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Questions tagged [circuit-breaker]

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1answer
57 views

Safety switch “breaking capacity” vs. voltage

In the context of safety switch rating (fuses, circuit breakers, etc.), the concept of breaking capacity refers to the maximum electric current which can be safely interrupted by a tripping safety ...
0
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1answer
69 views

Does a 5A Car Fuse Blows in a 12 Miliseconds Peak of 6A, in a 220v Circuit?

Thinking here in using a 5A fuse in a certain circuit, but it may reach 6A sometimes for a mather of 10 or 12 miliseconds only. That way, would this fuse blow or it would sustain and blow only in ...
0
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1answer
51 views

Flash in MCCB when switched off

Recently I switched off several molded case circuit breaker (MCCB) and saw a flash at the back of the breaker for an instant. This happened to all the MCCB on-site (around 14). The MCCB are all rated ...
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0answers
20 views

Can you trip a breaker from a different circuit? [migrated]

Background I had a wall outlet wired like the one below. I wanted to move it over about 4 feet, so I bought some electrical wire and used it to extend the existing wire. () As you can see, it was ...
0
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0answers
38 views

What do the white and green colours on the earth leakage CB denote?

I've come across two 4 pole earth leakage circuit breakers, one with the all green lever and another with white levers for phases and green for neutral. Is there any special meaning to this? I've ...
1
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2answers
109 views

Why arc only happens when circuit on load?

I'm preparing research about high voltage electric distribution for my university but I don't understand why the arc only happen when current is flowing. I made my internship in an electric ...
0
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0answers
32 views

Circuit breaker wiring: put source current on side marked with X or side with switch? [duplicate]

I am trying to wire an electrical panel in a standard manner. I have several automation devices that take 120 Vac power. In order to protect them, I have purchased a 2-pole circuit breaker, Phoenix ...
0
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0answers
47 views

Protection Devices in DC ciruits

I am putting together a design for a custom Electrical panel. The panel consists of mainly DC powered components (Sensors, Controllers). Components are to be mechanically positioned using a DIN rail. ...
0
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1answer
130 views

Switching Power Supply - Type of MCB for Inrush Current

it's regarding this PSU from Mean Well: https://www.meanwell.com/Upload/PDF/LRS-350/LRS-350-SPEC.PDF It has a 60A inrush current. My lighting circuit (1.5mm2 wiring) is tied to this PSU supplying ...
0
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1answer
52 views

Switching Power Supply - Inrush Current, Input Current, MCB

I am getting several PSUs (LRS-350-24) from Mean Well. Here's the specs: https://www.meanwell.com/Upload/PDF/LRS-350/LRS-350-SPEC.PDF 1) The input current is stated to be 3.4A/230VAC at 88%. 350W ...
0
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2answers
34 views

24V LED Strip Circuit - Switch, Breaker & Wiring Size Requirement

I am running a long LED strip (24V, 21 meter, 0.6A per meter, so technically 13A). The 24V PSU supplying power to the strips is to be connected to a switch that is rated 240V, 10A & 2400W. ...
0
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1answer
51 views

Tripping a circuit breaker when using a half wave rectifier

How does a half wave rectifier or phase control dimmer affect the triggering of a circuit breaker? For example, if a 20A resistive load was on a 15A breaker with a half wave rectifier. Now average RMS ...
0
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2answers
38 views

Both fuse and circuit breaker operated

Is there a reason that both a fuse and a circuit breaker would operate? From my understanding, the fuse should blow first and kill any current flowing through it leaving the breaker intact. So why ...
1
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0answers
35 views

Modeling the thermal part of the Time-current curve

G’ day, I am working on designing protection devices for my research work and I am struggling to model the thermal part for the low voltage circuit breakers based on IEC standards. Based on the ...
0
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1answer
54 views

MCB with electronic trigger-off [closed]

How can I design a system that gives the functionality of an MCB (overload protection, operates in an AC circuit) with an electronic trigger-off. So that once the device is in ON state, it should be ...
1
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1answer
128 views

Floating DC power supply (solar panels) - do I need double-pole breakers and why?

I am in the process of building a small off-grid solar setup. There will be 4 parallel strings of panels in this setup, and I understand that for 3 or more strings, you need some sort of over-current ...
0
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1answer
58 views

What sort of protection does a 2 pole circuit breaker offer?

