33

When or is it NEC code compliant to upgrade a 2-wire circuit, by adding a third prong equipment ground from a nearby galvanized cold water pipe? Never! Article 250.118 of the National Electrical Code lists the approved methods of equipment grounding. Water piping systems are NOT listed there. Metal piping systems within buildings are required to be bonded ...


32

Yikes, good find! This is most definitely the reason. The ground and neutral are only supposed to be tied together at the main panel. In this case, instead of only the neutral carrying current, both the ground and neutral will carry it. There is no legit reason that I know of to do this at an outlet. I wonder if perhaps the neutral was open and the ...


25

Your house is wired using the EMT conduit wiring method. Individual wires are carried inside metal conduit. The conduit is the ground path. Most commercial and industrial buildings look exactly like this. Since they are individual wires, they are able to use any of 11 wire colors to disambiguate circuits, instead of the usual black white red. If you ...


23

The grounding conductor in an electrical system provides a safe path for fault currents to travel along. It's there to prevent electrocution. No Grounding Conductor Let's say we have a toaster. Inside the toaster are two conductors, a black ungrounded (hot) conductor, and a white grounded (neutral) conductor. To heat the toaster, current flows into ...


20

Just some sand paper will be fine. You don't want to use a chemical stripper as it may interact poorly with the copper.


18

The tester can't tell the difference. One way to look at is that electrically, since neutral and ground are already bonded at one location (normally the main panel), the electrons don't know the difference. But the other way to think about it is to look at what the tester is actually doing. What do the Lights Indicate? These testers are actually 3 simple ...


17

No -- that bond wire could save your life! It is very important that all non-current-carrying metal, including the cold and hot water pipes, be bonded to the electrical system ground. This prevents highly unpleasant surprises should a wire in the dishwasher come loose and contact a water pipe! Furthermore, this requirement is enshrined in 250.104(A) of ...


16

Filipino electrical service is a morass. There is some Euro 230V single leg service, and there is some American style 120/240 split phase service. And if those services are wired to Euro or USA standard, they'll be as safe. However, in actual practice, weird things get done in the Philippines. And there is a high rate of electrocutions. This is one ...


15

Someone forgot a fitting Normally, armored cables (like yours) are brought into a box using a fitting designed to clamp the the cable armor, grounding it to the box and also providing a strain relief for the cable inside. Your furnace installer didn't have that fitting on hand, though, so they simply shoved the cable through the hole and shoved a "redhead" ...


14

To answer your first question, no it's not permitted to have a 3 prong receptacle without the ground wire being attached. See some of the other questions explain how you should fix this situation. I believe the short answer is that it should be a 2 prong receptacle (which will be difficult to find and only to be used in grandfathered situations) or you could ...


13

It's called a bootlegged ground. This is commonly done in older houses that had a two prong receptacle and was updated to a three prong receptacle. The old house didn't have a ground and this tricks the inspector's electric checker, so your house passes inspection.


13

Grounding the 2 prong adapters has nothing to do with it. The point of a surge protector is to protect electrical devices from voltage spikes. A surge protector attempts to limit the voltage supplied to an electric device by either blocking or by shorting to ground any unwanted voltages above a safe threshold http://en.wikipedia.org/wiki/...


13

DO NOT connect the ground wire to the grounded (neutral) conductor, as this could lead to current flowing through the body of the dryer (and potentially through you). The installation guide for the dryer will have wiring instructions for both 3, and 4 wire configurations. Check the manufacturers documentation for proper wiring, but I would say the first ...


12

The correct answer is that you cannot install a 3 prong grounded outlet without using a 2 conductor with a separate ground conductor, that's three conductors. I know people cheat and put a wire from the ground screw of the outlet to the metal box and hope that the armor case is firmly connected to the box and grounded at the panel. This is not a good ...


12

Depends what you're trying to protect. If your goal is to protect the oven from ESD (static electricity) damage or lightning-strike damage, or help it receive radio signals, then going out to a ground spike can help you with that. It won't do a thing for human safety, though. To protect humans from electric shocks, you can go one of two ways. GFCI ...


12

The bare copper wires are the ground (grounds are either green or bare wires). You need to add the green wire from the dimmer to this bundle in the wirenut. The white wires are probably the neutral, providing a return from the lamp to your electrical panel. If you had a smart switch that needed a neutral connection, you would connect there. Note: this ...


