Questions tagged [fuses]

Questions regarding physical fuses. Fuses are a safety device consisting of a strip of wire that melts and breaks an electric circuit if the current exceeds a safe level. PPTC, PTC, and Polyfuse questions should use the Polyfuse Tag. Please keep in mind that repair questions are typically closed if not within the scope of the Site and FAQ.

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External RC oscillator fuse programmed instead of external crystal fuse

Is there anyway to revive an Atmega8A? avrdude says avrdude: error: program enable: target doesn't answer. 1 ever since I ...
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Why does my oven trip the kitchen circuit fuse? [migrated]

After a recent refurb where some of the electrics were also changed (including consumer unit and a full rewire), I noticed that when using the oven it would sometimes trip the kitchen fuse. Where ...
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Need Help Identifying - Pentair pool automation motherboard

Hoping someone can help me identify the component in this picture. This is a Pentair pool automation motherboard - model number 520073. The top part of the photo shows what I believe is a capacitor ...
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How to identify which live wire go with which neutral wire? [migrated]

Context I have an old electrical panel, with fuses. I want to replace it with a new electrical panel. In this panel there some problems, no color were respected, and the live wire and the neutral ...
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2 votes
1 answer
50 views

How to safely protect input sensing AC Line Voltage

I'd like to detect the presence of AC line-level voltages in my PCB project, and I'd like to follow best-practice for doing this. I'm a controls engineer so I'm happy with dealing with mains with ...
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0 votes
1 answer
29 views

Can I replace a P labeled SMD fuse with a K labeled one?

I am fixing an "old" laptop and I needed to replace a broken screen. While disconecting and reconnecting the ribbon cable, I probably shorted something. Now the back light on both the ...
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3 votes
3 answers
2k views

Can this resistor be replaced by a wire or fuse?

My power supply got broken. Upon further inspection, I found out that the high power resistor (15 ohm, 10 W) was broken. Unfortunately, I can't purchase such a resistor (with the same specifications, ...
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1 answer
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Have I been poisoned by lead dust from my blown fuse

just wondering if I've poisoned myself. I was doing something silly and the 10A fuse exploded in my multimeter with the glass cylinder and alloy dust shattering and splattering making a mess on the ...
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1 answer
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OVP with crowbar + TVS?

I'm looking to design an over voltage protection (for > 13-14V situations) on the input of a power supply (the PS is taking input from a 12V vehicle). I was considering only using a crowbar circuit ...
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1 answer
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Safety check - Is this Amazon PV combiner box labeled wrong? 15A Vs 32A - 500V vs 1000V

I'm currently working on a solar circuit. I wanted to protect my internal systems from my panels in the event of a surge. I purchased a PV combiner box from Amazon - link to product. It claims to be a ...
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1 answer
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Trying to fix a possible non-removable permanent fuse

I'm having some issues with a PCB in an alarm unit. I think the unit shorted. I'm now trying to identify the broken component to replace it. The board is mains powered, but also has a battery - ...
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4 votes
2 answers
199 views

DC power supply and fuses

I came across a DCDC converter JCK3012D15, that takes a 9-18VDC in and gives out +-15V @ 1A (pretty handy). I have some questions: What is the advantage of using a power MOSFET at the input over ...
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0 votes
1 answer
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Can an extender with USB ports be wired direct to the mains?

I have an extension lead that has been wired directly into the mains (there is no space behind a cupboard to plug it into the wall socket that was there). I think this is the same situation as adding ...
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4 votes
4 answers
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Why do Americans use fuses and not differentials and breakers like Europeans do?

I recently moved to North America, and I was wondering why the houses here seem to be protected by fuses rather than breakers and differential switches like we have in France for example. It would ...
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0 votes
2 answers
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Can a lower gauge jumper be connected to a high amperage circuit as long as it is going to an appropriate sized breaker?

The 14 AWG wire is connected to an appropriate sized circuit breaker to prevent that run of wire from drawing too many amps; however, my concerns would be that the 2/0 cable being in such close ...
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4 votes
1 answer
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Breaking capacity for fuses at mains inlet

Is there any official guidance as to what the breaking capacity should be for a mains inlet fuse? Assuming the appliance is intended to be fed from a normal domestic socket. I understand that in an ...
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1 answer
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I'm trying to replace a component on a circuit board. Is this a fuse?

