20 amp AC unit – what size breaker
Brian
| Posted in Energy, Heating & Insulation on
Wiring for a new AC window unit – 220v, unit says it is 20 amps (1,020 watts). Can I use 12/2 and a 20 amp breaker, or do I have to go to 10/2 and 30 amps?
I figure there must be some loss figured in somewhere ~40′ of wire to the box.
The unit:
http://www.samsclub.com/shopping/navigate.do?catg=535&item=328563&prDeTab=2&pCatg=4777#A
Treat every person you meet like you will know them the rest of your life – you just might!
Replies
Something is wrong here. If it is 1020 watts, it should be 4.7 amps. It should be fine with a 20a breaker, even if it is 20 amps. The typical amps at 220 for this size AC is 12-13 amps.
Wait - where are you? I know the electricians here are going to chime in and say you can't use ANY -2 for 220V, and that you have to use multiple redundant multiplexed isolated discombobulated neutrals and grounds - seven of each, IIRC, is what they recommend today.
:-)
Forrest
You are right.There is no 220 volt service available in the US. Must be some furin country.
>>There is no 220 volt service available in the US. Must be some furin country
Almost all residential service is 220 (nominal) with a few very rare 110 services left over from the early part of the 20th century which haven't been upgraded.
Residential service is 2 110 "legs" and a neutral.
You are a home inspector.If you measure 110 or 220 on a house you are inspecting you should be reporting it as a problem.
Nah, the meter you're using isn't that accurate (if you're a home inspector).
If Tyranny and Oppression come to this land, it will be in the guise of fighting a foreign enemy. --James Madison
>>Nah, the meter you're using isn't that accurate (if you're a home inspector).
When needed, I measure electric the old fashioned way: a wet floor and a finish nail <G>
I don't actually meter electric, but my CO meter is as accurate as any carried by HVAC folks and more accurate than that carried by many. (ANd many don't carry or know how to use any CO meter)
>>You are a home inspector.
>>If you measure 110 or 220 on a house you are inspecting you should be reporting it as a problem.
I don't meter stuff like that.
Those are nominal figures; should I be calling out 2xs that aren't really 2x whatever as a problem?
No, the NOMINAL is 120/240.110/220 would be well below normal.Don't know when 120 was standardized, but looking at the labels on some old motors I think taht it was before the 50's.
No, the NOMINAL is 120/240.
As usual, Bill is correct. ;)
In the U.S., the standard for voltage delivery is ANSI C.84.1, American National Standard for Electric Power Systems and Equipment - Voltage Ratings (60 Hertz). It defines the nominal value for volt at the service entrance of 120Vand 240V.
Two tolerance ranges are defined. "Range A" is the normal circumstance, and excursions outside this range should be infrequent. The tolerance on the service voltage is +/-5%, or 114V-126V for the 120V voltage.
"Range B" conditions are supposed to be limited in extent, frequency, and duration. If they occur on a sustained basis, the utility is supposed to take corrective measures. The tolerance is +6%, -8%. So 110V is just outside even the Range B area, and would be considered abnormal.
This is an important standard, as designers of "utilization equipment" (things that use electricity) must know what range of voltages their designs will encounter in the field. Equipment should be designed to give acceptable performance over the Range B tolerances, taking into account the additional voltage drop due to feeder and branch circuit losses.
It's these additional losses that explain why the nominal nameplate voltage ratings for motors and appliances are 115V/230V. NEMA standards say the equipment should operate satisfactorily over a +/-10% range. In other words (103.5-126.5)V/(207-253)V. The NEC recommends limiting total feeder plus branch losses to 5%; combine this with the Range B tolerances and you have a +6%, -13% range, or (104.4-127.2)V/(208.9-254.4)V. That matches up with the NEMA ranges pretty well. So assuming everybody follows the recommended standards, everyone should be happy, and nobody gets hurt.
Further, some equipment is designed to function satisfactorarily on either 240V nominal or 208V nominal, so that two legs of a three-phase feed can be used.
If Tyranny and Oppression come to this land, it will be in the guise of fighting a foreign enemy. --James Madison
I asked over in the JLC electrical forum if anyone knew when 120/240 was standardized as the nominal supply voltage.The one response I got was from some one that had some old code books....The oldest code cycle in my library is the 1962 cycle.
I find in 220-3 (B) the third paragraph
“A three wire 115/230 volt branch circuit is the equivalent of two 115 volt receptacle branch circuit.”