I am trying to understand the advantages of using a 2 pole circuit breaker. I mean when the 2nd pole is used in the Neutral line in a single phase 230VAC system. Normally they cost more so they must ...
0
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1answer
70 views

Device for preventing 12V battery from dying

I am looking for a device which cuts off the connection between batteries and the system just like a circuit breaker when my 12V battery goes below 9V(for example) for preventing it from dying ...
0
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3answers
134 views

Rounding up or down with Motor Overcurrent Protection

When sizing motor over-current protection, CSA 22.1 28-200 3a states that a circuit breaker can be sized up to 250% of the rated full load amperage (FLA) of the motor. E.g. 100hp, 575VAC motor ...
0
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3answers
382 views

How can I check if two outlets are connected to the same electrical circuit?

I have some internet problems, and I was thinking to buy a PowerLine, that will help me extend the WiFi range. The thing is, to get this PowerLine working, both need to be conected to the same ...
0
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3answers
1k views

Can double-pole breakers trip each side separately?

How many of you have used double pole breakers? Are double-pole breakers just two single pole breakers physically joined? Someone stated that only one side of the double pole breaker provided ...
6
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2answers
1k views

Help identify this breaker

I salvaged this breaker unit from the scrape yard. Compared to every other breakers i have seen before, this is very different. It has 5 terminals. The labels are very clear but there is no ...
5
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4answers
5k views

Why cut both live and neutral wires?

It is a common practice, for high power loads such as boilers, furnaces, etc., to install a circuit breaker that "cuts" both live and neutral wires - at least in Europe. In my search for EVSE, I saw ...
1
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1answer
213 views

240v AC Circuit Breaker for 24v AC

I am essentially intending to use this Schneider Electric A9F44120 MCB as an automatic brake for my wind turbine, which has an output of 25A @ 24Vac. Can I use the normal 240Vac MCB for 24Vac? Will it ...
0
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1answer
39 views

Can you bridge off of a 240 V Breaker Box that connects to an Intermatic Timer?

I have an Intermatic T104 Timer drawing power from a Homeline Breaker Box for a home swimming pool. I'm wondering whether it would be considered safe to use the knockout in the timer enclosure to ...
0
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1answer
216 views

amp rating a circuit breaker

My application has a max Amp draw of 56@24Vdc, if I use a Circuit Breaker that is rated 60A@48Vdc, will it "trip" 60A@24Vdc? If not, what do you suggest? The Minn Kota MKR-19 Circuit breaker is rated ...
1
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1answer
959 views

When to use a 2 pole circuit breaker over 1 pole

We are currently designing a product that connects to 230VAC mains power (single phase) (South Africa). It has a simple 12v switch mode power supply that runs the electronics. We want to put a Circuit ...
1
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1answer
153 views

Full Load Amps vs General Purpose Amps

http://www.carlingtech.com/sites/default/files/documents/M-Series_Details_%26_COS_021114.pdf This circuit breaker have two different current ratings, depending on amperage range: Full Load Amps and ...
1
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1answer
61 views

What's with the minimum voltage rating on *some* IEC 60947-2 MCBs?

It seems that some, albeit not all, miniature circuit breakers have a minimum voltage rating under the IEC 60947-2 scheme (often 12VAC/DC). For instance, see the Sprecher/Schuh L8 series (PDF page 8) ...
0
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1answer
50 views

Are there disadvantages to this method of testing building wiring after a lightning strike?

A lightning strike can damage wiring in a building. Specifically it can damage the insulation on the conductors, resulting in arcing and fire, either immediately or some time after the strike. I've ...
1
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0answers
226 views

Circuit Breaker Simulation in Matlab with Mayr and Cassie Equations

I'm trying to understand how to model arc circuit breaker. There is a simulation example as called Mayr and Cassie Circuit in Matlab&Simulink. I have examined Mayr and Cassie Differential ...
2
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6answers
199 views

Why can closing a circuit breaker into a short circuit result in an arc flash?

NFPA 70E 130.6(M) states: After a circuit is de-energized by the automatic operation of a circuit protective device, the circuit shall not be manually re-energized until it has been determined that ...
1
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2answers
155 views

Is it possible for all circuit breakers in a panel to trip in the same time (for one fault)?

