electric outlet for window AC question

From: snipped-for-privacy@aol.com On 8 Jun 2005 04:21:48 GMT, snipped-for-privacy@ipal.net wrote: It could just be that I can't find the part of the code that says a 15 amp circuit cannot have a 20 amp receptacle

Look at 210.21(B)(3) again. The top line says 15a circuits shall have receptacles "not over 15a"

~>Exactly: I do know why Phil argues anything to the contrary., I even explained what could physically happen to a 15A receptacle on a @20A circuit. =AEoy

Phil look at TABLE 210.21(B)(3) NEC every year since the FDR administration.

Phill has a point. 210.21 (B) (3) would not appear to apply to branch circuits that only have one outlet. I strongly suspect that was not what the code making panel intended but the way 210.21 (B)(1) reads now you could put a twenty ampere receptacle as the only outlet on a fifteen ampere circuit.

That's the point: you can use a 20A outlet on a 15A circuit, but He argues a 15A outlet can handle the 20A circuit which would toast the recept when & if the load overshoots the 15A on a steady basis.

You see that allot in countertop/shop type businesses where they callously plugging all sorts of things and run extension cords for multiple outlets from them with loads greater than 15A. [well maybe not as common, but I've eliminated a few of these type of violations] Roy /~>

From: snipped-for-privacy@mindspring.com (HorneTD) snipped-for-privacy@aol.com wrote: On 9 Jun 2005 01:17:55 GMT, snipped-for-privacy@ipal.net wrote: On Wed, 08 Jun 2005 11:42:48 -0400 snipped-for-privacy@aol.com wrote: | On 8 Jun 2005 04:21:48 GMT, snipped-for-privacy@ipal.net wrote: | It could just be that I can't find the part of the code that says a 15 amp circuit cannot have a 20 amp receptacle | Look at 210.21(B)(3) again. The top line says 15a circuits shall have | receptacles "not over 15a" What code are you looking at? The top line of what I have says "Where connected to a branch circuit supplying two or more receptacles or outlets, receptacle ratings shall conform ..." Phil look at TABLE 210.21(B)(3) NEC every year since the FDR administration. Phill has a point. 210.21 (B) (3) would not appear to apply to branch circuits that only have one outlet. I strongly suspect that was not what the code making panel intended but the way 210.21 (B)(1) reads now you could put a twenty ampere receptacle as the only outlet on a fifteen ampere circuit.

On Wed, 08 Jun 2005 22:44:02 -0400 snipped-for-privacy@aol.com wrote: | On 9 Jun 2005 01:17:55 GMT, snipped-for-privacy@ipal.net wrote: | |>On Wed, 08 Jun 2005 11:42:48 -0400 snipped-for-privacy@aol.com wrote: |>

|>| On 8 Jun 2005 04:21:48 GMT, snipped-for-privacy@ipal.net wrote: |>| |>|>It could just be that I can't find the part of the code that says |>|>a 15 amp circuit cannot have a 20 amp receptacle |>| |>| Look at 210.21(B)(3) again. The top line says 15a circuits shall have |>| receptacles "not over 15a" |>

|>What code are you looking at? The top line of what I have says "Where |>connected to a branch circuit supplying two or more receptacles or outlets, |>receptacle ratings shall conform ..." | | | Phil look at TABLE 210.21(B)(3) NEC every year since the FDR | administration.

Read the text of 210.21(B)(3) to see what TABLE 210.21(B)(3) applies to. My copy says it applies to "branch circuit supplying two or more receptacles or outlets". Is yours different?

| That's the point: you can use a 20A outlet on a 15A circuit, but He | argues a 15A outlet can handle the 20A circuit which would toast the | recept when & if the load overshoots the 15A on a steady basis.

Do you have a modern 15A UL listed receptacle of USA manufacture that will become toast with 20A of total load?

| You see that allot in countertop/shop type businesses where they | callously plugging all sorts of things and run extension cords for | multiple outlets from them with loads greater than 15A. [well maybe not | as common, but I've eliminated a few of these type of violations] Roy | /~>

More likely cheap plugs making poor contact are arcing inside producing far more heat than if 20A were condtinuously running through the device.