Also in
220.7 Optional Calculation for One-Family Residence. For a One-Family residence served by a 115/230 volt. Three wire, 100 amp. or larger service…These same words can be found up till the 1975 cycle and the third paragraph was dropped from 220-3(b) but the Optional Calculation which has been moved to 220-30 still mentions the 115/230 voltage.I jump in cycles to the 1984 cycle for the first time a voltage is mentioned in;
220-1 Scope (second paragraph) Unless other voltages are specified, for purposes of comuting branch-circuit and feeder loads, nominal system voltages of 120, 120/240, 208Y/120, 240, 480Y/277, 480 and 600 volts shall be used.Leap again to the 1996 cycle and we find something moved and something was added.220-2 Unless other voltages are specified, for purposes of coumpting branch-circuit and feeder loads, nominal system voltages of 120, 120/240, 208Y/120, 240, 347, 480Y/277, 480, 600Y/347, and 600 volts shall be used.
(Did you notice the new voltage of 347?)In the 2005 cycle it moved again to 220.5 and again a change in the verbiage.The 2005 cycle freed us from the computer. Previous cycles of the NEC had mandated by the term “computed” that we use a computer but now mandates us to use a calculator as pointed out by the word “calculated” found in 220.5 of the 2005
220.5 Calculations. (A) Voltages. Unless other voltages are specified, for purposes of calculating branch-circuit and feeder loads, nominal system voltages of 120, 120/240, 208Y/120, 240, 347, 480Y/277, 480, 600Y/347, and 600 volts shall be used.And they are trying to convince me that technologies are growing at leaps and bounds. I threw all my calculators away when I learned how to install a program and now I have to regress to a calculator again. What’s next, slide rules?
__________________
Mike Whitt
Electrical Contractor/Instructor
Asheboro, North Carolina
And this is some of the things that I found from googling.have done some more research also. It appears that standardization on 120 was later than I thought. But I have not come up with anything more specific than what you have.I have two old motors that my dad had when he died in 1953.One is on a Craftsman drill press. It is a GE and in general appears the same as current motors. It is labeled 115. The other was off a DriverLine scroll saw that I thinks redates WWII. It was a Kenmore motor and the style "looks old". It is labeled 110v.Some other things that I found.http://www.practicalmachinist.com/cg...3;t=001629;p=0"Semantics.
There are 2 "voltages" to be concerned with. One is the "Distribution Voltage", meaning what the utility gives out; the other is the "Utilization Voltage" which is what the device or motor is designed to use. Because the US power "grid" as we know it now was originally a big bunch of unconnected separate producers, each producer had their own standards. Large ones early on such as New York, Chicago, Boston etc., were where the biggest market for electrical products were, so manufacturers tended to cater to them and their standards. This ultimately had the effect of driving other smaller utilities into conformance because their users sometimes found it difficult to find appliances and machinery that would work at odd voltages. 460 was chosen by NEMA (National Electrical Manufacturers Assoc.) as the compromise utilization Voltage because it was mid way between 440 and 480, and they also specify that motor HP and torque ratings would be based on a +-10% voltage level from there. So a 460V rated motor can tolerate any voltage from 414 to 506V. The same is true for 230V as the compromised Utilization Voltage, because motors can then tolerate from 207 to 253V, although most new motors are designed now to accept from 200-250V because of 208V systems. 115V is the compromise between 110 and 120V, although at that level you still see ratings all over the map because it really doesn't matter.If you pay attention, you won't see motors with nameplates that say 480V (unless they were specially wound for someone). You will however see VFDs that say 480V, because they are referring to the VFD's voltage tolerance, not the motor you connect to it. In a VFD, the output voltage can be lower than the input voltage, so you tell the VFD what the motor nameplate says anyway.If you have a 3 phase motor that says 440V or 220V on the nameplate, it was designed specifically for that voltage, which means it is pre-NEMA. That also means you don't necessarily know the voltage tolerance if it's not stamped on the nameplate, so be careful."http://www.listserve.com/archives/co.../msg00131.html"> Years ago in the US the normal residential mains voltage was stated to be
> 110 VAC and 220 VAC. With the various distribution systems being used,
> delta, wye, single phase and 3 phase, it has become more economical to
> derive voltages in our homes from the more popular and demanded 3 phase
> system, be they delta distribution or wye distribution system. Thus the
> nominal voltage became 115 and 230 and then later became 120 and 240.
