Im looking at a clothes dryer outlet, what prong is hot and which is neutral?

nokiacommi

Junior Member
Jul 11, 2003
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im trying to connect my SGI origin 2000 to my dryer outlet(it requires 250V). I just need to know which prong (left or right looking at the 3 prong outlet from the front) is hot and which is neutral. Right now i only know what the ground is.
 
Jan 18, 2001
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they sell these cheap little testers that will tell you. You can't trust that the outlet is wired correctly so it doesn't do any good to assume there is a standard.
 

Encryptic

Diamond Member
May 21, 2003
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Originally posted by: nokiacommi
if i connect it wrong will it mess up my computer or does it not matter?

I don't think it would affect anything unless your computer was plugged into the same outlet (same circuit?). But to be safe, maybe just unplug the computer or be sure you've got a good surge protector attached.

::shrug::
 

nokiacommi

Junior Member
Jul 11, 2003
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the power is AC current, so does the polarity matter? Also, i cant find a surge protector for 250V connection
 

Armitage

Banned
Feb 23, 2001
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Originally posted by: conjur
Left.


bzzzzzzttt..


(No, right!)


both ... a 220V outlet has two hot wires, and a single ground. Pull the face off the outlet, the ground wire should be white, and the hot wires red & black. If you have the right connector on it, it should only fit one way. If you don't have the right connector, you should question if you have the right amperage on the outlet.
 

BillGates

Diamond Member
Nov 30, 2001
7,388
2
81
Originally posted by: ergeorge
Originally posted by: conjur
Left.


bzzzzzzttt..


(No, right!)


both ... a 220V outlet has two hot wires, and a single ground. Pull the face off the outlet, the ground wire should be white, and the hot wires red & black. If you have the right connector on it, it should only fit one way. If you don't have the right connector, you should question if you have the right amperage on the outlet.

Bravo - we get one good answer!
 

nokiacommi

Junior Member
Jul 11, 2003
14
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so the two hot wires are the same and doesnt matter if reversed? Im using a crappy dryer cord that fits properly in the outlet but doesnt tell you what wire is connected to what prong execpt it only tells u ground and doesnt tell you the which hot wire is connected to what.
 

Analog

Lifer
Jan 7, 2002
12,755
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Originally posted by: nokiacommi
the power is AC current, so does the polarity matter? Also, i cant find a surge protector for 250V connection

polarity matters, because neutral and ground are at the same potential. Reversing neutral and hot could be a safety concern.
 

phpdog

Senior member
Jun 26, 2003
609
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use some other appliance thats not as expensive to test it e.g. lamp , iron , hovver
 

nokiacommi

Junior Member
Jul 11, 2003
14
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my dryer works fine and has been working for years on it.....im only going to use the SGI on the outlet for a short time.
 

Armitage

Banned
Feb 23, 2001
8,086
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which hot wire is which shouldn't matter, same voltage, just 180 degrees out of phase with each other. That's why you can get by with a single neutral.
But, IANAE.
 

nokiacommi

Junior Member
Jul 11, 2003
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but arent some two prong plugs polarized? If the connections r reversed, would that mean my dryer would not work on the outlet?
 

Armitage

Banned
Feb 23, 2001
8,086
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Yea, I think it would likely be a Bad Idea to connect the neutral to a hot wire in a 220 outlet. But the plug should make that impossible. You should only be able to plug it in one way.
 

NogginBoink

Diamond Member
Feb 17, 2002
5,322
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Originally posted by: nokiacommi
but arent some two prong plugs polarized? If the connections r reversed, would that mean my dryer would not work on the outlet?

110V outlets are polarized with respect to ground.

On a 220/240V outlet, both hot wires are hot with respect to neutral, so there's no such thing as polarizing the plug.

Get out a voltmeter.

Between left and ground, you should measure 120V.
Between right and ground, you should measure 120V.
Between left and right, you should measure 240V.

If you get those voltages, plug in your dryer and finish your laundry; you're good to go.
 

etech

Lifer
Oct 9, 1999
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Originally posted by: nokiacommi
im trying to connect my SGI origin 2000 to my dryer outlet(it requires 250V). I just need to know which prong (left or right looking at the 3 prong outlet from the front) is hot and which is neutral. Right now i only know what the ground is.

What you are calling ground is actually a neutral. As has been stated above the other two wires are both hot(120 VAC).

You could use either one and the neutral but it really isn't that great of an idea. The dryer outlet will be on a high amp breaker so you won't have protection for your equipment or the wires you are running.

Are you going to use the outlet for a dryer anymore?
If not you could install a new breaker and use the current wire. You would need to wire the ground and properly color code it in the breaker box. A piece of green/yellow stripe heat shrink tubing.

There are other considerations such as the size of the wire fitting into the new outlet but if you don't know that both wires are hot on a 240v outlet I would suggest calling an electrician.

 

Armitage

Banned
Feb 23, 2001
8,086
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Originally posted by: etech
Originally posted by: nokiacommi
im trying to connect my SGI origin 2000 to my dryer outlet(it requires 250V). I just need to know which prong (left or right looking at the 3 prong outlet from the front) is hot and which is neutral. Right now i only know what the ground is.

What you are calling ground is actually a neutral. As has been stated above the other two wires are both hot(120 VAC).

You could use either one and the neutral but it really isn't that great of an idea. The dryer outlet will be on a high amp breaker so you won't have protection for your equipment or the wires you are running.

