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.

81 questions with no upvoted or accepted answers
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468 views

Designing single fault safety into class I device

I'm trying to wrap my head around safety standards for electrical equipment. My device is medical, so for me section 8 of IEC60601-1 is what really matters to me, but it's kind of my understanding ...
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1answer
78 views

IATA battery rules

Following IATA guidelines two threshold limits are indicated: 20Wh for cells and 100Wh for multi-cell batteries. Question: Should I apply 20Wh limit also for cells in multi-cell batteries? Example: ...
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1answer
72 views

Shipping & Handling Electronics & Electro-mechanical parts

What are common packaging(Shipping & Handling) guidelines (specs/stds) for Electronics & Electro-mechanical parts? Currently, working on adding onto our current generic guidelines for ...
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0answers
19 views

Standards Compliant High DC Load Safety Interlock System

I have a single AC-DC supply (42V @ 600W) which supplies three motive loads. Each motive load is physically separate and has its own cover which prevents the operator from gaining access to the moving ...
2
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1answer
51 views

UL certification and laser tag equipment

We are a 32+-year-old laser tag equipment company. We purchase parts overseas and assemble them in the US and have hundreds of installations all over the world. We have been told by 1 location that ...
2
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1answer
72 views

Is it safe to use individual conductors removed from a multi-conductor cable?

I am working on setting up a research lab at a university as a graduate research assistant. We're working on power electronics in a three-phase environment, which means we'll be using at most five ...
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0answers
36 views

Is C-SAM test needed for new baking oven for IC?

I bought a conventional oven for baking ICs. Do i need to perform C-SAM test on the units after baking? I think units will not be affected if you will use the required baking temperature and time ...
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1answer
29 views

Electrostatic arc safety

I'm experimenting with early electrostatic devices, and I'm measuring spark gap length to determine voltages generated. How dangerous is it to observe these arcs with the naked eye? Should I wear ...
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0answers
33 views

Is putting a board inside an anti-static enclosure enough to make it Ex ib ready?

A year ago, we made a handheld PDA based on RPi0 for a client. Now they have asked us to certificate it as Ex ib IIC T4. Here is the PDA's spec: RPi0 as processing board 4.3" capcitive LCD A ...
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1answer
45 views

Constant current driver and undervoltage protection for lipos

I'm searching for a way to drive a couple LEDs with a single-cell LiPo battery, such that the LEDs will be cut off completely when the LiPo voltage drops below, say, 3.3V. PCB space, component count ...
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0answers
95 views

What is the benefit of a male output connector on a powersupply?

I saw several power supplies which use a male output connector. For example the Meanwell OWA 90E series uses a XLR 4P or ...
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1answer
83 views

Safe to turn off power by removing a plug fuse indefinitely?

I'm trying to turn off the power for my dining room light and as I live in an old apartment, my fuse box only has plug fuses (and a main fuse you pull out). My plan is to cap the AC wires in the ...
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158 views

Will my 555 timer circuit work the way I want it to?

Essentially, I am trying to implement a safety system for another project of mine. I am running a very high current through a rather large solenoid and want to ensure that a failure in its control ...
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0answers
60 views

Heel strap vs wrist strap around ankle

I am a novice to electronics, and I am currently building a home workstation. In this question on ESD chairs, the user Sparky256 said the following in his answer: If you are wearing BOTH a wrist and ...
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0answers
44 views

How safe are Isolation Amplifiers compared to Voltage Transformer

I was searching for a miniature transformer for my 240V AC voltage measurement circuit and a kind individual recommended me a pecular IC. The IC is a Differential Isolated Amplifier AMC1100. And it ...
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0answers
69 views

How can I protect my amplifier, MCU, and laptop from damage in my application circuit?

I am trying to integrate a few devices for a laser stabilization system. I have a tentative circuit diagram that I'm asking for more expert guidance in implementing. I am using an MX200 from ...
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1answer
98 views

Repairing burned PCB traces for 220V. Is it safe if I don't know why they burned?

I'm trying to fix the cooker hood of my kitchen and I found that the problem is in the controller. The PCB has two burned traces, respectively to the electric source of 220V (neutral and phase... ...
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0answers
36 views

Heatsink Crossing Primary and Secondary Sides in Switched-Mode Power Supply

I've taken apart a non-oem laptop power supply. There is clearance on the board between primary and secondary. However, they've placed a single heatsink across the board for the primary and secondary ...
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66 views

Bonding Electric Vehicles: Which System to Implement (safety)?

I am currently working on building an autonomous electrical vehicle and would like some input on which bonding system would be safest and most practical. The system battery is 48V (dc) and which feeds ...
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95 views

How to know what is the safety standard to apply to a PCB design?

