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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.

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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 ...
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40 views

How should I clean up a mobile phone after a punctured lithium-ion battery? [on hold]

I recently removed the battery from my old iPhone 6 and in the process, I accidentally punctured the battery, making some smoke come out. The battery has been removed now, but there's still a small ...
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2answers
94 views

Laptop fried from spark while connected via USB to a battery system

EDIT 10/11 9:40am Central: I learned from my partner on this project I got the order of events wrong. I have edited the post accordingly. I am working on some custom electrical hardware for ...
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0answers
41 views

Does replacing Li-ion accumulator with a pair of good quality AAA NiMH makes light shoes safer?

I bought my daughter a pair of light shoes (LED). Fortunately they broke down after 2 days and she's not wearing them anymore. After buying I realised that they probably have Li-ion accu inside. So I ...
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1answer
71 views

Safely housing a power supply

I'm building a 3-d printer, which will be driven by a smoothieboard. This needs a 24V power supply. I've bought the one shown below: What I don't know is how to house this safely. I think there's ...
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0answers
34 views

Reference material for mains-interfacing circuit safety

I've designed a simple switch/timer circuit for the following environment: Residential installation for North America (technically only for Canada) Single-phase 120Vac Current of switched output ...
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1answer
113 views

100V “rated” wire on 220V supply [on hold]

I am genuinely sorry for posting such a basic, basic, basic question. Moving to Thailand (220V) from Japan (100V). You cannot buy an extension cord in Thailand that is flush to the wall. Here in ...
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2answers
68 views

What is the purpose of galvanic isolation?

Is it correct to say that the primary reason to have galvanic isolation (ensuring minimum clearance and creepage distance for required voltage of power circuit between HV and LV) between the HV power ...
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1answer
43 views

Safety Relay Circuit

I am looking for a way to add a relay-based safety feature to my BLDC controller. In case of an emergency the user must be able to push an e-stop (probably consisting of an NC contacts) completely ...
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0answers
42 views

Battery Type Selection (Safety)

For my current project, I'm searching for the best battery type to use. The battery will be placed near the sensitive skin and hard (or even impossible) to remove fast in case of a failure. If it is a ...
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2answers
119 views

Protecting yourself with latex gloves

Would wearing white latex gloves(doctor gloves) protects you from getting shocked when repairing electronics? And is there a reason why you seldom see anyone wearing gloves when dealing with ...
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3answers
3k views

How could using an ungrounded appliance with a grounded extension cord be a fire hazard?

My local fire department, @Barrie_Fire, recently tweeted (then subsequently deleted) this: Don’t even THINK about using a 2-prong plug in a 3-hole slot! Use only the required number of slots in ...
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2answers
310 views

How to rinse container used for ferric chloride etching?

From what I have gathered online, after etching one stores the "used" ferric chloride (more specifically FeCl2 and CuCl) in some container which can then be taken to a waste disposal facility. What ...
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2answers
204 views

Safety design on mains detector

I've designed a simple mains detector which I have drawn below. The theory of operation is pretty simple. A capacitor is used to reduce the current so that my optocoupler can operate (represented by ...
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1answer
37 views

Is it appropriate to use a 300V RMS CAT I rated oscilloscope to measure 230V RMS of a power inverter?

Yesterday I decided to look at the waveform of my portable power inverter. The inverter specs are the following: Input: 12 V DC Output: 230 V RMS Rated power: 300 W I powered my inverter from a ...
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0answers
64 views

Does a lead/tin solder without rosin core release fume while soldering?

Many people address concerns regarding one possibly breathing toxic lead vapour from lead/tin solder wire by saying that the fume is from the flux in the solder wire, and not from the lead vaporising. ...
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0answers
74 views

Out of limit Touch Up current - Servicing PE

My device may not be connected to PE during normal operation, but does require 230VAC mains input. I know I have to take the touch up current of any Y-caps into consideration when developing my ...
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2answers
42 views

How Could I Implement a Fusable Safety Switch

I am looking to design a low-level safety override. This override can be represented as a three terminal device that is electrically a switch. simulate this circuit – Schematic created using ...
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4answers
459 views

Can a short circuit in the output of a transformer be dangerous?

