I have a 3 wire outlet with the entrances for hot, neutral and ground. But I know that the ground entrance is not really grounded, so in effect useless. Now, since the neutral is grounded, could I connect the ground entrance with the neutral therefore "grounding" the ground? What would be the problem with that?
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1If you don't have an EARTH wire DO NOT BRIDGE NEUTRAL + EARTH! This is potentially lethal as AC NEUTRAL is -220VOLTS! Earth is used in conjunction with LIGHTNING ARRESTORS and SHORT CIRCUITS prevention mechanisms! If you want earth- you need to UPGRADE your entire electrical system.– Piotr KulaCommented Oct 3, 2011 at 11:07
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13@ppumkin, neutral to ground should be 0 volts. If it's not, then it's not a neutral. For 220v circuits in the US, you have two out of phase hot connections at 110v each in addition to a neutral. That said, any issue anywhere in the wiring could result in an energized ground.– BMitchCommented Oct 3, 2011 at 12:24
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6@ppumkin google "Neutral Wire Facts and Mythology". There is a difference between neutral and hot even in AC circuits. One of the differences is that the neutral is grounded, therefore you shouldn't receive a shock if you touch neutral. Also notice that some plugs are asymmetrical so that you can't reverse the neutral with hot(the reason for this is explained in the document at the beginning).– Mr. RolandCommented Oct 3, 2011 at 17:48
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2@Mr.Roland - Yep good old hot chassis. You're bringing back the good old days of glowing electronics. It was a very serious and potentially fatal condition. The chassis was supposed to be ground and connected to neutral, but a miswired socket or replacement non-polarized plug with equal width blades (narrow blade for power, wide for neutral on polarized) meant that any exposed metal was hot 110VAC. All this for the same reason the shell on lamps should be wired to neutral and use a polarized plug. 3 wire plugs with ground force proper neutral unless the socket's been miswired.– Fiasco LabsCommented Nov 24, 2012 at 16:26
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1Replace the outlet with a GFCI, properly labeled "NO EQUIPMENT GROUND."– friedoCommented May 23, 2015 at 23:12
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6 Answers
Bridging the neutral and ground at the outlet is against code. This is called a Bootleg ground. You have a few different options to bring this up to code (corresponding to the NEC electrical code):
- Replace the outlet with a GFCI outlet, and leave the outlet's ground unconnected. This is minimally dangerous, the risk is if you get your body somewhere in between the hot and neutral.... but it'll protect you if current tries to flow between the outlet, and devices on another outlet (or the ground).
- Add an additional ground wire. The wire must be of the proper gauge, and go to a "grounding electrode", or your main circuit panel. There are a few other details that you'd need to follow. See NEC 250.130(C) for details.
- Rerun the wiring for the outlet with three-conductor cable/conduit.
- Replace the outlet with a 2-prong outlet.
Keep in mind that the ground and neutral should be connected together at your house's service entrance, and nowhere else.
The "ground" connector is often connected to the chassis of electric equipment, for example the metal case of your oven, lamp, etc.... One danger is that the neutral is not really at the same potential as the ground. The neutral wiring from your device has some non-zero resistance. The electric current flowing through your device also flows through the neutral wire. The current flowing through your neutral causes the voltage of the neutral to increase (based on Ohm's law, voltage = current * resistance), which can cause your neutral to be a few volts above ground. So, if you have a properly grounded device, next to a device connected to your bootlegged ground, you can shock yourself by touching the two cases since they will be at different potentials.
A second problem with connecting the ground to the neutral happens if your neutral wire breaks between the outlet and your service entrance. If the neutral breaks, then plugged in devices will cause the neutral to approach the "hot" voltage. Given a ground to neutral connection, this will cause the chassis of your device to be at the "hot" voltage, which is very dangerous.
