5

It's more than that -- polarized plug make cheap single-pole switches much safer. For example, look at the extension strip: With a polarized plug, it is perfectly safe to have a single-pole switch there-- one just makes sure it interrupts the "live" contact With a non-polarized plug, one either has to put a more expensive double-pole switch, or to accept ...


4

There are 2 scenarios where 3 pronged earth-bonded plugs are used. when SMPS are a classic line filter is used to suppress outgoing noise. The noise currents are shunted to earth ground using Y caps on each line to <0.5mA of line frequency max. For safety reasons in case of ground fault and any user touching the metal ungrounded frame and another metal ...


4

If you have proper protection in your house, connecting a small load (e.g. a light bulb) between earth and live will trip the circuit breaker, while a load placed between live and neutral will stay powered. If the load stays powered no matter which wire you pick, then the wiring in your apartment is really screwed, to the point your insurance company may ...


4

As a rule, each CB must be dimensioned to protect the smallest unprotected wire in its circuit. In your schematic, the first CB has to protect the 4mm2 wire going to Room 1, but also 2mm2 wires going to outlet 1, outlet 2 etc., because those wires have no individual protection. Because of this, CB1 should be dimensioned to 15A or less. Otherwise, a 20A load ...


3

In the US, the current two-prong power outlet was invented by Hubbell back in the 1910s. Of course, Hubbell also invented the polarized outlet in the 1910s. Knapp at Hubbell also invented an grounded outlet that was incompatible in the 1910s (used in China and Australia today). At the time, both US and most of Europe used 110V to 125V with a neutral. When ...


3

The reason is historical. WAAY back in the old days the neutral was used as a ground. My dad grew up in the 30s and it he said it was very common for washing machines and drills and light fixtures to have their metal cases connected to the neutral wire. Since there was always a few volts on the neutral due to wire resistance it was common to get a tingle ...


2

The resistance of a ground rod is highly variable, depending on the soil conditions. In damp earth, it may only be tens of ohms. In dry areas you may struggle to get hundreds of ohms. If the soil resistance is at the low end, then there won't be a high resistance between the two rods. The ground around them will get hot from the current flowing (and ...


2

Like this: simulate this circuit – Schematic created using CircuitLab The switch is normally referred to as Single-Pole Double-Throw. (SPDT) (I had to look that up as it is called different in my native language) This in contrast to a standard on/off switch which is called Single-Pole Single-Throw (SPST). As you can imagine there are many other ...


2

You should read your insurance policy exclusions very carefully (even better, get a lawyer friend to interpret- they're good at finding worst-case interpretations). If you end up with a £100K lab it may not be covered. If you're planning on using cheap unapproved products that could cause a fire that may also be a concern, especially if they are mains ...


1

I suspect that terminology may be a local one but you have no location in your user profile. To me the most likely reason is for calculating total load on a system such as a transformer feeding a group of houses. Cookers will be used at somewhat diverse1 times and for diverse durations by each household so the expected average and peak load will be a ...


1

In most countries local regulations or electrical code will specify the type and size of wire required, and what wiring practices must be followed for AC power wiring. The size and type of wire used will have no effect on your electric bill. Your electric bill will be determined by how much electricity you use - turn off unneeded lights and appliances to ...


1

If you search hard enough, you will probably find that "it seemed like a good idea at the time." It provides some increase in safety to have the outer part of a bulb socket connected to ground. The same is true of certain internal parts of some products. Some parts are more at risk of contacting external metal parts than others. Sometimes design detail ...


1

The ground is there to protect you in the case of a fault most circuits don't have a GFCI on them, if there is a fault the circuit can still protect you. First of all Electronic Test Labs (ETL) like UL require you to fuse your product if you have AC mains running into it (I think an exception to this may be if it's double insulated, but I'll have to check on ...


1

No, the ground conductor is intended to protect the user should a single fault in the insulation of the mains occur. Appliances which use the ground wire will have it connected to the metallic case (if it has one) or any metal parts the user can come into contact with, and should a fault occur and the live wire come into contact with any of those parts, a ...


1

You will only be able to determine the power consumption of individual appliances by measuring each appliance individually. Measuring the current at the AC input to your home can only tell you the total power consumption of your home - you can't distinguish the power consumed by individual appliances there.


1

Typically the ground is green, not blue, but you do have the colors correct in the general sense (L black and N white). If the transformer doesn't have an input for the ground that will likely need to go somewhere else for safety so although the hook up is neglected for the transformer it is very likely still required elsewhere. As for the voltage of the ...


1

What disadvantage a setup like this would have? Assuming (North American-Style) Residential/AC conditions: 1) Adding another "different earth connection(2 grounds each connected separately the earth)" increases the possibility of the two grounds being at different potentials, causing all sorts of undesired secondary effects. The primary being the ...


1

With admitted 'less than basic' knowledge about electricity, that means you must not make any connections to the mains on your board. What you want is a clamp-on current transformer on each wire you want to monitor. This usually takes the form of 2 C-cores, with either a winding round one of them, or Hall sensor or two embedded in them. These will isolate ...


1

The CB protects the wires connected to it. At each node where the thick wire is distributed to thiner wires there should be placed CBs. For your example, the 1.5mm^2 wires are protected with 10A, 2.5mm^2 with 16A. The incoming 4mm^2 is protected before, at point where it was taken form thicker wire.


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