> These of course are held to about +/- 10 percent tolerance or less.
> Additionally, in order to make up for loss in power distribution systems
> (among other reasons) around the country the power companies typically run
> the voltage on the high side. Thus we see values in the 125 to 128 range
> depending on load conditions on the system. I've seen as high as 260 here
> at the house. Lights are bright and the power amp really sings out some
> watts.
>
> Most of the Collins radio equipment and others for that matter, of 40+
> years
> ago, did consider that mains voltage would be a bit lower than it actually
> is today. Usually in most cases today a 10% increase for ICAS usage
> causes
> no concerns. Thus equipment rated, as my 516F-2 at 115 VAC, has no
> problem
> with today's 125 to 128 VAC mains. Neither does my 1938 Western Electric
> broadcast transmitter on which the cover plate is printed: "Mains voltage
> 220 VAC"."http://www.epanorama.net/links/wire_mains.html"It appears that the 120 were chosen somewhat arbitrarily. Edison came up with a high-resistance lamp filament he thought desirable to keep distribution losses down. The voltage of the original electrical systems were determined by thenumber of light bulbs in a string, obviously because at that time the only thing connected to the electrical system were light bulbs. So around 110V (110-120V) was chosen because it was a convenient number of lights. In 1882, he applied for patents on a 3-wire system which gave 220v transmission with 110v lamps. The Japanese took it one notch lower, they standardized on 100VAC. In Europe it happened so that 220V was considered to be suitable to be distributed directly to the consuming devices. UK happened to choose a little bit higher voltage 240V. European standardization has lead now to situation that the whole Europe has migrated to 230V standard (230V +- so much that both 220V and 240V stay within the limits)."(Actually Europe was also orginal 110)From a PDF from Pacfic Power (Utah)."PacifiCorpÆs voltage ranges are based upon Voltage Ratings for Electrical Power Systems and
Equipment, American National Standard ANSI C84.1û1989. ANSI C84.1û1989 was prepared
by the National Electrical Manufacturers Association (NEMA) with participation by the Edison
Electric Institute (EEI) and others.
Some of the stated purposes of ANSI C84.1û1989 are:
1. To promote standardization of nominal system voltages and ranges of voltage variations
for operating systems
2. To promote standardization of equipment voltage ratings and tolerances
3. To promote coordination of relationships between system and equipment voltage ratings
and tolerances
4. To provide a guide for future development and design of equipment in order to achieve the
best possible conformance with the needs of the users
In ANSI C84.1, it was noted that some utilization equipment had nameplate voltages that were
not consistent with reliable operation. The recommendation was made that the voltage ranges for
which equipment is designed should be changed as needed in order to be in accordance with the
ranges shown in Table 2 and that the voltage ratings in each class of utilization equipment should
be either the same as the nominal system voltages or related to the nominal system voltages by
the approximate ratio of 115 to 120."That makes it sound like 89 was the first offical standard for 120.http://en.wikipedia.org/wiki/Mains_electricity" Thomas Edison developed direct current (DC) systems at 110 V and this was claimed to be safer. For more information about the early battles between proponents of AC and DC supply systems see War of Currents.""Originally much of Europe was 110 V too, just like Japan and the US today. It was deemed necessary to increase voltage to draw more power with reduced loss and voltage drop from the same copper wire diameter [citation needed].The choice of supply voltage is governed more by tradition than by optimization of the distribution system. In theory a 240 V distribution system will use less conductor material to deliver a given quantity of power. Incandescent lamps for 120 V systems are more efficient and rugged than 240 V lamps, while large heating appliances can use smaller conductors at 240 V for the same output rating. Practically speaking, few household appliances use anything like the full capacity of the outlet to which they are connected. Minimum wire sizes for hand-held or portable equipment is usually restricted by the mechanical strength of the conductors. One may observe that both 240 V-system countries and 120-volt system countries have extensive penetration of electrical appliances in homes. National electrical codes prescribe wiring methods intended to minimize the risk of electric shock or fire."I have an ITT "Reference Data for Radio Engineers". 1956 with a table dated 1954 giving the principle low-voltage power in foreign countries. The US is not listed.For Canada it list 110 (predominate), 115, 120, 220, 230 @ 60hz (predominately) and 25 hz.{I know that as of 1963 that one mining company was still using 25 hz}.And for Mexico they list 110 (predominately), 115, 120, 125, 220 @ 60 & 50 hz.They also have electric motor wiring and fusing table from the 47 NEC.It list single phas motors for 115 and 230 volts, but also 3 phase motors for 220 and 440 volts.Also I can remember equipment from the 50's, 60's labeled with 117. I don't remember if that was the only number or if it might have been the upper limit on a range. For example for nominal 110 103 to 117 would be an acceptable operating range.
