Questions tagged [gfci]

For questions about ground fault circuit interrupters (GFCIs), which are safety devices that break a circuit when they detect a leakage current to ground. Consider using in conjunction with related tags such as "safety", "protection", etc., if applicable.

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Static dissipation mat tripping AGFCI breaker

I have a home lab that I try to keep some level of static protection on, so I have a cheap anti-static mat that is grounded to a normal outlet in my lab. I recently installed a AGFCI circuit protector ...
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Please explain the interaction I observed between a GFCI receptacle and a 3000 volt arc

The high voltage leads of a 120 to 3000 volt transformer, current limited to 30 mA, were each wrapped around a small nail. The nails were allowed to rest upon a piece of wood soaked in an electrolyte. ...
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GFCI tripping when using hair trimmer, but only when using an extension cord

I have a GFCI socket in a recently-build bathroom. My hair trimmer trips it often when stopping under some conditions and while I have a fix I'd like to better understand what exactly is going on here....
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Should I expect the heating element in new cartridge heaters to be electrically isolated from the stainless steel exterior sheath?

I have two five-year-old 16 mm x 428 mm, 115 VAC, 1000 W cartridge heaters that have approximately 200 kΩ from the heater leads to the exterior stainless steel sheath. Is this normal or should I ...
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What are the implied peak current ratings of GFCI's?

Using GFCIs with transformer or other high-inrush current loads is problematic, because in some designs the differential transformer core can locally saturate and produce an invalid output in the ...
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1 answer
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What will happen if I press the GFCI button on an electrical tester when it is connected to a regular socket? [closed]

I know that the GFCI button on the tester engages the safety mechanism on the GFCI protected wall outlet. My question is: suppose I have a regular wall outlet, which is not GFCI protected, and is only ...
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Sensing Ground Faults on a High Voltage Pulser - Coupled Inductor Issue in LTSpice

I am building a ground-fault protected High Voltage Pulser. The pulses may be as high as 500V and as narrow as 50us (20kHz). The question of how to create GFCI protection is proving to be a ...
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Off-Grid Inverter causing a GFCI trip when charging EV

I have a transformer-less, 48VDC to 120/240VAC inverter that is off-grid. I have a 120VAC GFCI outlet wired to the inverter. When I plug my 120VAC EV charger into the outlet, the GFCI trips. It does ...
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2 votes
1 answer
80 views

How does a RCBO trip from a vapourised PCB trace?

I was replacing a power board with a new (plastic insulated) one, which resulted in a trip of the 20A 30mA RCBO on the circuit instantly upon turning on one of the board outlets. The built-in 10A ...
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5 answers
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Minimum current level to trip a GFCI

TLDR I originally asked "Minimum current level to trip a GFCI"? But the answers pointed out that my biggest problem in this question is that I shouldn't use a general-purpose DMM to find an ...
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1 vote
1 answer
165 views

How can I prevent my multi-meter fuse from blowing with a brief 120VAC surge?

I wanted to test how much power a GFCI outlet uses while idle, so I hooked up my multi-meter to test the current flow. I put my test lead in the amp socket, and confirmed the current was on the order ...
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1 vote
5 answers
468 views

120v Inverter and GFCI

I have a 48vdc to 120vac inverter with a 3 wire output (hot, neutral and ground). I installed a GFCI outlet using those output wires. I tried putting a resistor (I tested with 1k 100 and 22 ohm values)...
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2 answers
51 views

Selecting residual current for RCBO

I'm creating a portable test socket for electrical appliances that comes equip with a RCBO, power meter and possibly emergency stop button. My test socket will operate at max 240V AC and 10A. The ...
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1 answer
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Sanity check for current transformer burden resistor calculations

I'm hoping to use this(CR8420-1000-G) current transformer to detect ground faults of 20mA. Using the formulae in the datasheet: Here are my calculations: They say For best linearity, choose R ...
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1 vote
1 answer
144 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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1 vote
1 answer
157 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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0 answers
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Extension cord from grid through GFCI outlet to off grid inverter. Does the extension cord ground need connected?

I have an off grid system: PV, charge controllers, inverters, and batteries. I want to add a 120V grid input from a GFCI outlet through an extension cord directly into the inverter AC input. However, ...
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0 votes
1 answer
76 views

Can a grounded thermocouple cause GFCI to trip?

I noticed the tip of my soldering iron is case grounded. I understand the GFCI compares voltages and trips if there is a difference (in the millivolt range). If the thermocouple generates a small ...
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Automatic Self-Test Circuit in GFCI outlet

What kind of self-test circuits or method do they used in the GFCI outlets generally? Is it just firmware or is there a physical addition (and what it is usually?) This is because after 2015, it is ...
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