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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IEC 60950-1 Test Report For Power Supply

The current power supply that we have from our vendor has a straight DC connector. That's the way it was tested for 60950-1. If we change the connector to a right-angled DC connector, is the IEC 60950-...
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74 views

Does this circcuit pose a safety risk that could be avoided?

I was looking over the circuit design for OpenEVSE. I was specifically interested in the GFCI portion of the circuit: This circuit measures the current difference between Line and Neutral on a 120/...
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Taping down cord with duct tape fire hazard?

Curious as to if taping down a cord is a fire hazard. Some cords have very thick insulation and rubber so I do not see how it would be the case. I will try to find the article and update the post if ...
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What makes mains voltage safe in homes?

When I started learning about electrical engineering, one of the most important safety guidelines that I learned was that voltages over 36V can be dangerous. As my circuits professor put it, 120VAC ...
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1answer
63 views

Why does the high capacitance of a metal oxide varistor affect sensors and signal sensitivity?

I want to know why the high capacitance of metal oxide varistors affects sensors, signal sensitivity. How does capacitance affect sensitivity ? If we add a low capacitor in series will the total ...
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10answers
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Is DC 5V and 2A dangerous to me? [duplicate]

I am new to electronics so please forgive me. I am looking at powering a WS2812B RGB strip. Specifically 144 LEDs/ meter. After doing some research I found that 200mA is lethal and can kill. Now, of ...
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Can we use tvs and mov together for thruster?

I want to know if we can use both tvs and mov varistor together ? What will be good for thrusters ? And placement between esc and thruster or before esc? Update: system voltage is power supply ...
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23 views

p mosfet calculations reverse polarity for high power ( 48 V , 30 A )

i want to make reverse polarity protection for input 48 voltage , load 30 Ampere 2 dc buck converters. i was searching many solutions like diodes , but i wanna make it with p fet , so i came across ...
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41 views

Reverse Polarity Protection relay calculation

i want to make reverse polarity protection without voltage drop ,i was searching and i found this https://www.edn.com/design/analog/4368527/Simple-reverse-polarity-protection-circuit-has-no-voltage-...
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1answer
47 views

What 'rated voltage' means in VDE certificates?

In a VDE certificate for a component (plugin green terminal blocks), a column gives the "Rated voltage(s) / V" with a value of "400" without specification wether it's VAC or VDC. Does this mean that ...
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115 views

BLDC/BLAC controller motor voltage reverse protection

I am currently designing a BLDC controller and keep running into a power safety issue: I have added a smart diode reverse protection controller to my design with its transistor between the fuse and ...
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2answers
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Can I use pre-regulated PoE power safely/within specifications?

I'm attempting to design a PoE PD for fairly high-power applications; chiefly, powering/driving stepper motors. Currently, both motors and drivers run at 24V and will consume about 30W per PD. At that ...
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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 ...
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Can I charge a NiCd battery with a NiMH charger?

I have an old NiCd RC battery pack. It was not used for at least ten years but when I tried to charge it with the old charger I was suprised to see it still had some capacity. Now I just went and ...
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Which implementation of a safety stop is more accurate?

I recently got into an argument with a friend over what the correct implementation of a safety switch for a motor with a spark gap is. So for intents and purposes, here is the simplified schematic ...
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How to safely test a Lithium Battery Management System board

I'd like to design a Battery Managements System board (based on TI bq40z50-R2) for my own small (2-4s) lithium battery pack, but I am still unsure how can I test it safely. I am worried that an error ...
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718 views

Is This “E-Power” Machine Dangeorus?

My mother is obsessed with new-age quackery, and has rented an "E-Power" machine, a device that appears to be a waveform generator connected to a belt that you wrap around your waist. I'm concerned ...
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IoT Certification Legality

I am developing an IoT product for a company. The product runs off of two alkaline batteries at a max of 3.2V. It is fully enclosed in a solid plastic case, with small panel openings for a switch and ...
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1k views

What is the maximum voltage of a Lithium Ion Battery

My question is about the maximum charge voltage of a Lithium-Ion cell. I have charged my battery pack with 8.4V (the maximum voltage). The pack is a Samsung ICR18650-26F. The pack has a smart ...
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24 views

Using a TP4056 with a 08570 Battery

Will a TP4056 (the ones with mini USB and no battery protection) charge a 08570 battery safely? From what I can tell the battery does have built in battery protection but I cannot find much ...
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1answer
36 views

Designing an over discharge lithium ion protection circuit

I am trying to build a portable RGB LED display that runs off a Lithium Ion battery. After a few days of research, I understand the importance of using a dedicated IC to handle charging the battery, ...
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1answer
54 views

Current flow in trailing edge dimmer

I was trying to learn something about dimmers for light bulbs. After some reading, I found that most trailing edge dimmers contain some variant of this: Found for example in this diy-project or this ...
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2answers
680 views

How safe is using non-RoHS parts?

I was wondering the safety of using non-RoHS parts for hobby projects. I already use non-leaded solder, but some of the parts I have are not RoHS compliant. How much would I, and my family, be exposed ...
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2answers
78 views

Abusing EPS connector to power LED's?