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1Pigrew is essentially correct with an exception. The reason for the separation of the equipment ground and the neutral is that current flows on the neutral during normal circuit operation and you don't want current flowing on the equipment ground while equipment is plugged in. The ONLY time current should flow in any quantity on the ground is when there is a ground fault in the equipment. And this is intended to cause the circuit breaker to trip or fuse to blow. Commented Nov 16, 2015 at 0:10
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@ArchonOSX, I agree, though it should be noted that normal circuit breakers do NOT detect the ground fault current (in the case that the neutral and chassis are shorted). An AFCI or GFCI circuit breaker is required to detect that sort of fault, but it would never be able to be detected (even with a GFCI/AFCI) in the presence of a bootleg ground.– PigrewCommented Nov 16, 2015 at 18:07
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I think what you are saying is that the breaker can't detect a ground fault at the same level that a GFCI can (4-6ma) and that is true. They do detect ground faults, short circuits, and overloads at their setting level but at that level a human would be dead. Commented Nov 16, 2015 at 18:30
I don't believe this is up to code, but it will pass the test from a standard outlet tester. The problem I see is if any device plugged into the outlet comes into contact with a ground (e.g. water) and that path is more efficient than going all the way back on the neutral wire through the house wiring, then hot current going through any appliance and onto the neutral would come out the ground and possibly electrocute anyone in that path.
That said, I've seen this implemented and have lived in a home where this was done without dying, or even getting shocked. But the fact that the electrician that used this trick was missing several fingers should give you pause.
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"that path is more efficient than going all the way back on the neutral wire through the house wiring," Wouldn't this problem also happen if you had a correct outlet with a ground cable going through the house wiring? Commented Oct 3, 2011 at 18:02
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3@Mr.Roland, nope, consider if the neutral connection failed between the outlet and breaker. If you had a proper ground, nothing would happen since there is no path from hot to the ground. But with the neutral-ground connection, current would go from hot, to the neutral in the outlet, and back out the ground. If the device has a metal exterior, the entire surface is now energized and waiting to electrocute you.– BMitchCommented Oct 3, 2011 at 20:14
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If a system is properly grounded then any device that shorts to ground will trip the breaker or blow the fuse. That is the intention in order to protect people from energized metallic parts of appliances. Commented Nov 16, 2015 at 0:18
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@ArchonOSX yes, a hot to ground short would do that, but not an intentional neutral to ground short + a failed neutral downstream. Keep in mind this question is about wiring without a ground available and using a bootleg ground as a replacement.– BMitchCommented Nov 18, 2015 at 16:56
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1@ArchonOSX A direct short to ground can be enough to electrocute you without tripping a breaker or burning out a fuse, or before the breaker trips or the fuse blows. That's why GFCI's were created. Commented Mar 19, 2016 at 16:27
I'm not in the US. Where I live this (called "combined neutral and protective earth wire") is only allowed in non-domestic power distribution.
This setup has one major problem: if phase and neutral are swapped (for example, you alter wiring in the box next to the power meter and swap wires) phase is now supplied onto the grounding contact as well and that's asking for trouble.
So you can try do that, it's likely better than no grounding, but it's likely not up to code, and it is hazardous in that if wiring is altered you can have phase on the grounding contact and hence on appliance case.
answered Oct 3, 2011 at 7:38
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+1, great point. I believe if you swap the hot in this configuration, a standard outlet tester will indicate the error.– BMitchCommented Oct 3, 2011 at 11:09
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2Unless I'm missing something, I think the "better than no grounding" point here is key. Many people faced with a two-prong outlet will use an adapter that leaves them with an open ground. If an appliance plugged in there has a hot-ground short, the appliance exterior will become hot rather than tripping the breaker. If you wire ground to neutral such a faulty appliance will at least trip the breaker. Given that faulty appliances seem to me to be likely more common than a break in the neutral wire in the wall, it seems like ground-to-neutral is at least an improvement over open ground. Commented Nov 4, 2011 at 19:59
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4@CarlMeyer No, unfortunately. Remember that the "neutral" (the grounded conductor) is absolutely a conductor and carries exactly as much current as the "hot" wire. If you bootleg your ground, then you're energizing all the parts of any plugged-in appliance that are meant to be grounded. It might the metal housing of a toaster, it might be screws in a hair dryer--who knows. But you're energizing those parts and creating a shock hazard. Commented Mar 19, 2016 at 16:32
The ground is supposed to provide an alternate path to ground, in case the neutral wire doesn't do a good enough job. I don't know of any cases where the neutral would be compromised while a ground wire in the same sheath isn't -- except where someone mucked with the wiring.
