The Stack Overflow podcast is back! Listen to an interview with our new CEO.

# Tag Info

75

simulate this circuit – Schematic created using CircuitLab Figure 1 and 2. showing the danger of earthing through neutral. In the first example the Lunatic 'Lectrician has 'grounded' the lamp case by connecting it to the neutral wire. All appears OK although the customer notices a slight tingle when she touches the lamp when it is switched on. This ...

60

You are not really paying for the electrons that move in the wire, you pay for the force that moves them. It is like cutting a board with a hand saw. You push an pull it to cut the wood using the same teeth for each stroke. The electric company pushes and pulls the electrons and the moving electrons do useful things like provide light. You furnish all of the ...

39

I just had one of those last week. The plug was hot, and the socket was hotter. I'm the electrical guy so I popped it off. #12 stranded wire shoved into a smaller #14 backstab hole. Two thirds of the strands had missed the hole! Dumb things like that happen all the time, and you have to nip 'em in the bud the moment you see them. Don't use this ...

36

There isn't really any such thing as "electricity". The word "electricity" simply refers to the transmission of electrical energy, by using the motion of electrical charge. Electrical energy and electrical charge are not the same thing. In particular, electrical charge is not scarce or valuable; all matter contains electric charge, and, in fact, it all ...

20

The voltage on each pin, live or neutral, is irrelevant. Also the current flowing through each pin will be the same. The difference is the resistance of the connection the current is flowing through. This will be caused by the springs in the socket not making good contact with the plug pin. It's not unusual for heavy current users like kettles to make the ...

16

The two sides are out of phase with each other. When one side is high, the other is low, and vice versa. This is a 240 V outlet.

15

The electricity which comes into your home and you are billed for is not the electrons in the wire (which don't actually enter and leave, they just move backwards and forwards since it is alternating current that is being supplied). And the same quantity of electrons would be moving, whether you are running a single LED bulb or charging an electric vehicle. ...

13

While usually neutral wire and earth wire are at the same potential, and can therefore be effectively swapped from a purely electrical point of view, the way they are connected makes them very, very different. A domestic electrical system should always have two protection devices: the RCD, aka residual current device a circuit breaker The RCD is connected ...

11

It is all too easy to get a shock between "neutral" and earth or ground... Neutral is not always zero, some people make the mistake of assuming it is. With the effective length of some conductors, then when other devices are running there can be enough voltage present on the neutral to surprise you or cause you to hurt yourself... So, that is one reason ...

10

There is a problem. Generally the neutral and earth are connected at source. On fixed installations (e.g., your house) this may be the local transformer or at your meter-box, depending on local regulations. On your coach the generator / alternator most likely has its neutral connected to the chassis. The advantage of this is that we no longer need to fuse ...

9

The original article you've quoted is garbled. ... the voltage between any two phases is 3 times higher than the voltage of an individual phase by a factor of 1.73 (square root of 3 to be exact). It can't be three times higher and $\sqrt 3$ times higher simultaneously. The correct value is $\sqrt 3$ times higher. Figure 1. The diagram in question....

8

Vladamir has the important answer: we treat the two conductors differently, even though they are nominally at the same voltage. He gives the example of a RCD, and the GFCIs you see in modern US construction operate very similarly. The expectation is that the current flow of the hot wire and neutral wire will be equal in magnitude. If they are not, the RCD/...

8

The neutral wire is defined to be 0V. And each phase individually has a voltage relative to neutral of 115V if you are in the US, and 230V if you are in most of Europe. But because the three phases are 120 deg out of phase compared to each other this results in a voltage difference of 115V * sqrt(3) = 200V (or 230V * sqrt(3) = 400V) between any two phases. ...

7

I understand the use of ground wire at the home appliances but ... The earthing / grounding of applicances helps in two ways: It prevents the appliance case or chassis getting a high potential with respect to ground. Without this protection a live appliance (due to internal fault, for example) would present a risk to life should a person touch the ...

7

tl; dr: You should install a NEMA 14-50 (4-wire: L1/L2, Neutral and Ground) instead of NEMA 6-50 for best flexibility. NEMA 14-50 is the standard 'dryer' plug now, and it's what a car charger uses too. By the way, if you're messing with this, please consult an electrician. The fact that you're asking this at all makes me all kinds of worried. Now, to the ...

