Why does 220 has no neutral

Reply

  #1  
Old 12-07-05, 04:20 PM
Jeff Walin
Visiting Guest
Posts: n/a
Why does 220 has no neutral

Why does a 20A 220v 3 pronged outlet (with sideways T shaped neutral) have two hots and no neutral. If I had to guess, I would say that the wires allow the AC to "alternate" between the two hot wires, thus you have current, but it's confusing. Where can I read more about this?

And is it safe to plug everything into these outlets, like a surge protector attached to computer, printer, monitor... The surge protector says on the bottom 15Amp I think. I don't expect to plug anything but the computer through the surge protector.
 
Sponsored Links
  #2  
Old 12-07-05, 05:07 PM
Member
Join Date: Sep 2002
Location: welland ontario
Posts: 5,663
Neutral is only required when 120 volts is needed. It is only safe to plug in 240 volt devices.

Found these links that might be useful.

http://ourworld.compuserve.com/homep...mith/basic.htm

http://members.tripod.com/~masterslic/basics.html

http://www.leonics.com/html/en/about..._knowledge.php
 
  #3  
Old 12-07-05, 05:44 PM
Member
Join Date: Sep 2000
Location: United States
Posts: 18,497
A circuit, no matter how many volts it is, only needs two wires: one for the electrons to flow out on and one for them to flow back on. The electrons don't care one bit what words we use to describe these two wires. Terms like "hot" and "neutral" are just words. The electrons are just as happy to flow on two wires that we call "hot" and "hot".
 
  #4  
Old 12-07-05, 08:42 PM
Jeff Walin
Visiting Guest
Posts: n/a
Thanks for the great links. I have more questions about what you said here:

"It is only safe to plug in 240 volt devices."

When you say "devices," that doesn't sound like you mean surge protectors or extension chords?

I have an air conditioner that can only be plugged into this type of outlet (outlets with a horizontal line coming out of the left of the vertical "neutral" slot,) but out side of that, the outlet is physically designed with backward compatibility with all 15Amp 110 polarized plugs, grounded or not, so are you telling me that I can't plug a computer, printer, scanner, monitor, hair drier, space heater?

What will happen if I do? And why would they make these outlets 100% compatible with all 15A 120v polarized appliances? Doesn't the code recommend these outlets in bathrooms and kitchens? Who is going to plug an AC in a bathroom, and I didn't see a horizontal notch on my fridge?
 
  #5  
Old 12-07-05, 09:31 PM
Member
Join Date: Nov 2004
Location: CA
Posts: 2,041
Be careful about the difference between "no neutral" and "no ground"


An appliance like a water heater needs no neutral whatsoever. 240 volts exist between the red and black leads. The neutral connector in your house is connected to the center tap of the feeding transformer, So either hot leads will have 120 volts to neutral.

So, a water heater will have red, black, and green or bare ground, but no neutral. There is no place on this circuit to pick up 120 volts.

An older receptacle ( 3 wire ) for a range or dryer has red , black , and white neutral. The neutral allows the appliance to have 120 volts for a motor, control circuits, etc. and 240 for the big heat. At the time, they were allowed to connect the white to chassis and it served as the ground, but this was not completely safe. There is no way to pick up a 120 volt outlet on this circuit , because there is NO GROUND.
 
  #6  
Old 12-07-05, 10:38 PM
Jeff Walin
Visiting Guest
Posts: n/a
I'm looking at the outlets here:

http://www.leviton.com/sections/techsupp/nema.htm

and now I'm thinking that I'm confused.

Perhaps I looked in a book and got confused by the illustration and I'm thinking that 5-20R is wired like 6-20R.

So I guess I'm really talking about 125V 5-20R

So maybe there is a neutral wire after all, the only difference would be the 12 gauge wire, 20a breaker, and 20a outlet. Would that be correct? So this could be used with all the appliances I'm currently using, Right? I was worried for a little bit there.

Sorry for the confusion, but I needed that answer any way.
 
  #7  
Old 12-08-05, 05:24 AM
Member
Join Date: Dec 2000
Posts: 510
What you are describing is a 120V 20A receptacle, not a 220V receptacle. As you can see from the diagram you linked to, the 5-20R can accept either a 5-15P or a 5-20P, but a 5-15R (120V 15A receptacle) can only accept a 5-15P. This is because it is acceptable to plug a 15A device into a 20A circuit, but it is not acceptable to plug a 20A device into a 15A circuit.

But it sounds like you figured all this out...
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes