Electrical: Power Supply to Dishwasher has no ground wire?

The armored cable (sheath) is the ground.

OMG. So many answers that contradict each other. How are you doing to choose which one is correct? If you knew the correct answer, you wouldn't have asked the question so you need help picking the correct one.

Dragonfire was probably the closest. He/she was correct, but left out a suggestion.

Volts, amps, watts, water, hose, buckets... The analogy to water is pretty common because you can see water. Volts are like the water pressure. Water pressure determines how fast the water is flowing, but not how much. Think about a hose that you pinch off at the end. The water squirts further, but less comes out.

The total volume is like watts. That is what determines how fast the bucket fills. It is a product of the flow rate, and the amount of water that can pass though the pipe. In the case of water, the bigger the pipe, the more it is capable of flowing at any given pressure. Okay, enough with the water. I'm not sure you really even need to understand that.

You do NOT need a GFI on this because the case of the dishwasher will be grounded and there is no chance of touching the wires once the job is complete. I think some people misunderstand the rules.

Years ago, they used to consider the metal shield an adequate ground, but they no longer do because it is not reliable. This is because of physical problems that can be in the circuit from the breaker box to the appliance. One missed connection and you have no ground.

We also assumed that there would not be a hot wire ever touching the case. As it turns out, that was not a good assumption. It doesn't happen that often, but when it does, someone can get killed. Not a good risk.

That is why a separate ground wire is now required. It is true that the neutral is at the same voltage level as a ground. Actually, there are literally connected to the same bar inside the breaker box, so they have to be.

They are run in two separate wires so that the ground can be treated special for safety. The ground is connected to the frame of the appliance. That way, no matter what is done with the hot or the neutral, the appliance case can not possibly shock you, no matter what. Under normal conditions, there is no current flowing through the ground. 100% of the current flows though the hot and the neutral.

This is kind of like the bumper on a car. It just sits there and does nothing, ever. Except then there is an accident involving the front or rear end of the car. Then it takes the brunt of the force that shouldn't be there. Hopefully, by it taking the force, you will not have to. It may be destroyed in the process, but your injuries are hopefully lowered.

What Dragonfire did not suggest is that you can run a separate ground wire without removing everything. It would be better to run it inside the metal shield, but it is safe to run it outside the shield. They make a special lubricant just for making wire slicker to run inside conduit easier. That might help you.

The wire should go from the breaker box to the appliance, if possible. If you have to cut and splice, then you have to. If not, I like to not cut it.

The dishwasher can be plugged in or directly wired into the box, your choice. Since you are not taking it out and putting it back in periodically, it really doesn't need an outlet and plug. Personally, I don't put in a switch either. You would never turn it on and off, like you would a garbage disposer.

I do not know what code says. In this case, I really don't care because no one is going to inspect it and it is completely safe. If there was even the slightest danger, I would put one in. There is not.

Hope this helps sort out the good, the bad, and the ugly.

box under the counter? is that junction box? or do you mean a receptacle...

dishwashers do not need to be GFCI protected

but they

DO need a ground

as it a major appliance

and that's to ensure a ground fault path back to the panel from the motor of the dishwasher.

so under the sink there should be a receptacle ( 3 prong u ground or a NEMA 5-15-R ), and coming from the dish washer you would have an applaince cord 3 prong

but the way you describe it makes me to believe the dishwasher was hardwire into the "box" under the sink

that's fine as long there is a means of disconnect

usally a 20 amp single pole switch works or in the other case and what is normally done a receptacle and cord.

any flexible armored sheath is no longer code as use for grounding

any flexible metallic conduit must provide a ground path via seperate ground wire along with the conductors

sounds like you have a "flex" going from dishwasher to the box

inside you should indeally have 3 wires

one black

one white

and one green

old 3/8" diameter armoured cable known as bx typically was steel jacketed and thus used the armour housing as ground

provided you use 2 screw bx connector which are tightly locked ringed to the steel junction boxes. but as other noted you cannot account for others workmanship which is one reason it's no longe permitted

PS

Frozen is correct in his anology

Tiffany has it wrong

Your "flexible armored sheath" is only a ground if it goes ALL THE WAY TO THE SERVICE PANEL. A dishwasher is considered a major appliance, and it should have it's own breaker, as should the refrigerator, microwave, and furnace. Being that there is water present in a dishwasher, a good ground is an absolute necessity, for obvios reasons. Although some of these posts contain good advise, you need to contact a LICENSED electrician to be sure your power supply to your dishwasher is safe. Electricity kills, and bad wiring burns down houses.