Actually, he needs both of em ... that Origin drinks 220V straight up.

Are you going to use the outlet for a dryer anymore?

What I'm guessing from this thread so far is that hte plug on the Origin doesn't match the dryer outlet, despite being 220V, and he's wondering how to make it work. Probably a different amperage outlet, which will use a different style plug. I'd take a look at ours next door, but it would probably piss some people off if I went over and unplugged it :D

If not you could install a new breaker and use the current wire. You would need to wire the ground and properly color code it in the breaker box. A piece of green/yellow stripe heat shrink tubing.

There are other considerations such as the size of the wire fitting into the new outlet but if you don't know that both wires are hot on a 240v outlet I would suggest calling an electrician.

 

silverpig

Lifer
Jul 29, 2001
27,703
12
81
Don't mess with electricity unless you KNOW what you're doing.

240 V has two hot wires (240V potential difference between them), while 120V has one hot wire (120V potential difference between hot and neutral).

Having polarized plugs is a safety feature. It just forces the switch on the appliance to come before the actual appliance so you don't fry yourself if you leave it plugged in while working on it open. Diagram:

On 120V plugs you have a 120V hot and a neutral wire. The appliance has a switch and a load (toaster element for example). A polarized appliance forces the switch to be between the hot wire and the load instead of the neutral wire and the load.


Hot - switch - load - neutral

That is forced on a polarized plug as opposed to hot - load - switch - neutral.

In the second example you can see that if you have the switch off, and jam your knife in the toaster, you can get a shock as you will be touching a hot source. In the first one, as long as the switch is off, you can jam your knife in and not get a shock.

I'd just unplug it first myself... just to be sure :)
 

etech

Lifer
Oct 9, 1999
10,597
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Originally posted by: ergeorge
Originally posted by: etech
Originally posted by: nokiacommi
im trying to connect my SGI origin 2000 to my dryer outlet(it requires 250V). I just need to know which prong (left or right looking at the 3 prong outlet from the front) is hot and which is neutral. Right now i only know what the ground is.

What you are calling ground is actually a neutral. As has been stated above the other two wires are both hot(120 VAC).

You could use either one and the neutral but it really isn't that great of an idea. The dryer outlet will be on a high amp breaker so you won't have protection for your equipment or the wires you are running.

Actually, he needs both of em ... that Origin drinks 220V straight up.

Are you going to use the outlet for a dryer anymore?

What I'm guessing from this thread so far is that hte plug on the Origin doesn't match the dryer outlet, despite being 220V, and he's wondering how to make it work. Probably a different amperage outlet, which will use a different style plug. I'd take a look at ours next door, but it would probably piss some people off if I went over and unplugged it :D

If not you could install a new breaker and use the current wire. You would need to wire the ground and properly color code it in the breaker box. A piece of green/yellow stripe heat shrink tubing.

There are other considerations such as the size of the wire fitting into the new outlet but if you don't know that both wires are hot on a 240v outlet I would suggest calling an electrician.


I'll admit I hadn't looked up the specs of the Origin originally and just assumed that it took 120 VAC.

SGI? 2200, SGI? 2400, SGI? 2800

It's not clear that it takes dual phase from that sheet. The rack takes single phase. The plate on the computer should detail its requirements.
 

AlienCraft

Lifer
Nov 23, 2002
10,539
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Originally posted by: nokiacommi
im trying to connect my SGI origin 2000 to my dryer outlet(it requires 250V). I just need to know which prong (left or right looking at the 3 prong outlet from the front) is hot and which is neutral. Right now i only know what the ground is.
UK 220v is different from USA 220v dryer outlet.
We (the US) make 220v (240v actually) by adding two 120v leads at 180* opposite phase, relative to GROUND/ Neutral, which we bond together at the service entrance. This renders NEUTRAL electrically equal to GROUND (EARTH). This makes for 240v in the dryer motor.
You need 240v on one lead with a NEUTRAL and GROUND. This can only come from a transformer taking 120v and converting to 240v.
An electrical supply house / contractor can help you, or maybe a travel adaptor/ transformer kit.

Good luck.
Try Partsexpress.com or Sharperimage.com
edit: The PDF that Etech provided calls for 220v single phase for the rack. You need one lead with 220v on it. The dual voltage supply rating on the desktop would also lead one to assume that one lead has between 110 and 220v AC (relative) and that the device will work in that range.

 

Analog

Lifer
Jan 7, 2002
12,755
3
0
Originally posted by: etech
Originally posted by: nokiacommi
im trying to connect my SGI origin 2000 to my dryer outlet(it requires 250V). I just need to know which prong (left or right looking at the 3 prong outlet from the front) is hot and which is neutral. Right now i only know what the ground is.

What you are calling ground is actually a neutral. As has been stated above the other two wires are both hot(120 VAC).

You could use either one and the neutral but it really isn't that great of an idea. The dryer outlet will be on a high amp breaker so you won't have protection for your equipment or the wires you are running.

Are you going to use the outlet for a dryer anymore?
If not you could install a new breaker and use the current wire. You would need to wire the ground and properly color code it in the breaker box. A piece of green/yellow stripe heat shrink tubing.

There are other considerations such as the size of the wire fitting into the new outlet but if you don't know that both wires are hot on a 240v outlet I would suggest calling an electrician.

nicely put.