Why fuse is connected to the live wire

Characteristics: High resistivity. Low melting point. The same may happen if the fuse is connected to neutral. Because the fuse can disconnect the circuit only when the excess current flows completely through the neutral.

But, a circuit can complete or obtain a conduction pathway either by the neutral or earth. The fuse contains a thin wire that will melt if the current gets too high.

If there is a fault that causes the casing of the device to become live, a large current will flow through the low-resistance earth wire.

This high current will cause the fuse to melt. Asked by: Ammara Wiertz home and garden indoor environmental quality Why must fuse be connected to livewire?

Last Updated: 20th October, The fuse is connected to the live wire so that the appliance will not become charged have a potential difference of V after the fuse has melted due to excessive current. Fuses must be fitted onto the live wire so that when it blows, it will disconnect isolate the appliance from the high voltage live wire. Aminata Ouedraogo Professional. Can you fuse a neutral? Single Fusing. Tinka Cristina Professional. Why do fuse holders melt? Cause: If the fuse itself has not blown but the fuse holder has melted , it indicates that the equipment is not drawing excessive current, rather that the fuse holder was making poor contact with the fuse.

Heating in an electrical circuit is always caused by current flowing through a resistance. Grethe Bucheler Professional. What happens if live is connected to neutral? Originally Answered: What happens when a live wire and neutral wire came in direct contact? If the live wire directly come to the neutral wire it is the condition of short circuit.

In case of Normal wire the wire will burn and then the circuit break and all things become normal except that conductor or wire. Baralides Bradshaw Explainer. What will happen if switch is connected to neutral wire? If the switches were connected to the neutral wire , then there is a potential danger of an electric shock. Now, if the switch was connected in the neutral wire , then there's a good chance that we may come in contact with the path taken by the current and get an electric shock say, while repairing the bulb.

Parmenia Semper Explainer. Can you switch neutral? No, you don't want to switch the neutral. The neutral wire is connected to ground at the breaker box, which is connected to physical ground nearby.

If you switch the hot line and leave the neutral , then the whole device will be at neutral potential. Resistance from outlet back to panel x current draw will be the voltage increase over ground.

The neutral wire stays close to 0V w. Having a fuse on the live wire switches off the load, and brings the whole circuit close to 0V he neutral wire remains connected , making it safe to touch.

A fuse in the neutral wire would switch off the load, however, the load would remain at the potential of the live wire, so you'd still get a shock if you touched it. Loads are either isolated, or use a third terminal in the plug protective earth connected to the case. The PE terminal carries essentially the same voltage as the neutral wire, but its contact in the plug is asymmetric, so it's impossible to plug in the load in a way that connects the case to the live wire.

No, it doesn't. If you imagine wires as pair of strings, the neutral one hangs motionless, while the Live one is swung wildly up and down, ending above or below the neutral string. The load a rolling pin for example rests on these and takes the energy from height difference. House installation fuse - yes, it must be on Live wire, so it gets disconnected the moment something bad happen.

In case of house wiring, we know which wire is Live, because they are screwed in and not going to change, unless someone really messes up the service panel outside your house. Internal appliance fuse. Here all bets are off. The plug could be put in either way, or maybe someone swapped Live and Neutral in the socket by accident.

What really matters is that fuses breaks the connection between Live and Neutral somewhere inside appliance, making it stop. The fuse is still on what "should" be the Live wire, but it is not externally guaranteed. The appliance is none the wiser which wire is Live, it only cares the voltages swing up and down between the two.

The term "alternating current" refers to the fact that, if you just connected these wires through a resistor, current would flow from the live wire to the neutral wire when the voltage of the live was positive, then would flow back the other way when the live wire has a negative voltage.

The neutral only serves to carry current - the voltages pushing this current around are provided by the live wire. If you switch the wires, the potential difference between the terminals stays the same changing between V and V regularly , so plenty of electronic components will work either way.

The massive difference between the wires is how they react when exposed to electrical ground. A neutral wire shouldn't do anything as its voltage is already nominally the same as ground. A live wire will start pushing and pulling current to ground. A relatively common risk is that a person might touch a circuit while also being somehow connected to electrical ground - and the question is how to protect such a person. To justify placing fuses on the live side, consider the following dangerous situation: You stick a metal object into an outlet, connecting the live and neutral wires.

A great amount of current flows through it. A fuse blows disconnecting the circuit. The fuse disconnects the neutral wire. The metal object is now connected only to the live wire and exposes a voltage which regularly shifts between and volts. This is dangerous - if you touched the metal object and something else connected to ground, current will flow through you. The fuse disconnects the live wire. In this case, the outlet is now connected to the neutral only. At least in theory, the metal object is connected to ground through the neutral wire.

Both options will stop current from flowing through the errant object - so at least you won't be setting your house on fire in this thought experiment - but we should prefer option 2 because it merely exposes a neutral wire, which is not as bad as exposing a live wire. You are describing what's called an IT system. In an IT system, the two wires are indeed completely equivalent. Fifty or sixty times per second, each wire alternates between being positive and being negative positive and negative, not live and neutral!

Now imagine you touch one of the two wires. This wire is now connected to ground via you, but nothing happens! Everything keeps working, as you're not in series with the circuit.

You might think this is great, and it kind of is, and IT systems are often used in settings where people's life depends on the electricity staying on e. The disadvantage is that this might lead to a false sense of security.

Nobody knows that you're touching one of the wires! So imagine someone else, at the same time, touches the other wire. Unless you're perfectly isolated from each other, you both are now part of an alternative branch in the circuit.

The electricity goes from the circuit, through you, into the ground, through the other guy, and back into the circuit. The problem though: the system has no way of knowing whether you're a device being plugged in, or two people being electrocuted!

So it will stay on and keep electrocuting you both! This is the reason IT systems are never used in household installations. Instead, one of the two wires is permanently connected to the ground.

This wire is then called the neutral wire. The other wire isn't attached to the ground, and is called the live wire. Now, if you touch the neutral wire, nothing happens, like before. The wire and you via the ground are always at the same voltage.

Note that in countries with good safety regulations, there needs to be something called a residual current device that will notice this happening and shut off the electricity anyway, just to make sure. If you touch the live wire, that's now dangerous.

That's why all regulations are designed to avoid people coming into contact with the live wire. The reason the live is fused is similar as to why the live is switched and not the neutral. If you switched the neutral, voltage would still be present in the load. By switching the live wire; we ensure that the load is isolated when the circuit is switched off. The situation is similar with a fuse. A fuse is designed to protect the equipment and people from a short circuit. There are two cases;.

In situation 1, it doesn't matter where the fuse is located the fault current will flow through the circuit and blow the fuse wherever it is. If the switch or fuse is placed in the neutral wire, the electrical appliance is still connected to the high voltage live wire even when the switch is open, or the fuse is blown.

This could cause the user to get an electric shock if they touched the inside of the appliance. Appliances encased in an insulating plastic case or body, such as hair dryers, mobile phone chargers and hand whisks do not need an Earth wire.

Such appliance are designed so that there are two levels of insulating material between the electrical parts of the appliance and any parts on the outside that can be touched.