Questions tagged [earth]

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60
votes
9answers
32k views

Why on earth are o-scopes earth referenced?

Thinking about it: You would never find a "Grounded" multimeter as robust and useful if a path to ground through the multimeter were introduced, modifying the circuit's behaviour and possibly damaging ...
48
votes
10answers
29k views

Why is main's neutral tied to earth?

My dad is an Electrician and I myself am an Electronics Design Engineer, and to this day he still hasn't been able to give me a good reason for this. Consider the two following pictures/situations - ...
33
votes
5answers
22k views

Why don't we use neutral wire for to ground devices and earth wire for closing the circuit?

I know that the neutral point of a distribution transformer is connected to the grounding (earthing) wire, so I think they are the same. Can I use the neutral wire for protecting metal-cased electric ...
28
votes
6answers
85k views

“Ground” vs. “Earth” vs. common vs. negative terminal

This may just be me not having a degree in electrical engineering or electronics, but the whole notion of "ground" and "earth", when used in electrical circuit diagrams (especially integrated circuits)...
19
votes
3answers
5k views

Static shocks all over the building

I just came from the local library, it’s quite big, and most of it is made of an architectural design using mostly painted metal book shelves painted with some kind of anticorrosive paint along with ...
18
votes
3answers
20k views

Why is earth used for ground? Literally earth?

I never considered earth to be particularly conductive. It's just dirt, after all. However, I've seen "earth ground" conductive stakes driven into the ground in order for electricity to be grounded, ...
15
votes
8answers
5k views

What is the right way to float a home lab?

I just got myself some new toys for my lab at home like 30V DC power supply, KKmoon signal generator and a Rigol DS1052E. I want to float everything, because I don't want to spend any money on stuff ...
13
votes
6answers
2k views

How to stop plastic granules sticking to the iron wall of their silo?

In our factory, we have some large (8 meters tall and 3 meters in diameters) iron silos for storing the plastic compounding material. Every time the silos are getting unloaded from the granules, the ...
10
votes
2answers
6k views

Are countries that use 2-pin plugs less safe than countries that use 3-pin plugs given that the earth is missing?

Will there be occasions when using 2-pin plugs is safer than 3-pin plugs? Is it accurate to say that 3-pin plugs are always safer given the presence of earth?
9
votes
3answers
6k views

Why is chassis connected to earth ground but not neutral?

My question arose from my previous questions. Here depicts how electricity is distributed to houses:http://www.epanorama.net/documents/groundloop/feed_1phase.gif It seems like the earth ground and ...
8
votes
4answers
983 views

Is the link between the earth/chasis terminal and the utility transformer established through a dedicated wire or the soil?

I was following a tutorial on power supply transformers and at the very beginning I have encountered the following illustration: I added the names TG and HG for the LV transformer ground and the ...
8
votes
1answer
11k views

Why is earth pin absent in phone chargers plugs but present in laptop ac plugs?

Both mobile phones and laptop get dc voltage from ac source for charging.These chargers have transformer for isolation and rectifier + filter if i am not wrong.I guess the amount of output dc and ...
6
votes
5answers
1k views

The path of electrons in AC circuit?

I have a question regarding the AC circuit shown below. If we ignore the voltage drop caused by the long cable, I think the device will work and the circuit can be considered as a closed circuit. Now ...
5
votes
3answers
19k views

Why the neutral of the UPS or inverter or generator is advised to be earthed/grounded?

In my company we had few earthing related issues. When an consultant was brought in and apart from solving the issue, a suggestion was made to ground the neutral of the UPS and diesel generators that ...
5
votes
1answer
409 views

grounding a mailbox - isn't it already grounded?

I live right next to some suspended power lines. My mailbox is very close to them, and anytime I touch the mailbox, I get a mild shock. It seems to me I need to do something to ground the mailbox but.....
5
votes
2answers
4k views

Why do some electrical devices have a ground and others don't?

I noticed in my kitchen that the toast oven and the range hood had a ground fault, first by using a voltage detector pen, when getting near it the pen would activate from a distance (around 5cm ...
5
votes
1answer
5k views

Does potential difference exist between Earth ground in geographically diverse locations?

