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I have a new dryer, and I have a 3-prong outlet (NEMA 10-30). The written instructions and the video instructions for this model contradict each other. Internet research has only confused me more. Looking for a clear, definitive answer... Do I install the wires like this (pic 1): enter image description here

...where the white wire is left connected to the chassis (this is what the manufacturer video says, and what most other videos I’ve found say)

OR do I do it like this (pic 2): enter image description here

...where I connect the white wire to the middle (neutral) terminal? This is what some internet things say, and this is also what the written instructions say, with an additional claim that I need an external ground wire connected to the chassis and then imaginably, a ground.

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    The "definitively correct way" is to run a ground wire to the socket location (which you can, without needing to follow or replace the present Hot, Hot Neutral wiring, since the 2014 code cycle IIRC) and toss that 3-wire socket in the trash and use a 4-wire cord to a 4-wire plug to a correctly wired 4-wire socket.
    – Ecnerwal
    Aug 23 '20 at 1:29
  • I have an electrician coming to do some other work on our home... is swapping a 3-prong outlet to a 4-prong outlet a huge endeavor? Does it require extensive rewiring? If not, I would just ask them to swap this out while they’re here.
    – admbmb
    Aug 23 '20 at 1:32
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    I would agree with @ecnerwal but you are not required to update wiring ,, knob and tube is still code compliant with a 3 wire connection I would recommend a connection from the metal water pipe to the frame green screw totally code compliant today.
    – Ed Beal
    Aug 23 '20 at 1:36
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    Yes any part of the metal water piping system should be grounded. For many years water piping was the only ground. As long as it is I contact with earth for 10’ that would still be a code allowed grounding electrode. Because plastic plumbing is replacing metal it is not as popular as a grounding electrode but is still allowed in the 2020 code and the only way to make a 3 wire connection safe (this actually turns it into a 4 wire).
    – Ed Beal
    Aug 23 '20 at 15:31
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    @HotLicks -- can't use the water pipe for this, you'd have to run back to the panel, to a grounding electrode conductor, or to a properly grounded 30A+ circuit Aug 23 '20 at 18:18
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There is no way to make a 3-wire connection safe.

It's only legal on a legacy basis, with certain cable types because the appliance industry complained and moaned that they'd lose appliance sales if it was outlawed.

What they are actually doing is connecting chassis to the live neutral. The concept is that neutral is supposed to be safe... as long as there aren't any loose connections... and loose connections are unlikely since these plugs and wiring are rarely disturbed. Uh huh.

So it is leeeegal to jumper the appliance chassis to the neutral wire and then call it a day. Would I do it? Heck no!

However in my experience many installations either have a 3-wire receptacle needlessly because they actually do have ground behind the receptacle... or they are using a cable type that was always illegal (/2 + ground NM or UF).

You are really, really better off upgrading to 4-prong receptacle and plug ASAP. That will give you a separate neutral and ground.

If your installation is old and uses a legal cable type (/3 noground or SE), then it's legal to retrofit a ground from the socket to anywhere that has a #10 or larger ground back to the panel - water heater, grounding electrode wires, any metal conduit, or back to the panel.

If it is infeasible to retrofit a ground, you can change the receptacle to 4-prong anyway, wire the appliance for 4-prong anyway (meaning: isolate neutral from ground, very important!), and then use a 2-pole GFCI breaker to feed it. This is labeled "GFCI Protected / No Equipment Ground".

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    Why bother to change to a 4-wire receptacle if the circuit is GFCI with no equipment ground? Aug 23 '20 at 7:49
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    because touching a chassis on a live neutral where an asymmetric load or other significant phase fault occur, will kill you.
    – dlatikay
    Aug 23 '20 at 11:33
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    @batp because a 3-wire cord requires jumpering neutral to chassis. Bootlegging utterly defeats the protection of the GFCI. Aug 23 '20 at 19:09
  • What about this: leave the outlet as is (3-prong), use a 3-prong dryer cord, leave the ground terminal on the dryer unconnected, and use a 2-pole gfci breaker? I believe this is what @batsplat is asking. And I don't see anything wrong with that approach.
    – Haozhun
    Aug 24 '20 at 8:57
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    @Haozhun That's fine if you live on a desert island and have total control of everything. But you can't do that in a society where different people's actions interact. Suppose you get a better dryer, installer goes "oh ok 3-prong cord, jumper ground". You miss it. You sell the house. Etc. 1000 things can happen. It's the same basic reason they require generator interlocks and not just some smart guy knowing not to have 2 breakers on at once. Aug 26 '20 at 4:26
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You do it like in picture one. The neutral is grounded to the cabinet with the green screw.

If you had a four wire outlet, then the white wire to the cabinet would be moved to the center post like in your picture 2 and the green ground wire from your four wire plug cord would go to the cabinet with the green screw. If I were you, I'd check to see if you have four wires available in your outlet box and think about replacing the three prong cord and outlet with a four prong setup. It's a nice safety feature.