11

Burnt wires are usually the result of a loose connection. When a connection is not solid, wires can heat up. This can be an even bigger problem with high amperage devices (heater, stoves, etc.). This likely has been an issue for a long time, and finally reached the breaking point. The problem with overheating wires, is that the issue becomes compounded ...


11

It is extremely unlikely that all three receptacles all have bad grounds. Not impossible, but unlikely. The most likely scenario is that your home was built before grounding became required by code (1962, plus however long it took for your state/municipality to adopt it), and then someone renovating after that time put in 14/2 Romex with a bare ground for ...


11

The accepted answer states "it's not permitted to have a 3 prong receptacle without the ground wire being attached." This is incorrect. 406.4(d)2(b) A non-grounding type receptacle(s) shall be permitted to be replaced with a ground fault circuit interrupter type of receptacle(s). These receptacles shall be marked "No Equipment Ground". An Equipment ...


11

In all my years I have never seen a device ground screw rated for two conductors. Even clamp type ground connectors found on GFI devices are only rated for one conductor. You will need to pigtail a single wire to the device. This can be achieved several ways. A green wire nut, a ground crimp, or a standard wire nut are examples.


10

You can't rely on the integrity of the ground/earth on the pipework of the sink. For all you know it could be connected to PVC pipework further down. In the U.K all pipework is meant to be cross-bonded which is then taken to the earthing bar. However in Japan I am unsure if this is what is done. Regardless you should be earthing/grounding it back to the ...


10

The instructions for the fixture are only correct for a metal box. If a metal box was used, the box itself would (should) be grounded. The bracket that holds the light would then be connected to the box, which would make the bracket grounded. Finally the ground wire from the fixture would attach to the bracket, grounding the fixture. In the case of a ...


10

That explanation doesn't really make any sense to me personally. The neutral bus bar in your main panel should be bonded to the ground bus bar so in effect, all neutral wires in your house are grounded. The third prong in a typical three prong outlet is known as the equipment ground. This is a safety feature that should cause your breaker to trip if an ...


10

The best way to check for the bootleg ground, is to open up one of the boxes and look at how the receptacle is wired. Since the grounded (neutral) and grounding conductors are bonded at the service equipment, they should always be at about the same voltage potential. If you had a long circuit, and an accurate meter, you might be able to measure a slight ...


10

Pick an electrical code Pick an electrical code and follow it. Pick one where your wiring system is normal. If your power is 110/220V split-phase (220V with the neutral center-tapped with 110V on each side), then follow a North American code. If your power is all 220V between neutral and "hot", then follow an EU code. On split-phase, neutral is serious ...


10

The ground wire should be properly connected back to the box ground connection, or back to the line ground if there is no ground connection in the box. Some will argue that the metal screws provide the grounding to the plate and so the ground wire is superfluous. However, there are two issues with that. The screws and the screw holes are very loose ...


10

Yes, it will misread. Because magic-8-ball testers are built for one thing: a quick pass/fail test for brand new wiring you just installed. Obviously, in new wiring, you don't have a bunch of the kinds of problems you have in old wiring, like people bootlegging ground off neutral. The device is simply not made to solve those problems. So if you misuse ...


10

Meet grandfathering: the idea that if it was legal at the time it was built or renovated, it's still legal. However, fitting ungrounded 3-prong outlets were not legal in 1965. What else could it be? It is legal to fit a GFCI (Europe: RCD) device. Circuits are typically wired in strings, and a GFCI device can provide GFCI protection to downline points of ...


9

If you are in the US, you'll likely follow National Electrical Code (NEC). Lets start with some definitions. NEC 2008 Bonding Jumper, Main. The connection between the grounded circuit conductor and the equipment grounding conductor at the service. Grounding Conductor. A conductor used to connect equipment or the grounded circuit of a wiring system ...


9

Considering there is some amount of either wrong, or maybe just misleading, information regarding your broad question which, in turn, can lead to ambiguities and poor and/or dangerous actions, I, a real electrician, will add my hat in the ring backed by the NEC. Because many people may search and find this post, as it is very generally asked, and in a given ...


Only top voted, non community-wiki answers of a minimum length are eligible