Okay, I think these are as thorough of replies I've read here!
Does this mean I have to break my vow of only participating in two web forums and hang out at JLC too with more smart guys?
Remind me to mind my 'lectercal Ps and Qs when you're watching next time.
Forrest
One "correction".In CA the spec was adjust to allow a slightly lower voltage.I found tid bit a couple of years ago, but could not find it again. It was done during the power "cris" in CA so that adjusted the lower spec a little.Also Europe (including England) had a number of different voltsage between 220 and 240.For the Euro market they made the spec 230 and the tolerance large enough to cover most of the current different supplies. And new equipment/supplies move to that new standard.
Yea, the CA PUC decided to intentionally "brownout" the standards in an attempt to save energy. I guess that means that in CA, good engineering practices require feeder+branch losses to be held to less than 5%; after all, they don't manufacture special "California spec" motors.
Good stuff. I love learning on these boards.
Interesting -
Do a Google search for "220 volt service" and "240 volt service" and you get a few more hits for 220 (2.5 M v 2.25M +/-)
Looks to me that either is an acceptable term to denote voltage in residences
That's kind of an interesting thing you've done there!
I'd guess it could be called "web polling" - simply counting search hits to establish relative veracity of similar items or issues.
Statistically, there may be some sense in it.
Hmmmmmmmm
Forrest
HArdly definitive, of course, but shows the term "220 volt" is widely used, and not just "firin"
That's kind of an interesting thing you've done there!
I'd guess it could be called "web polling" - simply counting search hits to establish relative veracity of similar items or issues.
Statistically, there may be some sense in it.
Hmmmmmmmm
Forrest
Oh brother. This is engineering, not polictics, or English Lit. There are right and wrong answers here.
You don't answer engineering questions with popularity contests (it would have been alot easier to get through engineering school if it was). Just because the electrical service in Europe and much of the world is 220V (and it's the colloquial term commonly used by layman in the U.S. because "220" rolls off the tongue better than "240"), doesn't mean that it's the right answer for the nominal voltage in the U.S.
Go get a copy of ANSI-C84.1 and look it up yourself, if you don't believe me.
Wait - I'm not saying its the preferred method HERE - I just think it's a novel approach to information gathering.
And I are an en-ga-neer, gol darn it!
Forrest
Barry, your answer is somewhat misleading. The ANSI standard refers to power distribution over utility lines. It does not have anything to do with nameplate markings. A manufacturer is free to mark his equipment as he likes. I have seen the following markings on nameplates (to name a few):
"240"
"230"
"220/240"
"208 /220 /240" And these were all markings that did not require any change in the wiring of the unit. Tests done, whether to NEMA or UL standards, involving over- and under-voltage operation of equipment are based upon the nameplate marking, and not any utility standard. Likewise, there are any number of things that can ensure that the appliance sees a different voltage than what some standard may call for. The "240" is a 'nominal' voltage, and has little bearing on what the device actually sees.
Barry, your answer is somewhat misleading.
It was not intented to be.
The ANSI standard refers to power distribution over utility lines.
Actually, no. It defines the standard for power delivery to a customer, not for power distribution over utility-owned lines (there are other standards for that). It defines recommended values for two different points, the "service voltage", at the point of connection between the utility and the customer, and the "utilization voltage" at the point that the wiring terminates at the equipment, which takes into account voltage drop of premises wiring.
It does not have anything to do with nameplate markings.
I guess that's the misleading part. You're right, nameplate voltages aren't defined in C84.1, I was just attempting to explain why the nominal ANSI standard for single/phase voltage is 120V/240V, but the NEMA (ANSI) standard for the single phase equipment is a bit lower (115/230). 'thought it might come up, since the two are meant to be connected, even though the follow different standards. I probably should have left the last paragraph out.
A manufacturer is free to mark his equipment as he likes.
Of course, ANSI standards are voluntary recommendations (at least until such time as some regulatory body mandates them). But if a manufacturer is claiming comliance to a NEMA standards (e.g., a motor manufacturer), then the equipment needs meet certain requirements; e.g. satisfactory operation at +/-10% of nameplate nominal.