I want to design a PCB with some points at some KV during certain times, less than 10KV and no more than 30mA of current. After dealing with concepts and getting the main idea about my circuit needs, ...
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48 views

Electrical Safety Guideline for LVD Compliance

We are making a product -a warning light- with 220V rated voltage. The product has a non isolated offline buck regulator. The 220V part can be accessed without the use of a special tool (there is a "...
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0answers
32 views

Standard LiPo battery packs & product liability

I'm designing a high-power portable product that I would like to eventually bring to market. I need to use LiPo battery packs in order to achieve sufficient energy density, but I do not think I will ...
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2answers
1k views

Definition of Field Wiring Terminals as in UL 499

I'm wondering if anyone can tell me where I can find the definition for "field wiring terminals" as referenced in UL 499 "Standard for Safety Electric Heating Appliances" table 27.1 "Minimum ...
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0answers
97 views

Is this safe? Wiring for power relay jqc-3fc(t73)dc5v

I have an ac relay jqc-3fc(t73)dc5v that I am trying to use with a atmega and drive with 5v. Is the wiring as shown in the picture a good idea? Considering that ac and DC need to be very close ...
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0answers
60 views

Why are contactor coils connected to two different safety relay outputs?

When looking through a manual for a safety relay, I began to wonder why the coils of the load contactors (K3 and K4 on pages 14-15) are always connected to two different NO contacts of the safety ...
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132 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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445 views

Earth leakage from isolated power supply

I have recently put together a DIY bench power supply using a DPS5015 from Rui Deng and an old laptop power supply. Everything seems to be working fine except for a small amount of current leaking to ...
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1answer
78 views

Is there any risk in leaving a Li-ion connected to a solar panel with only step-down converter?

I have a 18V solar panel which is connected to a step-down buck converter, which drops the voltage from 18V to 3.5V. When clouds block the sun, the voltage drops to less than 3.1V. I have added a ...
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2answers
209 views

Is this a safe way to add extra current control for a DIY tDCs device?

I have put together the well known DIY tDCs-device Inthinkerator MK1, and wanted to add an extra safety feature, but I dont know if this is the correct way to do it. The original design is without the ...
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0answers
3k views

Calculate RC snubber for 240v ac coil relay

In a project I use several 12v dc coil electromechanical relays. I use diodes in parallel to the coil protect them from flyback. I also have one relay with an 240v ac coil. I have learned that I ...
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120 views

0.8mm PCB for a PSU circuit

I am working on a PSU that converts 230 VAC to 12Vdc (0.1 A). The board has the necessary clearance and creepage distances. Would it cause any safety issue (IEC60950) if the 0.8 mm (or 1.2 mm) thick ...
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171 views

Safety/Quality issues by modding PC PSU to be floating.

Since I don't have enough money at the moment to purchase a good bench power supply, I want to 'mod' a PSU. In the first instance not by opening the PSU, but just by making an adapter that also puts a ...
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1answer
125 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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1answer
178 views

lithium coin cells, safe to completely cover? lightweight method to protect from the environment

I am trying to make equipment to measure temperature in small mammals, probably attached to a neck collar. The collar needs to be very lightweight (e.g. <3g total) so I am planning to use a ...
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29 views

One double pole relay or two single pole relays for live and neutral?

I'm designing a PCB that will control AC 240V electric tools. For now I decided to use a single double pole relay to switch live and neutral lines. Is it also safe to use two separate single pole ...
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1answer
43 views

How much clearance do I need between floating ground and earth referenced ground?

I have two circuits where one side is earth reference and another floating. The floating circuit is isolated by a transformer and talk to the earth reference circuit via opto-coupler. During final ...
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1answer
53 views

Temperature of Power Driver ICs

I'm using TI DRV595 power driver in an application requiring several amperes of current. My observation using thermal camera has been that at 3.5 A the driver IC core reaches temperatures around 90 ...
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25 views

Lithium Ion Battery - Testing & Self Discharge

It is suggested and commonly understood that if Li-ion batteries drop below a certain threshold that we consider the cell(s) unstable and untrustworthy with a loss in cell capacity and that increased ...
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55 views

Concentrated Ozone Treatments for COVID-19 Sterilization: What levels and duration are safe for consumer electronics?

Operating a critical IT service for necessary businesses brings some risks at this time that need to be mitigated. I have some powerful ozone equipment used to sanitize / sterilize rental property and ...
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73 views

Relay contact side protection

Do we need any protection on the contact side of the relay (Ex: form C 240V 3A) if the contact side is not powered by the circuit. if we have to protect, then how(Please provide an example). Also, ...
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58 views

how to proteus simulation inrush current

i've a reverse polarity protection , i want to check inrush current simulation , but i don't know how . i read this , but i tried but doesnt work How to plot voltage vs current graph on Proteus ...
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0answers
78 views

Adjustable voltage doubler circuit across resistive load…doable?

Disclaimer: what I am proposing is dangerous, and I know that. I would discourage anyone, regardless of expertise from undertaking such a pointless risk to their health and home. After my recent (mis)...
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32 views

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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42 views

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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29 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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2answers
39 views

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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49 views

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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30 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
40 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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2answers
417 views

Ws2812b circuit safety with 5V 12A

i am making a arduino project using 5v ws2812b 300leds/meter. Its going to be a motion activated led strip that runs along the side of the stairs. I will be using 3.5m of the led strip so 210leds at ...