The actual electrical device can be designed such that it depends on exactly which direction is live and which is neutral.
Imagine a circuit loop that, as you follow along the circuit, has an AC power source, then a switch, and then the electrical appliance, leading back to the AC source it started from.
If you design the circuit so that you know for sure that the live wire goes to the switch first before the actual load, then your design ensures that if there is a fault or a short somewhere in the appliance, it won’t let the live power leak anywhere (because the whole device is only connected to the neutral line, not the hot live voltage that alternates between positive and negative voltage). It’s safer, and is less likely to damage the internals of a device. Especially if someone is going to reach inside and forgets to unplug it or cut power at the circuit breaker.
In practice tons of outlets are wired the wrong way around.
F actually has a convention for the socket, which is probably ignored even more often, but I would never trust live and neutral not to have been swapped somewhere regardless of outlet.
Just forcing plug designers to consider live/neutral being randomized in a very obvious manner might be safer in the long run than working on a partially broken system where someone manufacturer might be fooled into trusting it.
You have both live and neutral lines in the cable, coming up to a switch, which can either open the circuit on the live line or the neutral line. Then, the lamp itself has a single light bulb as the load.
If you place the switch on the live line, then the energy of the live line stops at the switch, with only whatever lower voltage is in the neutral line to actually be connected to the light bulb and lamp assembly.
But if you place the switch on the neutral line, you’re leaving the entire lamp on the voltage of the live line, which gives the voltage more places to potentially short circuit. If you were to take a non-contact voltage detector, you’d be able to detect a live voltage in the line leading up to the bulb, even when it’s not turned on.
You generally do this with the in-wall wiring and switches, too, and make the wall switches break open the circuit on the live line, not the neutral line. It’s just a better practice overall.
And no, the neutral line is not totally grounded, so it can still pose a danger, too. But safety is exercised in layers, and putting the switch on the live line is the better practice.
This is an entirely theoretical problem that just doesn’t exist in practice. Just to be clear, for it to short circuit, it’s needs to find a path to ground. It can’t just “go somewhere”. Just because the line is longer didn’t make it more dangerous for it to “just exist”. There are regulations for wires, which include frankly absurd safety margins, regulations for the electrical devices that are not optional either (CE compliance for example). It just complicates this for basically no reason to have keyd outlets.
It’s not electricity, exactly, but it is a higher voltage that is different from the average of everything around it. Electricity needs a closed loop to flow, and breaking open the loop with a switch means that no electricity flows, but the voltage of the live line goes up and down, creating an electric potential with anything that might be at a different voltage, if a conductor touches both.
Some people say it does with certain devices but I’ve never had anything I’ve run into. The American outlets have been used as bi-directional in most instances. (With 2 prong). If they had a ground then you can only go in one way. But that said… Obviously a cord without a ground can still plug into an outlet that has the ground set up. If the device wants the current to go in a certain direction they use one with a slightly larger prong on one side, but if you pick up any phone charger in America, you can plug it into any outlet any direction.
Phone chargers are definitely not the appliance that’s going to have an issue switching things out. That’s going to be stuff that directly uses the AC power. Some older appliances or shittily designed ones can even become an electrocution hazard when switching live with neutral.
It doesn’t matter depending on whether both are live. In plenty of places, only one side is live. Switching live with neutral can be very bad depending on the appliance, as described already elsewhere.
That’s bad.
Every device produced in the past few decades doesn’t care which wire is live.
Clear, informative and solution oriented. I wish all signs were this good.
Damn homophobes…
Why? It doesn’t make any difference with AC
The actual electrical device can be designed such that it depends on exactly which direction is live and which is neutral.
Imagine a circuit loop that, as you follow along the circuit, has an AC power source, then a switch, and then the electrical appliance, leading back to the AC source it started from.
If you design the circuit so that you know for sure that the live wire goes to the switch first before the actual load, then your design ensures that if there is a fault or a short somewhere in the appliance, it won’t let the live power leak anywhere (because the whole device is only connected to the neutral line, not the hot live voltage that alternates between positive and negative voltage). It’s safer, and is less likely to damage the internals of a device. Especially if someone is going to reach inside and forgets to unplug it or cut power at the circuit breaker.
In practice tons of outlets are wired the wrong way around.
F actually has a convention for the socket, which is probably ignored even more often, but I would never trust live and neutral not to have been swapped somewhere regardless of outlet.
Just forcing plug designers to consider live/neutral being randomized in a very obvious manner might be safer in the long run than working on a partially broken system where someone manufacturer might be fooled into trusting it.
Could you give an example of such a device? Seems like a bad design
A simple lamp can demonstrate.
You have both live and neutral lines in the cable, coming up to a switch, which can either open the circuit on the live line or the neutral line. Then, the lamp itself has a single light bulb as the load.
If you place the switch on the live line, then the energy of the live line stops at the switch, with only whatever lower voltage is in the neutral line to actually be connected to the light bulb and lamp assembly.
But if you place the switch on the neutral line, you’re leaving the entire lamp on the voltage of the live line, which gives the voltage more places to potentially short circuit. If you were to take a non-contact voltage detector, you’d be able to detect a live voltage in the line leading up to the bulb, even when it’s not turned on.
You generally do this with the in-wall wiring and switches, too, and make the wall switches break open the circuit on the live line, not the neutral line. It’s just a better practice overall.
And no, the neutral line is not totally grounded, so it can still pose a danger, too. But safety is exercised in layers, and putting the switch on the live line is the better practice.
That’s a lamp in theory, but do you know of any actual lamps being sold where this matters?
in the US it’s fairly common, so probably some American manufacturers would do it that way
This is an entirely theoretical problem that just doesn’t exist in practice. Just to be clear, for it to short circuit, it’s needs to find a path to ground. It can’t just “go somewhere”. Just because the line is longer didn’t make it more dangerous for it to “just exist”. There are regulations for wires, which include frankly absurd safety margins, regulations for the electrical devices that are not optional either (CE compliance for example). It just complicates this for basically no reason to have keyd outlets.
If there’s electricity reaching the bulb it would be lit no? So if I place the contact upside down, I wouldn’t be able to turn off my light?
It’s not electricity, exactly, but it is a higher voltage that is different from the average of everything around it. Electricity needs a closed loop to flow, and breaking open the loop with a switch means that no electricity flows, but the voltage of the live line goes up and down, creating an electric potential with anything that might be at a different voltage, if a conductor touches both.
Some people say it does with certain devices but I’ve never had anything I’ve run into. The American outlets have been used as bi-directional in most instances. (With 2 prong). If they had a ground then you can only go in one way. But that said… Obviously a cord without a ground can still plug into an outlet that has the ground set up. If the device wants the current to go in a certain direction they use one with a slightly larger prong on one side, but if you pick up any phone charger in America, you can plug it into any outlet any direction.
That’s not how AC works
That’s not Ground, it’s Neutral. Neutral is sometimes bonded to Ground, but they are fundamentally different things
Phone chargers are definitely not the appliance that’s going to have an issue switching things out. That’s going to be stuff that directly uses the AC power. Some older appliances or shittily designed ones can even become an electrocution hazard when switching live with neutral.
In the particular case the sign is trying to prevent it’s to keep lazy idiots from electrocuting themselves stringing up Christmas lights.
It doesn’t matter depending on whether both are live. In plenty of places, only one side is live. Switching live with neutral can be very bad depending on the appliance, as described already elsewhere.
Why?
Why?
No it’s bi-winning