This smd component has shorted. I'm assuming it is a fuse, but I don't understand what the 4 over the underscore means, if it is even a "4". Does somebody know what this component is and how ...
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1 vote
3 answers
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Why are Fuses on space heaters necessary?

Why does a space heater (electric fan heater for home use) have a fuse? Isn't the house itself connected via a circuit breaker? Wouldn't that stop potential safety issues? PS: First post on here :)
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2 answers
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Can I use a 315 mA slow blow fuse instead of a 375 mA slow blow?

This is my first post here and I am not an electronics engineer (just a simple guitar player) who would appreciate some advice. I have a relatively old (no longer produced) valve guitar amp which has ...
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How do you install a thermal fuse in a hairdryer?

Is it possible to manually wrap the thermal fuse's pins around the 'grommets' as shown in the picture? The arrows point to the two grommets, with the thermal fuse in the question across the top.
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Correct Fuse Sizing

How can I correctly select the size of the fuse on the primary side of a transformer based on a transformer? The regulators in this circuit are an LM317 and an LM337 which draw a maximum of 1.5 amps, ...
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1 vote
2 answers
94 views

Resettable fuse hold current and trip current

When choosing a suitable current rating for a resettable fuse do we usually look at the hold current or trip current of the fuse? From what I understand, the fuse will not trip when current reaches ...
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Does an eFuse exist that latches off immediately (and does not reactivate) in case of a short-circuit?

I've just discovered eFuses (from Texas Instruments + Toshiba + STMicro). In case of a short-circuit on the output, MOS can be disabled in 150-500 ns by detecting a surge of current (called "fast-...
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2 votes
1 answer
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What does "FB" for a fuse mean?

I have a blown GE 250v 20a FB WB27X27316 that I need to replace. Unfortunately, GE doesn't have them in stock for another 3 months. I want to replace it with another off-the-shelf fuse, but I don't ...
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8 votes
9 answers
1k views

Do I misunderstand fuses?

A statement that I often read here goes: "Fuses protect the wire, not the load." However, in basically all cases I use fuses, I think they are there to protect the load - I.e. the device on ...
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1 vote
1 answer
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How should fuse selection be made in discrete-time alternating current?

In my circuit,I have a resistive load(Lamp).(Rlamp=1 ohm).At the ends of the lamp is voltage V(t) in the picture.In the picture, there is the first 12 seconds of the signal.But you may think that ...
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3 votes
2 answers
349 views

What kind of weird current protection "circuit" is this?

After seeing this schematic in this answer (from @VictorTito ... and others) in this post ... I was curious to try it ... Added one resistor and I simulated this (?) (DC Analysis) ... Meanwhile, by @...
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1 answer
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Are T4A and T4AL the same kind of fuse?

A power supply for some equipment I have blew its fuse. The fuse holding is labeled T4A 250v. When I look for replacements ...
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1 answer
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Need suggestions to replace fuse in broken coffee warmer [closed]

My coffee warmer suddenly stopped working after it did little sparky thing one day and I am trying to see if I can fix it. I opened the cover and tested all the capacitors and diodes and everything ...
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0 votes
2 answers
91 views

Selecting a fuse for a device that powers on at 48V @ 0.1 amps

I am passing current through an Ethernet cable in order to power on a device. Basically I am making use of the Blue and Brown cables: The device that I am powering uses 48 V DC and only uses 0.1 amps....
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SMPS power supply - fuse resistor calculation

I'm designing a TNY288-based SMPS. My transformer input inductance is 931μH. I'm using a 320V MOV and have a doubt about the fusible resistor calculation. The output load is 12W, the input capacitor ...
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2 votes
2 answers
42 views

Do circuit reclosers of substations respond to any fault on the low voltage side of distribution transformer?