If you only have two wires, that tells me you're in an older house. So it's possible (likely!) that a former homeowner did something wrong, like put a switch in the neutral, or reversed polarity. If you know all of the devices on a particular circuit, you can do the detective work to ensure that this hasn't happened.
Or you can run a separate ground wire to a water pipe. This does meet code in the US (at least as-of 1999, which is what my electrical handbook is based on), and it's what I did for my home office (I wasn't happy having computers on ungrounded circuits). To completely meet code, you need to ensure that the cold water pipe has a conductive strap to bypass the water meter. And you need to use a wire that is the same gauge as that used for the circuit (14ga for a 15 amp circuit).
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Your answer is not entirely correct. the "earth" wire detects leaks on applications that could be fatal to the user. EG electric boiler element burns out and the boiler becomes a "live" box- Earth detects this leakage and cuts the MAIN power to the DB(by electrical code) In the case of alternative route a SURGE PROTECTOR/LIGHTNING ARRESTER NEEDS TO BE INSTALLED IN CONJUNCTION WITH EARTH LEAKAGE CIRCUIT! to server as an alternative over current route. Commented Oct 3, 2011 at 15:16
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@ppumkin - I see that you're from the UK. Based on the wording of the question I assumed (perhaps incorrectly) that the OP was from the US. I'm not familiar with the European system, but based on your comments I'll assume that it's the same as the US 240V system. The US 120V system, however, does have a "hot" and "neutral" wire, and the neutral is wired to a grounding strap at the box. Perhaps there needs to be separate tags for "electrical-us" and "electrical-uk". Commented Oct 3, 2011 at 16:08
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1Electricity is the same all over the world.. standards are the problem though. It is most likely that the negative that is wired into a grounding strap must be connected to a rod that goes in to the earth somewhere outside. That is an old way of doing things and works well for lighting protection. but has some problem with appliance / user protection. I was actually certified in South Africa and understand the importance of lightning protection- but all new home builds(in ZA) do not have long rods into the earth any more and lightning poles are optional. Commented Oct 3, 2011 at 16:15
nuetral should be connected to ground so that any appliances touch the hot wire you will not be electricuted because even one hot wire touch any appliances and your stepping on the ground or holding any metal and touch that appliances you will be electricuted and that metal your touching will serves as ground.
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3This is just wrong. Don't do this. Neutral and ground should ONLY be bonded at the main panel.– StevenCommented Nov 3, 2012 at 15:37
There is no such thing as neutral in electricity. That would mean not being used. the neutral and ground are both ground paths. The issue is that the ground wire is usually used to dissipate static. while it should work and cause no problems I would not want to trust it with a pc or power tool. Both wires run to the exact same bars on a breaker box so in theory itll be ok but now you'd be trying to get rid of static down a line trying to deal with power from the supply side.
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1Sure, one of the roles of the ground is to equalize voltage throughout a local electrical system (aka your house), so you could refer to that as dissipating static. But that's not all it does. The "neutral" is more appropriately called the grounded conductor. It is a live circuit conductor. Yes, it is grounded, but you must not bond the neutral and the grounding conductors anywhere other than the main panel. If you do, you can end up energizing the metal housings on appliances, energizing your water pipes, and more. It's dangerous, don't do it. Commented Mar 19, 2016 at 16:40