240 Volt wire?

Hi,
I have a wire that seems to have only to conductors in it. It's a gray wire in which the plastic sheath is tight over the wire. The two wires are about 1/4" apart. I'm not sure how to better describe it.
It seems to be connected to a double breaker and carrying 240V to the A/C unit. Does that make sense? I guess if the two wires are 120V out-of-phase then the AC current can just flow from one of the wires to the other?
I'm trying to make sense of this for my own education, but also wondering what kind of wire I would need (12/2?) to replace this one (it's routed stupidly).
Thanks,
Aaron
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
How many amps, the breaker? For 20 amps, use 12 ga, for 30 amps, use 10 ga.
I've seen 2 conductor (with ground) wire used. I've also seen 3 conductor used, so there is a neutral as well as a ground.
Yes, the two poles of the 220 volt are out of time with each other. Oddly, they call that single phase 220.
--
Christopher A. Young
Learn more about Jesus
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Stormin Mormon wrote:

Well, they call it single phase because it is -- it's derived from two taps from the same generation phase that are (as you say) lagged 180 degrees with respect to each other.
IOW, while the two are "out of phase" w/ each other, they are not delivered from separate wires from the generator only two different voltage taps. As an aside, three phase is separated by 120 degrees on each phase so the difference in voltage between any two of them is variable in time where as the two in single-phase 240V are mirror images of each other and the voltage magnitude is fixed w/ time (sin^2 + cos^2 = constant).
Potentially (so to speak :) ) cornfoozing as there are two uses of the word "phase", both of which are correct but refer to different quantities/properties--the generator phases and the phase shift between any two or three legs of the single- or three-phase power.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Correct.
Ummm... Not unless your two hot wires are 90 degrees out of phase and you're using 2 dimensional wire. The voltage magnitude is 2*v*sin(t). 3 phase is more interesting (something like v*sin(t)-v*sin(t+120deg)).
Maybe you're remembering some current X magnetic field vector from a previous life?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Larry The Snake Guy wrote:

No, just an unfortunate ill-considered (or, more correctly, really not at all considered) attempt at a mixed metaphor...which while true geometrically, has nothing to do w/ the voltage... :(
Thanks for bringing it to everybody's attention... :) (Not that shouldn't have corrected the factual blooper)
--
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
dpb wrote:

The two lines are indeed in phase with each other. They also are not derived from different voltage taps, they are the connections to the full 240V winding on the distribution transformer, the "neutral" is a center tap in those windings. When looking at them relative to the center tap neutral they will appear to be opposite polarity or 180 out of phase.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

As posted: The question begs some very basic information.
Do hope that what is is described is not some sort of lash-up, perhaps using some sort of lamp wiring or portable extension cord????? In which case it a) May not be safe b) Not of sufficient size c) Not meet insurance standards (Liability?) or electrical codes.
1) The size of wire depends on the load to be carried. In North America typical are: #14 AWG 15 amps. Typically used for lighting circuits. #12 AWG 20 amps. Often/sometimes for duplex wall outlets etc. #10 AWG 30 amps. Typically for a clothes dryer and/or electric hot water tank circuit. Most wires (if they meet code) are rated for either 300 or 600 volts. Wiring may have either two insulated conductors plus ground wire. 2) The circuit breaker must be sized to the gauge of wire. As per above wire rating; do not exceed. The circuit breaker protects the wiring and anything connected to that circuit. For example do not connect say 14 AWG to a 20 amp breaker. And/or do not 'extend', say, an existing #12 AWG circuit using a lesser (higher numbered) gauge wire such as #14. 3) A typical continuous maximum load is 80% of the rated capacity. So, for example a 20 amp circuit is normally happy carrying some 15 to 16 amps. Regarding 220 versus 110 (sometimes it's 230 and 115 and sometimes again it's 240 vs. 120) but the principal, in domestic situations, but not industrial or commercial applications where there may be 208 volts/ 347 volts etc. is the same. Have emailed the OP directly with a suggestion as to how to recognise a domestic SINGLE PHASE 110/220 volt service.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I would look again to make sure there is not a ground in there. Is this an external ac compressor? Many ac's use only 240 and only need 2 hots and a ground. I've never seen one that didn't call for a ground though. You can replace it with the appropriate guage 12/2 or 10/2 with ground. It's ok if one wire is white and the other black. Some electricians will wrap a piece of black tape on the white wire near the ends so that it is obvious it is a also a hot. If the ground is missing then you should correct that situation. If you can not tell what size it is then locate the amperage on a tag on the ac and estimate the run length. Lots of resources on the net will calculate the correct wire size for you. If it is routed stupidly will you have enough wire to change the route if you just disconnect one end and re- route it?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Is there a ground wire at all? I know UF cable is gray (well the sheathing is). Example:
http://electrical.hardwarestore.com/14-48-building-wire-uf/10-2-uf-with-x-25%27%27-building-wire--667888.aspxYou have to look at the breaker that it is hooked up too. Some units onlyrequire a 30 amp breaker in which case you would use 10/2 with ground or10/3 with ground if for some reason you need the neutral. If you are goingto replace it, then maybe think about setting a disconnect like this:http://www.lowes.com/lowes/lkn?action=productDetail&productId550-82364-DP221RP&lpage=noneand get one of these and use #10 thhn wire inside to go from the box to theAC unit (look at the picture on the bag):http://www.lowes.com/lowes/lkn?action=productDetail&productIds209-223-150DRB&lpage=noneOf course this is just an example for a 30 Amp system.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

http://electrical.hardwarestore.com/14-48-building-wire-uf/10-2-uf-with-x-25%27%27-building-wire--667888.aspx
You have to look at the breaker that it is hooked up too. Some units onlyrequire a 30 amp breaker in which case you would use 10/2 with ground or10/3 with ground if for some reason you need the neutral. If you are goingto replace it, then maybe think about setting a disconnect like this:
http://www.lowes.com/lowes/lkn?action=productDetail&productId550-82364-DP221RP&lpage=none .
and get one of these and use #10 thhn wire inside to go from the box to theAC unit (look at the picture on the bag): .
http://www.lowes.com/lowes/lkn?action=productDetail&productIds209-223-150DRB&lpage=none .
Of course this is just an example for a 30 Amp system.

sorry about the links usually it works. anyway I would get a 30A disconnect, some THHN #10, and some Carflex and connectors for the outside.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Aaron, you need to do a tad more investigating before asking questions. Your description sounds like U.F. cable, but if you look at the jacket, it will have it's type and size either printed or embossed on it.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Site Timeline

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.