I'm working on the wiring harness for a PC build that's going to include a bunch of (5050) LED strip lights. The strips will be wired to fan connectors (more details at end). For testing, I've been ...
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1answer
56 views

Safety Rated Sensors [closed]

I am trying to find a safety sensor for a machine. The sensor should be safety rated as it will be used to detect if a cover is removed and will shut down robotics and uvc bulbs which is harmful to ...
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139 views

Back branches in code

While reading this file on software hazards this slide says: "No Back Branch in the Code" I wonder what does it mean? Normally when we write code in C-language then we don't actually do branching ...
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1answer
126 views

Safety precautions when developing and testing mains voltage devices [closed]

Specifically, I am planning to design and build an energy meter to measure power drawn from mains - 120V 60Hz. What are the risks associated with developing and testing this device and how to minimize/...
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1answer
36 views

Protection circuitry for AC/DC converter

I'm using the RAC02-GB (Datasheet) as an AC/DC converter and I'm confused about the protection circuit they included in the datasheet: I want to make sure the AC/DC converter has the proper external ...
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1answer
78 views

Oscilloscope and Electrical Safety

I was reading an article in a magazine in which the following sentence is written about a circuit that generates a certain waveform on a load R (in which one of its terminals is connected to the earth ...
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4answers
206 views

Safety: Can I harm myself using an AC, 9V 500mA power supply for experiments?

I'm about to embark on my first electronics project and would like to check off a safety question: I want to build a bicycle hub dynamo -> USB charger based on these instructions. It is basically a ...
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2answers
112 views

Can an electrified wire ever be safe against bare skin?

This could sound ridiculous to someone with an ounce of experience, but I'm just getting started, so here we go ;) Full question is 3 parts... First, what is the lowest amperage needed to light an ...
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6answers
6k views

Why aren't starter circuits protected?

In most cars and trucks, a thick cable connects the battery directly to the starter (solenoid). Why don't these circuits have have any kind of overcurrent protection? It is an accepted practice ...
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1answer
27 views

What safety regulations do I need to follow for wiring of a decorative lamp utilizing a fluorescent tube with g10q fitting?

I'm building a cast concrete decorative lamp. It will use an exposed circular fluorescent bulb, which attaches to a g10q lampholder. I understand I will need to wire it up to a ballast and starter, ...
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711 views

How safety capacitor replaces optocoupler

I see some phone chargers using safety capacitor (after some research I found its safety capacitor)But not optocoupler to isolate in and out . How safety capacitors replace the optocoupler
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2answers
133 views

How does electrocution (fatal) happen? [closed]

I'm trying to make my workshop safer but I can't understand how electrocution happens. For example, one hand is touching to live wire and neutral wire is not touched. If I know right, current flows ...
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2answers
111 views

Is this the correct way to wire my transformer?

I am building a 12 V dual power supply. Since this is the first time I will be using mains (230 V). I would like to make sure that I am not going to burn down my house. The transformer I want to use ...
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5answers
243 views

How are electric water heating elements isolated?

From what I've seen and understood, electric water heating elements are usually copper tubes/pipes with electricity running through them to heat up the surrounding water. I'm not sure if the ...
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3answers
83 views

Safety and isolation transformers

What safety measures can be taken when using a 1:1 isolation transformer in order to avoid electric shock even if someone touches both ends of the secondary? Would an insulation monitoring device be ...
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2answers
2k 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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1answer
82 views

Is there anything besides power factor that determines the max CFL that can be used in a socket compared to the max incandescent for that socket?

When shopping for lamps recently, I've noticed that the sticker on the socket says something along the lines of "To reduce risk of fire, use maximum 60 watt incandescent or 13 watt compact fluorescent....
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9answers
373k views

How much voltage/current is “dangerous”?

Related: Safe current/voltage limit for human contact? From what I've heard: 110 V (or 220 V; household voltage pretty much) is dangerous (i.e. can kill you) I think there's consensus on this, ...
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1answer
51 views

AC power supply safety

I am planning on building a vintage tube radio from schematics. Part of the radio will include its (multi-voltage output) power supply, with an AC power cord, AC switch, and transformers. Are they ...
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2answers
757 views

Is a capacitive touch screen safe to use?

I was reading about capacitive touch screens. I understood that your hand picks some current flowing on screen. That sounds alarming. Is it safe to use a capacitive touch screen, since it picks small ...
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1answer
1k 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 ...
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3answers
729 views

Is a separate safety earth connection necessary when using an earthed power entry module?

Testing the Schaffner FN1394-10-05-11 power entry module with a multimeter shows continuity between the ground pin and the body of the module. Consequently, when the module is fitted into an aluminum ...
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1answer
112 views

Are there more (mains) electrical safety incidents in the United States compared to the UK? [closed]

Forgive me if this question isn't exactly "on topic" for this site -- it's a bit meta. I am an academic in the UK, and I occasionally design electrical devices that plug into "the mains" in one ...
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1answer
57 views

How to measure laser class of LIDAR

I just bought a LIDAR with the intention of building an indoors robot that uses it to navigate rooms in my apartment. The manufacturer website states: Low power infrared transmitter conforms to ...
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3answers
6k views

Maximum Current Draw on Vin Pin

I don't want to damage the pins on my Arduino Uno, and I'm especially cautious of drawing too much current. I'm experimenting with a small servo motor (similar to this one), and have connected the ...
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3answers
67 views

Electrical Standards - Earth Wire at Low Voltages?

I got a question about safety standards: I'm designing a consumer device and I'm not sure whether I need an earth wire. I have an AC-DC converter plug that outputs 5 V and up-to a maximum of 1 A ...
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1answer
75 views

How to power up a project with 3 devices, between 0 and 12 volts

I'm working on a project which involves a DC heating element, a computer fan and an Arduino/ESP8266. I'd like to use one power supply for those devices..... The requirements: The heater needs a ...

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