMS. Some time ago I asked what BMS should I get (well, I asked if i have to have some BMS at all ...
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1answer
173 views

Small electric shock from toaster when plug is ungrounded [closed]

I have a toaster which is supposed to be grounded. Some sockets in my home are not grounded and some are grounded. When the toaster is connected to an ungrounded socket, the metal casing could cause a ...
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2answers
148 views

Is a 350VDC capacitor safe for rectified 240VAC?

I need some capacitors to smooth out rectified mains (long story short, I see 50 Hz light flickering, so I need lights running on DC instead). While looking, I saw that 350V capacitors cost me only a ...
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3answers
76 views

Bench PSU "Ground-Earth-Reference" connector - what's it called?

I have need of some of those little metal links that let you bridge between GND and Earth posts on a typical benchtop-PSU. But I'm damned if I can contrive a google search that yields any useful ...
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2answers
110 views

Is it safe to connect Neon indicating lamps with resistors to defrost timer and other fridge components? [closed]

I want to connect some indicative LEDs neon lights pulled from the switches of a multiple ways extension cord to the fridge. Initially the defrost timer, then later all parts and wires individually so ...
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2answers
75 views

Can I properly charge 9S battery pack without a BMS?

I have a small problem with charging my battery pack. The first problem is that I do not even know if it really is a battery pack. It’s just eight 18650 cells connected in series in order to get +- 33,...
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2answers
38 views

PAT testing of extension leads and RCD protected sockets (UK - industrial type environment)

Not 100% sure this question belongs here, it was a choice between this stack and the home improvement stack but I have posted it here as it's about electrics in an industrial environment. In an ...
2
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1answer
162 views

Current characteristics of ISO7421 isolator IC

I am using an ISO7421 IC for serial communication isolation. I have read the datasheet of the ISO7421. I am not able to understand the current characteristics given in the datasheet. My concern is if ...
0
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1answer
69 views

Mains safety shutoff

I have a problem. I have a sensor in a piece of equipment that needs to switch off that equipment if it detects a dangerous gas. The equipment must remain off until a manual reset is applied. What ...
1
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1answer
62 views

Electrical safety best practices for a transformer secondary

If I'm building something with a transformer that has mains on the primary and something like 24VAC, or just any voltage lower than mains on the secondary, what are the best practices in terms of ...
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4answers
3k views

Why might a low-cost soldering iron die after short use?

It's been a while since I have soldered, so I bought a cheap unbranded soldering iron to use while I re-familiarised myself with the skill. After a few weeks of use, I turned it on just now and it ...
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0answers
46 views

Battery made of Li-ion cells assembly

Do you see any issue (feasability, safery, ...) about assembling a battery pack with 10 Li-ion 3.7V 2600mAh cells (put in parallel) having their own individual protection circuits (overcharge and over ...
0
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1answer
58 views

Contacts on Safety Relay

I'm trying to replace this Banner part (an E-Stop Safety Relay) with a Siemens part that will do the same thing. Originally, I had picked this replacement, but became concerned when looking at the ...
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1answer
35 views

LED Circuit Safety Next to Paper

I'm making a bookshelf diorama out of a old book, and I want to install an led light circuit that turns on when the cover is opened. This means I'll be running small wires through and next to paper, ...
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1answer
59 views

Switching on high side and low side of the load

I am working with a safety related circuit that controls turning on/off load (solenoid of the hydraulic valve). I am wondering how I could implement this type of circuit using MOSFETs. Here is an ...

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