Today, I was in a hospital. Someone told me that there is a falt in a large washing machine. This fault caused all the CB's in the panel to trip. The panel has many circuit breakers of different ...
0
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2answers
151 views

Automatic cut mains power on a thunderstorm

I am a software engineer with only a basic experience with electric/electronic engineering. I live in a rural area subject to thunderstorms, my house is the end of the line from street poles. It's ...
0
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2answers
49 views

3 pole breaker and wire amp rating

In the main panel, there are 3 wires for 3 phase power going from 3 pole 40A breaker to a sub panel. the breaker is (CKIPSAL 4CB340/6 C40) The wires are in 2 cables. Each of these wires has 7 strands ...
1
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1answer
80 views

What could be causing this GFCI trip upon fan turn off?

I have a 2-pronged fan plugged into a GFCI in my basement. Twice now, as I was turning it off (out of maybe 30 times I have turned the fan off), the GFCI tripped. Now, I understand that GFCIs trip ...
-2
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1answer
64 views

Coordinated relay tripping for Protection in Modern Power System

I have been working on Etap Software to understand the basic protection scheme using Current Transformer, circuit breaker and Relays. But i am having trouble in the coordination of the tripping in the ...
2
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1answer
612 views

How does AFCI work?

GFCI / RCD systems are generally well documented in how they work (run both conductors through a loop of wire such that imbalance in current is measurable) -- but the mechanism by which arc faults are ...
6
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2answers
936 views

What is meant by the term “galvanic contact” in this sentence?

Simply speaking, a switch or circuit breaker are two metallic contacts (electrodes) that are in GALVANIC CONTACT with each other when closed and separated by a certain distance when open. I don’t ...
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3answers
416 views

Current through protective earthing

Is there a way to estimate the magnitude of the current that would flow through the protective earthing of an electrical equipment in case of a fault? I recently had an equipment fail in this manner ...
3
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2answers
2k views

What factors play into choosing type of MCB (Circuit Breaker) which is B16 vs C16 vs D16?

Found these discussions and Q&As online around this and am trying to determine how/ when one would decide to choose which way to go? http://www.theiet.org/forums/forum/messageview.cfm?catid=205&...
1
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1answer
7k views

I've seen many lighting circuits protected by 100mA ELCB instead of 30mA, why is that? isn't 30mA safer?

I've seen many lighting circuits protected by 100mA ELCB instead of 30mA, why is that? isn't 30mA safer than 100mA?
11
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3answers
1k views

How do I protect myself when testing a PCB that involves an AC line?

I have to test prototype PCBs that convert household AC into several DC voltage levels. I concern about my safety when working with AC and would like to know how to properly setup a testbench that, ...
0
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1answer
213 views

How can I power a load from two separate circuit breakers?

On one circuit breaker I have a manual switch. On the second circuit breaker I have a motion sensing switch (using a mechanical relay). I have a number of lights wired in parallel as the load. The ...
0
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3answers
117 views

Circuit breaker for single outlet

I have several 3d printers. One of them keeps tripping the breaker for the room. I'm trying to debug (obviously will not use it regularly until I can determine what is wrong) but in the mean time I ...
0
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3answers
4k views

Circuit breaker trip timing

I'm a little unfamiliar with circuit breaker specs and confused by this circuit breaker datasheet: https://www.waytekwire.com/datasheet/46974.pdf On the second page, it says that it takes more than ...
0
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4answers
227 views

(How) can IEC-specification miniature circuit breakers be interlocked?

A relatively common way of implementing a transfer or bypass/isolation function in North American electrical practice is to use mechanical means to interlock the handles of multiple circuit breakers ...
1
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2answers
383 views

Virtual AC ground for AC power main

I have the following problem: I use to perform electrical experiments in a small room in an apart where other persons repair computers. It sometimes happens that I make the main differential switch ...
1
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1answer
140 views

What's the use of the ground socket of an ungrounded GFCI receptacle?

Is the ground socket of a GFCI receptacle that isn’t connected to ground useful? (I'm in the United States, if it matters.) If the connected appliance had current on its ground pin, where would this ...
0
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1answer
602 views

Expected breaker temperature on a 208V 30A circuit with continuous 80% load

I have several cabinets of servers in a datacenter and each of these cabinets is on a dedicated 208V 30A circuit. The load on each of these circuits is 24A and one circuit is slightly higher (~24.6A). ...