electricitygrounding
On some stoves I've seen stickers stating that the stove doesn't need to be connected under the earth leakage… Which is rather confusing since we need to earth it in case of earth faults.
I'm just struggling to understand why a stove shouldn't be under earth leakage. Any information on this will be appreciated
The reason this is confusing is because the ideas are confused, mixed up in the word "ground".
Sometimes “earth(ing)” is used to refer to the concept of electrically connecting to the earth, allowing “ground” to be used for the concept of “a part of the circuit we consider to be 0 volts”.
Some say Ground is just a reference point for measuring voltages
That's one of the meanings. You have some device, some circuit, and say that this conductor is 0 V and measure everything else relative to it.
If the device is isolated (battery powered and not hooked up to anything else), then it's truly arbitrary, but if you have connections, signal or power cables, to something else — power supply, digital signal, analog audio signal, whatever — then the expected electrical characteristics are generally such that the two devices share the a common 0 V reference — a common ground.
(If there's a problem so that one of the devices is causing current to flow along different parts of the system that should be the same “ground”, that's called a ground loop.)
some say ground is a safety device for appliances
The safety device here is the presence of a connection between the chassis of the device (generally, any exposed metallic parts) and the “ground” conductor of the electric circuit, which is also joined to earth. The safety comes from the idea that if somehow the chassis gets joined to line voltage (“hot”) and current will flow to the “ground” (and perhaps trip a breaker or GFCI/RCD device) instead of through you when you touch it (as you are a higher-resistance connection to earth).
some say ground is just a bare piece of metal regardless if its even connected to the actual earth
A bare pice of metal is never “a ground” by itself. It's just common, for safety reasons and for electrical design convenience, to design things so that all exposed metal is joined to, or a part of, the circuit's “ground”.
Can you not be safe just by touching a hot wire alone, granted you don't touch neutral?
If you jump in the air and poke the hot wire, you're certainly safe. If you're touching anything else, like what you're standing on, you might be able to make a circuit.
What if you touch a hot wire then, stick you other finger in the dirt (soil)?
So its telling me that the current flow from a hot wire, to the grounding wire-> (connect to some rocks and dirt/poop) is so high, it can trip a breaker?
Depends on the kind of dirt, and how wet it is. If it's sufficiently conductive, the circuit consists of the incoming electric service (hot branch) → house wiring → you → dirt → service ground connection at the breaker panel → service neutral. (That is if your wiring is like USA wiring, at least.)
But safety grounding isn't just about “dirt” — think about the kitchen. You've got electric appliances, salty (conductive) water involved in cooking, possible spills and/or damaged wiring —
In a DC situation there is no hot wire, and
This is true but misleading. The reason we use the term “hot” with AC only is because AC voltages reverse all the time and so we can't just say “the positive wire” or “the -5V wire” or such. A way to describe either case would be to say “not at 0 V”. (Nominally in that resistance in wiring means that almost nothing is at exactly 0 V.)
(correct me if i'm wrong) but if I have a 350v Capacitor fully charged, there is absolutely no way for me to get electrocuted unless I touch both terminals.
If you had a 350 V AC power source that was isolated, then you could touch one terminal and be just as fine as in the capacitor case.
(Well, mostly fine. Because AC can pass through capacitors, and lots of things are a little bit like capacitors, there could be some current flow, though not much if the other terminal isn't connected to anything and therefore has no opportunity for capacitive coupling of its own.)
But your household AC line supply is not isolated — the neutral side is joined to earth — so it is not safe in this way.
people say step 4 is to ground that wire, How? The car is insulated from the earth All I see is an open circuit.
What they're not showing in the picture is that the “Yours” car is assumed to have the negative battery terminal connected to the car's metal frame, thus completing the circuit in the picture.
The reason for that hookup scheme is not anything about the electric circuit itself — it's because the final connection when current starts to flow may make an arc for a moment, and you want that arc to be away from the battery so it doesn't ignite any hydrogen gas that may be in the vicinity. (Mistreated lead-acid batteries electrolyse their water and thus produce hydrogen gas.)
AC power distribution systems are two wire circuits for delivering the current to the load. The hot wire conducts the current to the load on the positive AC cycles and from the load on the negative AC cycles. The "neutral wire" is used to conduct the corresponding current from to the load. It conducts current from the load on the positive AC cycles and to the load on the negative AC cycles. The use of the two conductors (Hot and Neutral assures a low resistance circuit path to make the distribution as efficient as possible).
For safety reasons and attempts to stabilize a local reference for the AC power distribution network the "neutral wires" are connected (bonded) to an actual earth ground connection at the entrance to the facility. This means that any given time there is a potential current path from the hot wire through a person's body to anything that is part of the nearby earth ground, be that through wet dirt, damp concrete, water pipes that go into the ground, metal building structures that are buried to foundations in the ground and even water paths to the ground. Any such current that is over some threshold through the human body is lethal. To mitigate this danger the standardized and codified electrical systems in most countries and regions these days require that all AC power distribution systems provide for a low impedance additional conductor path (safety ground) from the usage point (outlet for example) back to the facility entrance point where these additional conductors are tied in common to earth ground and to the "neutral wires". This low impedance path is intended to be connected to any thing that the user may be able to touch that is conductive on an appliance or fixture. The idea is that if there is some type of accidental short from the hot connection inside the appliance to the metal parts of the unit that people can touch that any current that wants to flow would take the preferential path through the safety ground wires back to the service entrance as opposed to going through the person and back through some other path.
These days many circuits in homes and businesses that are located near water, water pipes and other grounded metal systems are required to be equipped with ground fault circuit interrupters (GFCI). These units are designed to constantly monitor the current on the circuit and compare if the current on the hot side of the circuit is within 5mA of the current flowing in the "neutral wires". If they differ by more than this amount then the GFCI trips and open circuits the load point from the power feed. An imbalance could happen in cases where some person touched some metal part of an appliance or fixture where there was a fault or insulation breakdown. Some current could go through the person and into the nearby earth ground network back to the service entrance. Any current over 5mA is considered potentially lethal and so the GFCI trips to protect the user.
Note that not all appliances and devices are equipped with three prong power cords to take advantage of the safety ground feature. Such devices these days, that are manufactured and distributed by honest and reliable businesses, will be designed in such way that it is deemed safe to use the device even if there is an internal short or fault associated with the hot wire connection. These devices often have external plastic cases and are sometimes referred to as being "double insulated".
Best Answer
The sticker is not saying that the stove does not need to be earthed. It is saying that the stove does not need to be protected by an earth-leakage circuit breaker.
simulate this circuit – Schematic created using CircuitLab
Figure 1. A domestic fuseboard layout - Irish style.
Due to the amount of steam and spillages produced in cookers and stoves the likelihood of earth leakage is quite high. If the stove was protected by an earth leakage circuit breaker (ELCB / RCD / GFCI) nuisance tripping would become a problem. Because the stove is a fixed installation and more likely to be installed professionally the assumption is that the earth connection will be good and protect the chassis from reaching dangerous potentials. Similar decisions can be made for water heating, etc.
The highest risk of electric shock comes from portable appliances where cable damage, DIY errors, and accidents such as cutting through the hedge-trimmer cable, etc., are common and so earth-leakage detection is applied to all power sockets.
Interestingly lighting circuits can also be exempted on the basis that the number of accidents resulting from people stumbling around in the dark trying to find the fuseboard would exceed the number of electrocutions from lighting circuits which tend to be well out of harms way.