6

Answering the question in the edit: If the bulb is connected this way: If the customer touches the lamp when it is switched on, I do not thing she >will notice a slight tingle because the return path is the ground. If the neutral wire fell off, the metal case is not live. If the ground >wire fell off, the bulb will just turn ...

6

No. The UPS includes that connection when required internally. That's why there is a "UPS Neutral Out" UPS --> SPS Most consumer products labeled "UPS" are actually SPS systems. UPS (Uninterruptable Power Supply) means that the nominal power path includes the battery output. That way power comes from the UPS battery power path regardless of whether there ...

6

You're taking this "earth" or "ground" thing too literally. If I tell you: "There's 100 V DC on this node." Then then you would assume that I mean "100 V DC relative potential to the ground node of the device I'm measuring at that moment. You'd call me crazy if I said: "There's 100 V DC on this node relative to the metal hull of an oil-tanker which is in ...

6

One possibility is that your power supply is not single phase as you state, but rather split-phase. If that is the case, you don't have a hot and a neutral, but two hot wires. The two hot wires are 120V to ground each, and 180° out of phase, resulting in 240V across them. This would explain your 240V line voltage, your 120V hot-earth and "neutral"-earth ...

6

Your electrical devices allow a certain amount of current to flow through them. Lower powered devices draw proportionally less current than high powered devices. In simple electrical circuits the device's "resistance" determines how much current flows. What comes in on the live wire returns on the neutral wire. You pay for what you use. A little theory: ...

5

Yes, you have a problem. Basically, your "ground" is floating with respect to neutral. This suggests a failed connection, and this is potentially life-threatening.

5

To put all that was said in a simpler form, in case a layman stumbles upon this question: This is an indication that the plug/cord, the socket or both are defective and need to be checked ASAP, since there is a potential fire hazard.

5

... then why there is no current in the neutral wire? Yes, Virginia, there is a current.1. simulate this circuit – Schematic created using CircuitLab Figure 1. The building supply comes from the utility company's transformer. One of the transformer outputs is connected to earth and so is "neutralized. Current must return to the source as you ...

4

This Wikipedia page covers it well - but in short: Neutral is the return current conductor for AC power circuits. Ground (earth) is a safety connection provided as a separate return conductor for fault currents - i.e. it does not carry current during the normal operation of any connected equipment. Neutral and earth are connected together at the point of ...

4

You appear to be talking initially about the neutral wire in a 3 phase distribution system and given certain constraints on load imbalances, the "star point" imbalance current is usually a lot smaller than either of the three individual phase currents. For a single phase system (even if it is derived from a 3 phase system) you must make the neutral wire the ...

4

The manuf. insists that the neutral must not be solidly grounded. I believe this creates an unstable electrical environment for the machine electronics also, it creates a shock hazard under ground fault conditions. Am I thinking correctly on this? You don't use neutral for grounding. You use the protective earth, PE or earth point for grounding and, ...

4

If you follow your own logic through you'll have the answer. Since your phase to neutral resistance is close to zero then you can consider the phase and neutral as joined together (for the purpose of this exercise). Now if phase-GND is high resistance then netural-GND must be high too. This is correct. There should be no connection between the windings ...

4

AC current is sine wave with 60 hz frequency. No, the AC supply is sinusoidal voltage. The current waveform depends on the load but for resistor loads it will also be sinusoidal. ... how is this helpful in understanding electricity and transmission? It's not sinusoidal to help with understanding. It is sinusoidal because we use rotary generators and ...

3

"Carry voltage" technically is a very loose term. Voltage is relative, meaning it must be measured relative to another point, such as ground or another conductor. All conductors have resistance and obeys ohms law. When current flows there will be a voltage drop throughout the length of the conductor. This happens in all conductors disregarding the systems ...

3

In order to have a current you need a circuit... That is, you need a current path in both directions from a voltage supply. The biggest conductor on the planet is the planet itself. Although dry soil and dirt itself has quite a high resistance per linear meter, when you consider there are 1 trillion cubic kilometers of "earth" that's a lot or resistors in ...

Only top voted, non community-wiki answers of a minimum length are eligible