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  • But doesn’t the connection to the chassis defeat the purpose? If current needs to be sent through that ground because of some fault (it’s actually called a neutral ground) wouldn’t that current end up on the chassis which is what I don’t want?
    – admbmb
    Aug 23 '20 at 1:54
  • @admbmb No, you want the chassis grounded. if a hot leg were to break off and hit the chassis, you want it grounded so it trips the breaker. Otherwise you end up with a hot chassis and someone touches it and turns on the water.. bye bye..
    – JACK
    Aug 23 '20 at 1:59
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    @admbmb There's no such thing as a "neutral ground". Neutral is not ground. In a 3-prong/wire connection, the third wire is neutral and there is no ground. The instructions are telling you to bootleg chassis ground off neutral. Since neutral can float up to line voltage merely from a loose connection, this is just as dangerous as it sounds. Aug 23 '20 at 5:10
  • @Harper-ReinstateMonica So this is what’s confusing. I have people telling me that I should leave that wire bonded to the chassis, and others (like you) saying that that’s dangerous. That’s what I’m trying to figure out.
    – admbmb
    Aug 23 '20 at 5:13
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    @admbmb As i mentioned in my answer, the four wire is the way to go but the three wire, picture 1, is legal and the way the manufacturer stated to do it. Yes, as Harper stated, the neutral can rise to line voltage but it can also stay at zero voltage protecting you from a line fault to the cabinet. Your question was which picture to follow for your power supply and that's picture 1. There are thousands hooked up like this. The safety issues should be another question.
    – JACK
    Aug 23 '20 at 12:35
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There is no "definitive" answer, or standard hookup; You have to follow the manufacturer's instructions but the manufacturer has dropped the ball if they have contradictory instructions out there.

That said, you will want picture two. BUT, please make sure the spade terminal is straight and the bare metal is well clear of the terminals on the left and right, you do not want to create a short.

There is a simple principle that determines how you'll make the connections. When 240/120V appliances are connected without the fourth equipment grounding conductor, the connections are done such that the dryer's metal frame is bonded to the neutral (white) wire. That's what the jumper is doing.

The exact details of the connections will differ from appliance to appliance, it will depend on how the terminal block inside the dryer is wired. In the picture below, there is a ground strap that you remove when you have four wires.

three wire and four wire appliance connections

Upgrading to a four-wire circuit would make this safer, but it's very common on older homes and not a major hazard. Alternately adding GFCI protection to the circuit by replacing the breaker in the panel would make it safer and usually dryers are pretty GFCI compatible.

The picture is from

http://www.adamselectric.coop/wp-content/uploads/2015/02/Bonding-Frames-of-Major-Appliances.pdf

where you can read a more detailed explanation.

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  • I do not have a ground strap on my unit and my outlet is NEMA 10-30, not 10-50. Other answers indicated fairly clearly that picture 1 is the way to do it, although still not technically safe.
    – admbmb
    Aug 23 '20 at 15:19
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    The "ground strap" shown in this diagram is the white wire in your dryer that is connected to the ground screw. The picture shown for a 10-50 is functionally the same as the 30 amp 10-30 version. Aug 23 '20 at 15:21
  • @NoSparksPlease So then how do you reconcile your answer with the others? Are the others wrong?
    – admbmb
    Aug 23 '20 at 17:10
  • Based on the OP's supply, it would be picture 1. Definitely.
    – JACK
    Aug 23 '20 at 18:28
  • Not sure what I am to reconcile, if the question is safety, safety is always a compromise. There are lots of things they could require that would make appliances safer. GFCI's, larger wire, built in smoke detectors, audible heat alarms, narrower fuse/breaker designations all could provide more safety. The NFPA (the writers of the NEC) and UL consider a 3 wire safe enough to allow appliances to be sold allowing a 3 wire configuration. Some here disagree. I agree 4 wire is safer, the experts aren't requiring it at this time. Aug 23 '20 at 20:33
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This is where you need to look at the MFG requirements. Notice the 2 larger wires on the outside those are normally the hots the center wire is the neutral for 3 wire without ground because the heating element is 220-240 and the motor that turns the drum is usually 120v and the controls are 120v in these cases the best option is a grounding connection from the metal water pipe to the frame of the dryer . I can say this because by the time plastic plumbing became the norm 4 wire was code.

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  • Not sure why the down votes but connecting the chassis to a metal water pipe is recommended but all the non electricians don’t understand that. And this was the standard for decades .
    – Ed Beal
    Aug 23 '20 at 15:23
  • I think it’s because this isn’t a direct “answer” specifically, just some additional information. While not wrong, I suspect that’s the reason.
    – admbmb
    Aug 23 '20 at 17:11
  • It states where the neutral is and how to connect the ground.
    – Ed Beal
    Aug 23 '20 at 17:36
  • The DV doesn't make sense and I got one too..... go figure.... +1
    – JACK
    Aug 23 '20 at 17:53

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