As I don't have any practical experience in power distribution networks, I'm pretty confused about a few things. Typically a lot of transformers are connected to an 11KV distribution line ( 11KV ...
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1 vote
1 answer
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Does a resetable device like this exist for EV charging? [closed]

I am quite unfamiliar with wiring in residential houses so bear with me. I have an electric car that I can charge with 32A EVSE. My main house fuse is 32A. I am curious if there is a device that can ...
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1 vote
2 answers
49 views

Battery considerations for a mobile computer station

I'm a pharmacist, not someone in an electronics trade. I'm creating a prototype mobile workstation to be mounted to a medical cart. I have a 12V 2A micro-PC and 12V 4-5A monitor (both have DC inputs ...
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1 answer
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Protect high voltage little currents

Short question: Are there alternatives to very low currents fuses? I need something that breaks at about 6 mA. and I cannot find anything like that. Long question: I am trying to detect mains (230VAC) ...
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0 votes
2 answers
61 views

Why would a 32VDC fuse only work with 22VAC?

I am trying to find a 6-port version of this: https://czh-labs.com/products/czh-labs-din-rail-mount-ac-dc-532v-10-position-power-distribution-fuse-module-board-p0445 I found something close (https://...
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10 votes
10 answers
3k views

Why is the fuse connected to the live wire?

As far as I can understand the concept of AC, it does not matter which wire is live or neutral as this changes like 100 times per second (implying 50Hz) I believe. I read the fuse must be connected to ...
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2 votes
0 answers
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How do I destroy my multimeters?

During a task that involves current measurement in the mA and µA range, I managed to blow up the fuses of 3 DMMs. The DMMs were an old Voltcraft DMM from the 1990's, a PeakTech 2025 (similar to the ...
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1 vote
1 answer
177 views

What is a PED fuse?

I have a 1996 bus with some things that look like metal encased fuses connected to some wires in a battery box. They are marked as PED. Does anyone know what PED fuses are? Google hasn't been very ...
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0 votes
2 answers
74 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. ...
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6 votes
4 answers
2k views

Limiting 1000 µF capacitor inrush current to protect fuse and power source

I have a WS2812b (NeoPixel) strip controlled by ATmega and powered by 5 V 2 A cell-phone style charger (from Digi-Key). The strip itself is located about 1.3 m away from the power source and ...
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0 votes
0 answers
63 views

RTX2080 Super - Fuse blown on PCIE 12v

I bought a 2080Super (Palit Super X). It was a cheapy on eBay and after a little bit of poking around, I found a blown fuse on the PCIE power 12v. The card was absolutely dead, core didn't heat up etc ...
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0 votes
1 answer
45 views

Can an auto reset fuse and capacitor save my tracking device from surges while keeping it running?

I work with a few tracking devices and the newest model keeps popping. I've narrowed it down to possible short term current spikes in the trucks they are installed on. The device receives power from ...
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-1 votes
4 answers
184 views

Why does a fuse break before an LED?

Assuming the current passing is more than what both the fuse and the LED can handle, if electrons pass through the bulb first, would the fuse break first, or is it a matter of the LED requiring more ...
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0 votes
3 answers
303 views

Why multimeter 10A fuse blew when measuring voltage? [closed]

Trying to figure out what happened to not make the same mistake. I was measuring if electricity is on or off on wires and with usual V port (600 mA) it showed weirdly huge number - above 1000, where ...
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14 votes
2 answers
5k views

Suicidal ASUS power brick?

I was playing around disassembling an Asus laptop power brick (19V, 4.74A) and came across this strange arrangement in the circuit, where just after the bridge rectifier, there is a MOSFET (Q1, N ...
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1 vote
1 answer
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Parallel batteries - blown fuse detection

We have parallel 48V batteries connected with fuses as shown below: How can we detect a fuse being blown by a MCU connected with same common ground with a separate power supply? Edit 1: Note that ...
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1 vote
2 answers
89 views

Can a fuse (non-resettable) wear out over time?

If a given circuit (containing a fuse) operates perfectly and continuously, will there come a time when the fuse simply stops working due to age and wear (wear from passively passing current ...
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3 votes
3 answers
1k views

How do I protect the power supply from a short circuit inside a device?

I'm working on an electronics project which would be powered by a 12V power adapter. I'm worried that in a case of a short circuit inside the device I'm making, the adapter could catch fire. Every ...
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0 votes
1 answer
143 views

Taking Apart A Fuse Safely

I’m planning to make a Van De Graaf generator, and it requires using only the glass part from a fuse. Is it safe to remove the glass part from a fuse by heating it with soldering iron or match? I ...
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