Assume that I have a 220 to 12 volts transformer with a nominal output current of 3 A (marked "12 V 3 A"). Now what does happen if I connect the two output wires to each other or to a load with very ...
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1answer
108 views

earthing conductor

I'm studying the subject Electrical Safety in Engineering and a special term really drew my attention. When I tried to google it, no any option was suggested but Protective conductors. In the ...
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0answers
68 views

What is the definition of hull voltage?

I'm studying the subject Electrical Safety in Engineering and a special term really drew my attention. When I tried to google it, no any option was suggested but hull protection. In the presentation ...
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1answer
42 views

Safe solenoid driver: can I use a slow blow fuse?

I'm building a device that uses a microcontroller to control 15 solenoids via a preexisting multichannel DC solid state relay board. When all is working as intended, at most one solenoid will be ...
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1answer
64 views

10 Lamps setup 220v ac, would it be safe?

I am not an electrical engineering or anything, I am just a curious person trying things at my home for fun. I want to setup a lamp system for my sister's mirror where I would need to use 10 lamps ...
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1answer
37 views

Designing a 2S Li-ion charger with 5V 2A input

I'm interested in designing a few similar charging circuits based on the specs of the title which is getting a charging for 2 cells in series(or more) from a 5V input. Now my question is: Assuming I ...
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1answer
29 views

Long vs Short Earth Connection for Single Phase Motor vs 3 Phase Motor Frame

What is the correct way of grounding single phase motor frame if I have to choose between two options: (1) Short to earth connection: from the frame to nearest grounding rod. See below the schematic....
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1answer
555 views

What temperatures do resistors burn at?

I wanted to make a mini 12V heating element using 12 2 ohm resistors in series. What temperature will it be safe to heat it up to ? It is housed in acrylic housing which starts to melt at around 600 C
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2answers
70 views

What would be the safest method to power a laptop (IdeaPad 510 15isk) from a 14.8v battery pack?

Looking at my existing power jack and measuring it crudely with a cm ruler it looks like 3mm diameter x 1 cm length. The laptop bottom and charging adapter both say 20v @ 3.25 A max. What would be ...
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2answers
48 views

Questions about earth grounding enclosures

A text mentions about the importance of connecting the earth wire to an instrument case/enclosure as follows: Instruments with ungrounded cases can become lethal devices in the event of ...
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1answer
39 views

Wearable transceiver safety considerations

I am implementing a wearable band that will likely be fitted with a Zigbee or Bluetooth transceiver and worn on the wrist. However, I have seen many articles and datasheets specifying a distance of at ...
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1answer
49 views

ElectroVehicle batteries: safety issues

For a EV battery recycling project I am going to play with EV batteries. I will read out parameters from them (element configuration, charge, etc). I will NEVER try to recharge nor dismantle them: ...
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2answers
70 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 ...
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2answers
71 views

Question on Use of Y2 Saftey Capacitor in AA5 Style Tube Radio

In a radio I am restoring, there is a 0.1 uF capacitor between B- and chassis, designated as C12. My thought process is that if this capacitor were to fail, I would not want B- shorted to chassis as ...
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2answers
69 views

What to look for in an isolation transformer?

What do you want from an (isolation) transformer besides it having the minimum voltage/current/power(/frequency?) specs that the to be isolated device needs? Does it matter whether the transformer is ...
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2answers
67 views

Is it a safety issue to only bring the hot wire onto a board for mains switching?