The "240" is a 'nominal' voltage, and has little bearing on what the device actually sees.
Well I guess I disagree here. As an equipment designer, I would have to know what voltage range over which the equipment is expected to opeate satisfactorily. And that expected voltage is determined by agreed-on standards for the nominal voltage, and tolerances. If a customer complains about unsatisfactory operation, and it turns out the equipment is receiving only 190 volts, then something is wrong, and not with the equipment: either he had a bad electrician do the premises wiring, or he needs to complain to the POCO or the PUC.
Define the question and you define the answer.
Plenty of folks will know exactly what you mean (at least in the areas I've lived in) if you say "220 volt service." Say "240 volt service" and you'll get some quizical looks from some folks.
A couple of my eletrician friends tell me 240 is associated more with 3 phase (1/2 of 480) and 220 (2x110) more with residential service, and that it has to do with the taps on the transformer.
Well, they don't know much about 3-phase.
If Tyranny and Oppression come to this land, it will be in the guise of fighting a foreign enemy. --James Madison
"Well, they don't know much about 3-phase."Or single phase either.Bob, you do have a voltmeter don't you.Start measuring the voltage at receptacles for the next week or two and report what you read.
"Do a Google search for "220 volt service" and "240 volt service" and you get a few more hits for 220 (2.5 M v 2.25M +/-)"
I tried it, and got 3.5 million hits for 220 volt service, and 3.13 million hits for 240 volt service. 230 volt service got 2.3 million hits, by the way.
However, when I put the quotation marks around the phrase when I typed it in the google window (to search on the exact phrase, not just any combination of the three words), I got
"220 volt service" 555 hits
"230 volt service" 99 hits
"240 volt service" 11,400 hits
So there. :-)
Actually, based on the specs in the link you posted, it says 230V 1020W - meaning that it will draw ~4.3A
I didn't see anything RE: 20A in the specs you linked to, but I assume they meant that it should be on its own 20A circuit.
12-2 w/ a 20A double pole should be fine.
Wow - thanks for the quick replies - I have a roll of 12/2, bought when prices were more reasonable...so thats what I'll use...thanks for doing the math - I didn't remember the equation, but now it makes sense the box was calling for a 20 amp circuit, not 20 amps on the unit.
-Brian
Caution!!!!! 120v,240v. There should be some better advice on this.
If you know it's ok ,if you don't know- read on 240v circuit, or get expert help.
Don't want 20 amps hitting me on that white wire.
It can be done but needs to be marked properly.
Thanks for the caution, been doing this for quite a while, but never "marked" a 220 circuit (or seen one marked) - what do you mean?
We've always used 12/2 for well pumps etc, but 10/3 for 30 amp dryer circuits. Are you saying I need 3 wire for the window unit? The inspector will be here tuesday, and he'll set me straight, but I'd like to be code compliant before then...
Treat every person you meet like you will know them the rest of your life - you just might!
Edited 7/14/2006 10:35 am ET by Brian
Put colored tape on the white wires on both ends, to indicate that the white is not neutral.
If Tyranny and Oppression come to this land, it will be in the guise of fighting a foreign enemy. --James Madison
It's not 220 unless you? have 110 twice. New electric.
But as far as the 240 circuit- Hot is black =120v Hot is red=120v total 240v
Now if your cheating on wire and have black and white? what do we do ? Mark the white as hot=red or black. Wrap point in box with identifying red around wire. Wrap point in breaker box with red tape to identify same.
And I'm sure we will be getting some purist flames on this.
Even red or black paint or indelible permanent marker (what I use) on the white wire is OK.
Some of the math here is lacking though, nobody even considered power factor, probably 0.82 for the GE compressor motor, even less for the fan motor. Cool only unit so no heaters; say 0.80 PF overall.
1020/230(rating) = 4.43A. 4.43/0.8 = 5.54 amps. Obviously 20A circuit still OK.
Marking the wires sounds like a good idea and all, and I'll do it, but...
Can't you tell the wire's hot by the double pole breaker at the box, and by the funny plug at the receptacle end? (or with a dummy stick)
I have always called 220, 230, 240 etc. "220" by habit. Or as Mr. Mom said, "220, 221, whatever it takes"
ANYWAY - the deed is done, the house is cooling, and I'm grateful for all the info.