Earth ground is used as a reference from which all voltages are measured in systems which are earth grounded. Because the earth absorbs or dissipates nearly unlimited electric charge, it should always ...
4
votes
4answers
2k views

Resistor or low impedance path between common ground point and mains earth?

A simple EPA (ESD Protected Area) consists of 3 things: wrist strap antistatic mat common point ground Wrist strap and antistatic mat both should grounded to the common point ground. ANSI/ESD S6.1 ...
4
votes
2answers
237 views

Should I ground my case

I built up a LM317 power supply which is working great. I have moved it into a large case as I am now powering it off 240VAC (fused) down to 18VAC then rectified into the power supply. Which is going ...
4
votes
1answer
2k views

What is the effect on noise immunity of a floating shield on a shielded twisted pair

We have an installed system where resistive sensors are connected to some electronics by shielded cables of between 2 and 10 metres. The cable is a twisted pair sheathed in a stainless steel braid. ...
4
votes
3answers
7k views

How do I verify if a conductive mat is getting “Earthed”

Explaining to me about electricity is like explaining to your Grand-Ma about it. So please be kind and gentle :) I bought an Earthing Mat from "http://www.amazon.com/dp/B003RLOBOK". It includes a ...
4
votes
1answer
349 views

local/bench earth leakage for testing mains electronics

I sometimes find myself testing switch mode power supplies and such that I have repaired, and often some undetected fault causes them to trip the earth leakage breaker on the distribution board when ...
3
votes
1answer
322 views

Why conceptually we connect circuits to earth but in reality that doesn't really work?

This question is best seen with an image: Above we can see two equivalent representations of a circuit, on the left side we have a voltage source closed-loop connected to a Resistance (R), and on the ...
3
votes
1answer
388 views

Why does the Earth's electric field affect things so little?

Starting here: http://hypertextbook.com/facts/1998/TreshaEdwards.shtml "Over land the average electric field is about 120 V/m …. Assuming an exponential increase of the conductivity with altitude, ...
3
votes
1answer
874 views

Oscilloscope ground clips sparks while connecting to power supply

Oscilloscope ground clips sparks while connecting to power supply ground. I do understand The clip is connected to earth ground. But why does it not spark when I am powering a circuit of the supply?
3
votes
2answers
3k views

Should I connect a cable's shield to the ground layer of board when it's isolated from earth?

I have a controller board powered by DC that may or may not be isolated from earth ground. The chassis of the device is non-metallic. This board connects through a long (30-40m), shielded cable to a ...
3
votes
1answer
192 views

Strange Earth Voltage Reading

Ok, my first question here. In my spare time, I run a small PA company. On Saturday, I had a concert at a sports center where I´d never been before. Power for the event came from a standard 5-pin, 16A ...
3
votes
1answer
3k views

Grounding the chassis with capacitor

My question involves chassis grounding to earth ground. My PCB circuit is a simple signal generator using a microcontroller. It has a separate 'ground' from earth ground, supplied by a floating 5VDC ...
2
votes
2answers
979 views

How to mount a toroidal transformer in a waterproof plastic case

I have a toroidal transformer with mains input and 24V output, which I want to mount in an IP65 ABS plastic case. The transformer comes with two rubber and one metal disc for mounting, along with a ...
2
votes
2answers
299 views

Clamping the output ground very close to earth ground

I've noticed that the output ground of most power supply are not quite the same as earth ground. The DC is nearly negligible, but there is usually an AC component between output ground and earth ...
2
votes
1answer
349 views

What were to happen if I short-circuited electricity generated by a power plant to the Earth?

I'm not sure how to word this better, so I hope this makes sense. Let's say theoretically that I connected a cable from the hot side of the power lines that run along the road to a stake in the ground,...
2
votes
2answers
80 views

Live wire and ground question

I am trying to fully understand the danger of AC voltage but still I have some questions... I understand that human body has a capacitance that facilitates AC current penetration. I also understand ...
2
votes
1answer
108 views

Motor / VFD / Protective Earth

I have little experience with AC motors since I'm majoring in Mech.E. My team is setting up an AC motor with a VFD to control the movement of an airfoil inside a metal cage we built. I understand the ...
2
votes
1answer
334 views

Ground and earth layers on PCB

I am designing a digital board with USB input and output. Shield of USB is connected to a chassis ground as per USB specs and connected to GND through a R and C in parallel USB power has a common ...
2
votes
1answer
287 views

Earth ground to dsub9 shell

I have an enclosure containing an earth ground line. It has a brass earth ground bus that is connected to: the input earth pin of a 120V single-phase mains IEC320-C14 connector the output earth pin ...
2
votes
2answers
622 views

Is some protection necessary for a RS232 link between PIC-MAX232-Computer?