I have a DC board that will be controlling my system. As part of my system, I need to toggle an AC motor on and off. At the moment, I have the hot wire off of my mains connection going into a terminal ...
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1answer
50 views

AC Line Testers

We've all seen AC line testers, with three lamps that diagnose the wiring of an electrical outlet (well at least in Canada/US). I'm (somewhat) used to the type that use neon bulbs, so I have two ...
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4answers
216 views

Does this appliance break UK safety laws?

Good evening. I recently purchased this active suction SMD pick-up tool from AliExpress: When it arrived, it seemed to work fine. However, when I opened it up (to investigate the feasibility of ...
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0answers
41 views

Regenerative/Dynamic Brake test set up for a BLDC Motor

As all you know that BLDC motor also operates in regenerative mode during deceleratrion and in such case the current flows back to the supply. Here I am using power resistor to dissipate the extra ...
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5answers
1k views

Safety of designing / using a plug that connects between two different wall outlets for increased voltage?

In North America we use 120V wall outlets, but sometimes 240V is needed for an application. Usually in a residential house in order to reduce load on the circuits they either run two different phases ...
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2answers
86 views

Safety of Using USB Charger [closed]

I am looking at getting a 3 port USB wall charger, to save having so many individual ones plugged in. A lot that I've seen offer Qualcomm FastCharge, and other similar things, which are around 2.4A, ...
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7answers
5k views

What is a reasonable way to connect small wires?

These wires will carry up to 1.5A at 5V outdoors in clear weather. Would it be reasonable to connect them by simply taping them together with electrical tape? I'm new to electronics outside of ...
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1answer
162 views

Connect two different sources with two Digital Ouptuts using an Adam 4055

I would like to operate an Adam 4055 module to control two different applications having their own power supply. Adam 4055 is Digital Input/Output control module over RS-485, I use only the DO part ...
51
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13answers
10k views

What kind of components in a computer power supply can explode loudly?

Today I heard a loud bang that tripped the circuit breaker in my server room. It must have been really loud because I could hear it 2 rooms away through 2 heavy doors and it was like a firecracker ...
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0answers
23 views

Symmetrical power supply: Rail fuses useful or dangerous?

I'm designing/testing power amp stuff with symmetrical power supplies (43V-0-43V). In the next future I'm planning to control all safety/healthy stuff (like over current / over voltage / temperature ...
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1answer
68 views

Wiring up ATX PSU to power (several) 12V LED strips

(In advance, please pardon my ignorance; I'm still learning) TL;RD. I want to power N number of 12V LED strips using a PC ATX PSU. Is it safe & what bits do I need to add to make it function as ...
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0answers
29 views

Intrinsically Safe Li-Pol batteries to 60079 standards

I have recently been looking at SAFT batteries and they have a range of Li-Ion batteries, such as the MP-144350. One advantage quoted is "High level of safety, compatible in potentially explosive ...
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1answer
44 views

Confusion with interpreting a functional safety diagram of a motor driver

I have a problem with interpreting the functional safety diagram of a servo motor driver. It has a long manual here but I will present the parts I'm stuck at. The minimum basic requirement for safety ...
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1answer
58 views

Safety for 48v leds in water

I'm builing a 48v DC LED system to be used inside a fountain in a public space. I'm using a 48DC 30A switching power supply. What should I do to make it safe in case any conductor gets exposed to the ...
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1answer
58 views

Oscilloscope differential measurement for battery powered circuit using single probe

I want to measure the voltage across a resistor in my circuit. The circuit is battery powered. I don't want to use the two probe method and calculate A-B to get the results. Can I use one probe to ...
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2answers
153 views

Earthing Bracelet safety

I have a family friend which likes to sleep with a direct connection to earth. This question is purely to do with safety, nothing to do with what you or I or anyone for that matter believes about this ...
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2answers
115 views

Aluminum Electrolytic Capacitor with small dent still usable?

I have three 10000µF 75V Aluminum Electrolytic Capacitors. The aluminum can has a very shallow dent. Would you think this is still safe to use them? I have three of them, and they are expensive