If the neutral wire carries current, why do many people believe that it's safe? I've heard "You can touch the neutral wire/bar in the breaker box and not get shocked. Only the hot can hurt you." If the circuit is complete and current is flowing, can't you receive a shock?
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asked Jul 22, 2013 at 21:27
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17\$\begingroup\$ Because it takes no sides in war. It's also called the Switzerland Wire. \$\endgroup\$– PasserbyCommented Jul 22, 2013 at 22:31
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1\$\begingroup\$ This article on allaboutcircuits.com explains it well. \$\endgroup\$– YesItsMeCommented Jun 9, 2015 at 17:47
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\$\begingroup\$ What matters is the current through you and the voltage across you, not the current through the wire you touch. \$\endgroup\$– alejnavabCommented Dec 22, 2021 at 18:19
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5 Answers
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The neutral is NOT safe to touch.
When everything is working correctly, it should be at most a few volts from ground. However, and this is the big gotcha, if there is a break in the neutral line between where you are and where it is connected back to ground, it can be driven to the full line voltage. Basically in that case you are connected to the hot line via any appliances that happen to be on in that part of the circuit. Those can easily pass the few mA it takes to kill you.
This is not supposed to happen, but since failures can be lethal and costly, a extra layer of safety is built into the protocol and rules. It is irresponsible and needlessly risky to consider the neutral line safe.
This is why modern appliances either have two prongs and everything is insulated from the user, or three prongs and anything conductive the user can touch is connected to ground. In some past cases there have been appliances with polarized 2-prong plugs, but those are seriously frowned upon today. I don't think you're going to get UL approval for such a device unless it is fully insulated, in which case you shouldn't need a polarized plug.
answered Jul 22, 2013 at 22:07
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4\$\begingroup\$ +1, It's important these questions get answered properly. " .. or three prongs and anything conductive the user can touch is connected to ground." this is why is someone has modified a three prong plug it can be dangerous -> it's then possible to invert the plug. \$\endgroup\$ Commented Jul 22, 2013 at 22:18
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4\$\begingroup\$ Appliances such as lamps typically have polarized plugs because of the possibility that the user might touch the threads of a bulb which is being inserted or removed. If the Edison-base socket were being designed today, it would be constructed in such a fashion that no part of the bulb's base would be exposed while it was electrically connected to anything, but neither bulbs nor sockets could be changed to achieve that while remaining compatible with the variety of bulbs and sockets in use. \$\endgroup\$– supercatCommented Jul 22, 2013 at 22:30
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3\$\begingroup\$ In a sense, I think the idea is to ensure that people are to the extent possible at least two "faults" away from experiencing a harmful condition. The neutral wire SHOULDN'T be far from ground potential, and people SHOULDN'T be touching the neutral wire or anything connected to it (like a the base of a partially-inserted bulb) but neither condition in itself would be harmful. Since either condition would only be one "fault" away from causing harm, though, neither condition should be considered "safe". \$\endgroup\$– supercatCommented Jul 22, 2013 at 22:33
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\$\begingroup\$ Which is why I'm surprised the plugs we use in the US still exist. It's very easy to accidentally touch the metal blades when pulling out or inserting the thing. Why don't we have shrouds on them like say the C14 plug? Ugh. \$\endgroup\$– PasserbyCommented Jul 23, 2013 at 6:24
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\$\begingroup\$ @Passerby: It would be possible to design an outlet with a built-in switch, such that the contacts would only be energized when the plug was fully inserted (contact reliability implies that the contacts themselves should be relatively shallow). I doubt that the number of harmful incidents involving partially-inserted plugs would be sufficient to justify the added expense in most cases, though a "safety outlet" might be a good thing to have in e.g. a child's room. \$\endgroup\$– supercatCommented Jul 24, 2013 at 15:30
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On a non degraded correctly wired installation the neutral wire is safe because it is at the same potential than the ground terminal.
It is true that it carries current but because there is no voltage difference from ground there is no current passing through when you touch it.
answered Jul 22, 2013 at 21:32
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7\$\begingroup\$ -1 for a potentially dangerous answer. You're not wrong just incomplete and here incompleteness is dangerous. - on edit, removed DV \$\endgroup\$ Commented Jul 22, 2013 at 22:20
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2\$\begingroup\$ @rawbrawb Thank you for alerting me for that. I just modified my answer. \$\endgroup\$ Commented Jul 22, 2013 at 22:23
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3\$\begingroup\$ This is only true on a correctly-wired installation that has not degraded. All that is needed is a single break in the neutral, and you have full voltage on the neutral. \$\endgroup\$ Commented Jul 24, 2013 at 2:50
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1\$\begingroup\$ @EricGunnerson You are right. Modified. \$\endgroup\$ Commented Jul 24, 2013 at 9:32
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\$\begingroup\$ It is not strictly true that neutral and ground has the same potential. You will generally measure a few volts. The higher the load on the system, the higher voltage drop, and therefore a higher potential difference between ground and neutral. I dont have any numbers but I expect typically 2 to 10 volts. \$\endgroup\$ Commented Sep 7, 2019 at 4:42
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Consider the small appliance with dc transformer power supply such as TV and all appliances that have adaptor or dc transformer. And refer with illustration given by this link . It shows that the primary coil in line 1 is connected to line 2 nothing less and no bargain. The line 1 is a hotline and line 2 is neutral or common line which was actually connected each other. That’s the main reason why the neutral wire is not safe to touch due to the current voltage flowing from one line to another and when can we touch the neutral wire while working? In The Philippines we usually connect the Neutral wire to the ground rod, purposely to make it zero volts wire or the green wire serve as ground should be connected to the appliance. As long as there is a turning coil of wire on your appliance in that particular circuit, the Neutral wire will not be safe to touch unless there is an intimate relationship with the ground.
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It depends.
Under normal conditions the neutral is at close to earth potential but if the neutral goes open circuit then it can rise up to live potential and shock you. Similarly live and neutral could be reversed at some point in the supply system.
So the question then becomes "is the risk of a dangerous voltage on the neutral due to a break in the neutral wiring acceptable?". That is a question that is impossible to answer in the general case as it depends entirely on the circumstances.
On portable appliances I would always unplug before working. I would not consider plugs and sockets and thin flexible cables to be reliable enough to rely on the neutral remaining at earth potential.
On the other hand in the UK it is normal practice to work on circuits of an electrical installation where the neutral is not isolated. I don't know what practices are in other countries.
Going even further many power distribution systems combine the functions of neutral and earth. So do electrified railways.
answered Dec 11, 2015 at 16:50
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If the neutral is connected to the chassis, it will float above ground based on how much current returns to the panel and how much resistance the neutral return wire provides. V=RI. With a neutral on the chassis, there will be a constant small voltage above ground from the chassis during operation. If the earth is connected to the chassis instead, then the chassis won't float above the ground. That's it in normal operation. In terms of protection from a break inside the device that ends up connecting the live to the chassis, in either case (neutral chassis or grounded chassis) the fuse will blow. And in both cases, until the fuse blows, there will be a return current, going through a return cable (either ground cable or neutral cable) developing a voltage at the chassis. For a few milliseconds. Unless the return ground cable has much less resistance than the neutral cable, you'll get the same spike during the few milliseconds before the fuse blows.
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1\$\begingroup\$ I don't think the OP said anything about a "chassis". Why on earth (no pun intended) would you intentionally connect neutral to something a person would be likely to touch? \$\endgroup\$ Commented Jan 26, 2021 at 15:18