Treat every person you meet like you will know them the rest of your life - you just might!
It's all about safety. 20 years from now when somebody taps in to the line to run a outlet and then not knowing the secret password
wammo shocko well you get the Idea.
The thing about the 120 110 220 240 is in the olden days it was 110 but now in these newin days it's 120v. Doesn't hurt to call it what it is. Cause when I hear the other it makes me think you don't know? But my buddy is an electrician and he says the same 220. So what ever. How bout saying this- don't get hit with that 2 something power cause it'll kill ya.
This is the list of services available from my local utility (a while back the transformer on the poel went bad & we had 135/270 so they replaced the transformer & now it reads 115/230)
Single Phase, 200A, 120/240V Metering.............................................................. 2Single Phase, 200A, 120/208V Metering.............................................................. 3Single Phase, 320A, 120/240V Metering.............................................................. 4Single Phase, 400A, 120/240V Metering.............................................................. 5Three Phase, 200A, 120/240V, 4-Wire Delta Metering......................................... 6AThree Phase, 400A, 120/240V, 4-Wire Delta Metering......................................... 6BThree Phase, 200A, 277/480V, 4-Wire, OVERHEAD............................................ 7AThree Phase, 200A, 277/480V, 4-Wire, UNDERGROUND .................................. 7BThree Phase, 400A, 277/480V, 4-Wire, OVERHEAD............................................ 7CThree Phase, 400A, 277/480V, 4-Wire, UNDERGROUND................................... 7DThree Phase, 200A, 120/208V, 4-Wire.................................................................. 8AThree Phase, 400A, 120/208V, 4-Wire.................................................................. 8BThree Phase, 200A, 120/208V, 4-Wire, OVERHEAD (City Network).................... 9AThree Phase, 200A, 120/208V, 4-Wire, UNDERGROUND (City Network ............ 9BThree Phase, 400A, 120/208V, 4-Wire, OVERHEAD (City Network).................... 9CThree Phase, 400A, 120/208V, 4-Wire, UNDERGROUND (City Network)........... 9D
How do you get 3-phase 120/240 4-wire?
If Tyranny and Oppression come to this land, it will be in the guise of fighting a foreign enemy. --James Madison
It is a delta configuration with 3 240 transfomers with one of the transformers with a neutral center tap and one "high" leg.Typically used for a place with mostly motor loads, but a need for small amount of 120 for office & utility loads.Small manufacutring plant (machine shop) would be typical. And near me there is a new "pull through" car wash and while I don't have any idea of what service that they are using it would be ideal for that.
Edited 7/17/2006 11:12 am by BillHartmann
OK, so the delta isn't centered, and the 3rd leg runs at a higher voltage relative to neutral, though the voltage between "hots" is 240 all-around.Something you used to see a lot of for commercial buildings (back when the drops were made with individual wires so you could tell) is 5-wire service. I always figured this to be 208 3-phase plus another 120V leg to make a 240V service.
If Tyranny and Oppression come to this land, it will be in the guise of fighting a foreign enemy. --James Madison
Man, you're lucky! - I got so much grief a few months ago here, trying to run a dryer on 10-2, musta' been a gazillion flames tellin' me I had to have a separate insulated neutral.
Forrest
EVERYBODY knows you need an isolated neutral with a 3 point ground bus on a dryer. ;)
It's all in the socket. 3-pin (2 hots and ground) outlets are legal for air conditioners, but no longer (in new construction) for most dryers and ranges. 4-pin outlets must have 4 wires.
If Tyranny and Oppression come to this land, it will be in the guise of fighting a foreign enemy. --James Madison
a gazillion..??I think there were more than that....maybe trizillion.
.
.
.Wer ist jetzt der Idiot
?
I was think about you comment and this is not to be a disser but a couple of things? Did you use 10-2 or 10-2 w-G?
I'm not sure but the motor in the dryer is 120v? and if it is then whats the nutral on it? And if it's the bare G Then that's a problem. So if you put a meter on the G you'll find it energized. And if that's the case, other Gs will also be live?
Give me the short rundown on it?
Ummmm - boy I don't want to open up that can o' worms again.
I used 10-2 w/g. The interesting upshot of a LONG discussion here was that the dryer I bought from a neighbor across the street became "illegal" as I dollyed it across the street to my house. Their house was wired in 1980 with three-wire to the dryer; my house was wired in 1994 (with a gas dryer). Any later additions would have to be 4-wire, and required a new pigtail on the dryer - I've now redone this to protect my fragile self-esteem.
