Grounding for Three-Prong 220v Outlet

[PeruvianHighlander]

I need to add a three-prong 220 volt outlet for a dryer. I did a lot of research to figure out what I needed, so I bought an outlet, 10-3 cable, and a bi-pole 30 Amp breaker. Once I got it home, I opened up the outlet and it has only three screws: one silver for the nuetral wire, and two copper for the hot wires, but no green one for the ground!
On the back of the bag it says this:
CAUTION: This device is not for grounding use. Connect only to non-grounding circuits unless it is to be used for range or clothes dryer in accordance with the National Electrical Code.

I am using this for a dryer, so it should be grounded, correct? Did I get the wrong outlet? This was the only outlet they had at Lowe's:

http://www.lowes.com/lowes/lkn?action=productList&N=0&Ntk=i_products&Ntt=dryer%20outlet

It is the middle item in the link above. Please help me if you can tell me how to wire this outlet, or if I need something different. Thank you.

[Snoonyb]

Does your existing appliance cord mate to this recepticle?

[kactuskid]

All new dryer circuits MUST be of the grounded type no matter what your existing dryer's cord configuration is. The proper cable MUST contain a ground wire so I hope you really purchased 10-3/G. The 3 slot receptacle you purchased is the wrong one.

You need to buy a NEMA 14-30 receptacle that has 4 slots in it like this one:

http://www.foxelectricsupply.com/con...ductNo=EAG1225

If Lowes doesn't carry it then go to a good hardware store like Ace or True Value but per your link the PROPER one is on the far left.

Then use the following link to wire it up and also make sure you have a 4 prong cord connected to the back of the dryer.

http://www.selfhelpandmore.com/switc...ryer/index.htm

[PeruvianHighlander]

Thank you for your responses

To answer SnoonyB's question: yes, my dryer's power cord currently has three-prong configuration that fits the outlet I purchased.

Lowe's has several of the four-prong outlets, but I did not purchase them because my dryer has a three-prong configuration. I saw many posts explaining the process of replacing the cord in the dryer and I think I can take care of that. I did buy 10-3 (Black, White, Red, and ground). Thank you for all of your help. I guess my only questions, are: why would they make ungrounded outlets in the first place (safety)? and why do hardware stores still sell them? Regardless, thank you very much for your help.

PeruvianHighlander

[kactuskid]

why would they make ungrounded outlets in the first place (safety)? and why do hardware stores still sell them?

Three prong ungrounded receptacles are still made and sold to replace existing broken ones. The old code allowed the circuit neutral wire to also serve as the equipment grounding conductor. These old existing circuits are allowed to be used but cannot be extended. So if one exist in a house and a new dryer is bought that has a 4 prong cord, the dryers cord is allowed to be changed to a 3 prong one to utilize the existing circuit.

But, the code states that any NEW dryer or range circuits MUST BE grounded and therefore require the 4 prong receptacles. This is what you want anyhow cause YES, it is safer than the older 3 prong types.

If you need to also change out your existing 3 prong cord to a 4 prong make sure you remove the existing ground strap that connects the circuit neutral to the dryers frame and that the ground on your 4 prong cord is then connected to the dryers frame. This is all shown and explained in the link above.