I have a circuit with a dsPIC which communicates to a computer using a MAX232 (there ain't any optical isolation). The circuit ground is not bounded to the earth. But the equipment case is earthed. ...
2
votes
1answer
452 views

How do physical connection interfaces handle floating voltages

I am sorry if this is a bit of a novice question but I am new to electronics and have come to a problem that I can't quite see an obvious answer for. A while ago I had a bit of a scary encounter when ...
2
votes
2answers
3k views

EM MWD Gap Sub Telemetry Theory Explanation in Drilling Applications

I have been doing an extensive amount of reading on EM (Electromagnetic) Telemetry in MWD (Measurement While Drilling) applications. From my reading, there are a few considerable gaps in my ...
2
votes
1answer
140 views

Connection between metal enclosure and 0V in industrial system?

I have been testing an industrial system. I have developed a test device to properly test this industrial system. I am currently finalizing the test device and have put it in an enclosure to EMC proof ...
2
votes
1answer
237 views

Modding a Class II switch mode power supply to have output dc- shorted to earth

As above, what are the disadvantages, risks and dangers involved in modding a class II switch mode power supply i.e. a double insulated laptop charger that is ungrounded to have the dc- output shorted ...
2
votes
2answers
620 views

What is the difference between capacitive fault currents and resistive fault currents?

http://uk.megger.com/battery-ground-fault-tracer-bgft\ This website claims that it's product can differentiate between these two fault currents. But I don't know what the difference is.
2
votes
1answer
996 views

Adding a resistive path between live conductors and earth - safety issues

(Note: I am in the UK so the terms 'line' and 'neutral' refer to the two live mains conductors) I am trying to establish a list of safety issues which I should be aware of if I decide to introduce a ...
2
votes
1answer
199 views

Earth Ground Portable Generator

I recently bought a pure sine wave 2kV portable generator to use for camping. In the manual it states that the generator should be grounded to actual earth through a metal stake and then attached to ...
2
votes
2answers
1k views

Ground Fault Protection in Unearthed HV Systems

I'm working somewhere that uses an unearthed 3.3kV network for safety critical drives. I've been learning about ground fault detection on ungrounded systems, using VT's and measuring voltage across a ...
2
votes
0answers
180 views

Should I connect stepper motor case to mains earth or power supply V-

I have a stepper motor driver, the sockets have the expected V+,V-, etc. However there is a bolt with a grounding symbol on the outside, I think this connects to mains earth? The third pin on a plug? ...
1
vote
3answers
87 views

I thought that the ground was different from “earth”! [duplicate]

According to Paul Scherz in his Practical Electronics for Inventors, he mentions in Chapter 2, Theory, the following: Typically, the earth, with its infinite charge-absorbing ability and net zero ...
1
vote
2answers
143 views

Connecting a battery powered circuit to the earh ground [closed]

In the following circuit what would be the effect of tying a circuit to the ground from the -2V rail ? I know that no current would flow to the ground since there is no closed loop formed, but ...
1
vote
1answer
124 views

Op. Amp. read variation when Earth is connected with Signal GND

I've made this simple circuit to read the line voltage (the 1 pin is conected in a uC by a resistor): In the image NEUTRO is Mains Neutral AC, FASE is Mains Line AC and TENSÃO is the signal to the uC ...
1
vote
2answers
2k views

What is the difference between neutral and ground?

What is the difference between neutral and ground? I do not understand the difference.
1
vote
2answers
127 views

Does Surge Spike Protector box can protect my PC even from Thunderbolts? [closed]

My house isn't wired for an Earth ground. I am using a Surge/Spike Suppressor box to protect my computer. Will this box protect the computer during lightning strikes? Is the design of the suppressor ...