To sum up - legal there; illegal 110 feet away.
Forrest
Self esteem is not near as critical as self when it comes to shock.
It's not legal illegal,l it's the safe unsafe. I put that first on the list.
Find out why it's illegal. There are dead bodies that learned why. Don't relearn what they Know.
Lets be realistic here - are you proposing that the act of dragging the dryer across the street made it more "dangerous" - :-)
Sounds like a Steven King novel!
THE DRYER
Forrest
Edited 7/14/2006 6:22 pm by McDesign
No but here's what sometimes happens. The issue gets clouded.
In this case this is why it is so dangerous. The other house had a 10-3 W-no G you put in a 10-2 with ground. The first had a neutral to the box but no G. You used no neutral but you used the G as a G or Neutral. That energizes the G, Very dangerous. And if you didn't I don't think the motor would run.
I know, I know, I know - just trying to bring some levity into these serious discussions - hey, it's Friday, even
Forrest
I'm not jumpin on, plus I saw you other success so congratulations.
I had a buddy that almost bit his tougue off by a 240v zap. I won't go into the long of it but the original home owners had upgraded receptacles all over the house. They didn't know that it mattered which side the wires went on. What really scared me was the house, some of which was gutted had the bathroom stripped of lath and plaster but all else intact. So If someone had grabbed that 1.5" Galv vent getting out of the tub they would have been a newspaper article. It really bothered me.
....see what you did ?you're prolly sittin' there LYAO ...............
.
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.Wer ist jetzt der Idiot
?
"In this case this is why it is so dangerous. The other house had a 10-3 W-no G you put in a 10-2 with ground. The first had a neutral to the box but no G. You used no neutral but you used the G as a G or Neutral. That energizes the G, Very dangerous. And if you didn't I don't think the motor would run."Not exactly.It is as danagerous or as safe as 3 wire dryer can be.Technically the dryer can be wired with 2 insulated wires and a "bare wire". That is if SE cable is used (don't even know if it is available for in #10, but it was commonly used for similar 3 wire range connections).But if other cables, or conduit was used then the 3rd wire had to be a white "neutral".In either case it was serving as a neutral, but the case of the appliance was also bonded to it.And the neutral wire was connected to bonded neutral/ground bus at the main panel. Even under the old rules I don't think that 3 wire could be used if it was wired through a sub-panel (IE, where the ground and neutral where not bonded).
I remember getting jolted from touching an electric stove that had a toaster plugged into the "convenience" outlet. 3-pin plug on the stove and the center pin wasn't making good contact.
Got a piece of wire and found I could make some good sized sparks by tying one end to the plumbing and touching the stove trim with the other.
This was about 40 years ago -- I've been a fan of 4-pin plugs ever since then.
If Tyranny and Oppression come to this land, it will be in the guise of fighting a foreign enemy. --James Madison
I'm sorry, but it seems this question makes things unnecessairily hard.
The nameplate of air conditioners typicall have some very specific information on them.
They will state "Max" and "Min" overcurrent protection necessary. These would be your circuit breaker sizes. If they simply say "Maximun size fuse..." then there must be a fuse, and not just a circuit breaker, somewhere in the circuit.
Theye will also state "minimum circuit ampacity." This figure...in amps... is used with tables in the NEC to select the smallest allowed wire size.
Watts, BTU's, Tons, horsepower... all these things are irrelevant. The nameplate already has the info you need.
"he nameplate of air conditioners typicall have some very specific information on them.They will state "Max" and "Min" overcurrent protection necessary. These would be your circuit breaker sizes. If they simply say "Maximun size fuse..." then there must be a fuse, and not just a circuit breaker, somewhere in the circuit."This is a WINDOW AC.It has been awhile since I looked at one, but I don't believe that it has that on the lable.
The box said 20 amp, and so I thought... 16 amps is the max load for a 20 amp circuit w/ 12 wire and losses...
and I was wondering how a window AC could draw so much current.
It turns out it doesn't, the box was giving the circuit size only. It draws around 12 amps, the info in the manual contradicted the box.
Frankly, I'm honored to have 35 posts (so far) on a discussion I started, and I learn something everytime...
and by the way - the house is nice and cool now.
Treat every person you meet like you will know them the rest of your life - you just might!