Ok, I don't know much about electrical... However........ My hubby is a journeyman electrician and has been for many years. Here's his answer to your question.

First off, you have been given incorrect information. Watts is not the same as volts. Think of electricity as water going through a garden hose. Wattage is equal to the amount of pressure is within the hose. Voltage is equal to the rate of water coming out of the hose. So to clarify Scooby's statement, you are more than likely working with 240/120 voltage residential power. Which means, your house is wired standard. The amperage on the breaker for the dishwasher, should be a 20 amp breaker on it's own circuit.

Now the question about the equipment ground- in older homes, (pre 1970), most grounds were considered optional except for plug-ins. As per my understanding of the NEC code, the amour on amour flex cable can not be used as a primary equipment grounded conductor. So yes, you need to update your cable, (MC cable will work for this purpose), or change the cord on your dishwasher to a appliance cord that can plug in to the wall with a ground. You should be able to find either one of these at your local hardware store.

My suggestion, is to use an appliance cord, (no smaller than 14 gauge - 3 wire cord). This way you have your disconnecting means and a proper grounded path.

Hope this helps!! Good Luck

Side Note - After being questioned, I have verified the information that I have given with my hubby and a Master electrician. The Water hose analogy IS CORRECT. Wattage is pressure, Voltage is speed. Hence the Water hose analogy.

Dishwasher Electrical Connection

Back to basics:

The dishwasher should be on a separate designated circuit.

As such there should be an un- interrupted feed from the panel box to the dw's junction box

If that is not the case you absolutely must run a new circuit

To the matter of the armoured cable/bx

The system of metal boxes connected to metal clad cable using metal connectors does work providing:

That the connectors are securely anchored to the boxes - they have to be really tight

That the cable is securely anchored to the connectors using a set screw .

It is a case of mechanical intergrity resulting in electrical integrity.

In that system ,to ground your dishwasher you would secure a ground wire to the JB-and they make many devices just for that purpose- and then splice the ground wire from the dw

Where the metal box, cable, connector system fails is when the connector is improperly installed in the box and / and or when the cable is installed in the connector.The result is a break in the return path to ground -not safe.

I'll bet the guy who installed the dishwasher used the "Flexible Armore Sheathing " as the ground wire.

If the recepticle in your cabinet is grounded, than buy a 3 conductor piece of wire (white/black/green). make sure the piece is long enough so the green (ground wire) can reach some part of the dishwasher either the motor or some metal part on the dishwasher.

Watts Up Doc??

Tiffany had better talk to her hubby.

The water hose analogy is great except water pressure is like VOLTS, and water flowing is like AMPS. Watts is volts times amps

Look at your dishwasher's name and model plate. It will tell you the voltage that is required to run the appliance. In North America it will be either 120 or 240 volts. I suspect it will be 120 volts which means a neutral and hot wire. Neutral is by code white. If there is no green or bare copper wire in the service box, then the armoured cable sheath is being used as a ground. Not the best way to do it and not to code. To hook up the dishwasher, use three wire (white, black and ground) hook the ground to the service box. the best solution would be to replace the feed from the breaker panel.

a dishwasher or any major water appliance (refrigerator,jacuzzi,large fish tank,washer-dryer combo) should be wired as a direct home run to the circuit breaker/fuse box and i would recommend a gfi breaker at the main box. as long as your lines in the wall are bx cable (metal flex) your armored sheath should pick up the ground at the outlet. if you are not comfortable with this simply insert an additional wire (should be green) in the existing sheath and attach it to the outlet box. ps-amperage is current, it is the push behind the voltage. a person may survive getting hit with thousands of volts provided the current is minimal. the third rail of the subway is only 600 volts, but the current will fry you.

In the little box on the bottom of the D/W where the black and white wires are there should be a green screw to land the ground on. The screw may have fallen out. Any screw that will tighten down will be sufficient. Lacking a pre-threaded hole at that box, use a self tapping screw. It doesn't meet the "letter" of the Code, but it will meet the "intention" of the Code, which is to provide an alternate return path to the panel.