I did disasemble (destructive of the plastic parts) a high quality brand duplex receptacle, one each of 15A and 20A, ever years ago. The metal parts that carry electric current were exactly identical between them, right down to the extra contacts for the "T" side slot on the neutral that would never be used in the 15A version unless you were to drill the plastic out and make such a slot yourself (e.g. "field conversion of a

Not every receptacle will be like that. I only did that because I could see those "T" contacts in the 15A version. At the time I didn't even know that it was legal to use the 15A version on a 20A (multi outlet) circuit.

The cheaper receptacles may be of lesser quality, but to get the UL listing it is my understanding they _must_ meet the requirement of being able to handle a _total_ of 20A when adding up all the current loads from BOTH of the outlets AND downstream loads on the 2nd set of terminals, all going through the line terminals.

In theory, the contacts of ONE outlet might not handle more than 15A, but it is expect that a device running 16 to 20 amps of current will not have a NEMA 5-20P plug on it. Then that is not that much more heat and is not going to make that much difference. If 20A were to toast it, 15A would be awfully damned HOT ... and that's not safe anyway.

The odds are that it will be about the same as what you paid for the air conditioner.

I note that Walmart sells 240 units when you get to the 10,000 BTU/hour size. If you have room for another two pole breaker in you box, it may be about the same charge from the electrician and you may be happier with a larger a/c.

If you run a new circuit, the electrician likely would want to connect it to a new breaker.

Likely, that's a 15 amp "lighting" circuit. Find an unswitched wall outlet. You CAN use a heavy duty extension cord. See if it still "trips." You can save some money.

As I said, if you are starting from "scratch" then consider going to a 240 unit.

For all it's worth, in Massachusetts its about $5/amp. So a 200 amp service panel is one grand.

Al

Roy Q.T. wrote: > That's the point: you can use a 20A outlet on a 15A circuit, but He > argues a 15A outlet can handle the 20A circuit which would toast the > recept when & if the load overshoots the 15A on a steady basis. >

Roy Step one this is Usenet so please stop top posting. The protocol for Usenet is to add your reply at the bottom of all quoted text and to keep the quotes in posted order.

UL test receptacle outlets to feed through much higher loads then the pattern of the receptacle is meant to supply. A fifteen ampere receptacle will certainly handle twenty amperes without any additional risk of failure. The real danger is that the installation of a twenty ampere receptacle on a fifteen ampere circuit can lead to chronic overloading and nuisance tripping of the over current protective device. That in turn will cause a user to be tempted to replace the OCPD with one that is two high to protect the circuit wiring.

Back to the orig> ~>Exactly: I do know why Phil argues anything to the contrary., I even

Remember to size the a/c, to small and the room wont cool off. to large of an a/c and the a/c will not remove the humidity from the air, causing you to keep the temperature lower to be comfortable. I think that the a/c will cycle faster and compressors do not like starting up.

Stephen B.

...

FWIW, I have an el-cheapo 15A recepticle that has on its back "FOR 15A BRANCH CIRCUIT ONLY" (and repeated in French) as well as "15A 125V" on the front near the screw hole. I also noticed the holes for back wiring were awful small, and a little experimenting showed they were the exact right size for #14 wiring. Which means that you couldn't use #12 there if you wanted to! Of course you could (should) still use the screw terminals but someone back wiring it must use #14! Take a look at the cheap recepticles at Home Depot which I think is where it came from.

Well, you can compensate for that by running the A/C on "LOW." Most machines will really pump out the moisture then.

I know the conventional "wisdom" is better slightly too small than too big. But when you have a HOT day and you A/C is too small, you might as well just open the windows.

Argue all you want, FireMouth Tom: I'll reply as I can, if you don't like it, fine, but don't Misdirect the public or tell me what to do nor how to do it.....I never thought i'd say this but go jump on a Candy Apple Red Truck and leave this alone.

FACT IS: 15A receptacles should be used on 15A circuits and if you think nothin of it put it on a 20A circuit., The Danger is not only in overloading a 15A circuit with a 20A load but having a perfect 20A circuit with a 15A receptacle can cause a fire Maybe not today or tomorrow but in the long run, when others forget it's not rated and plug in an overload. be it as may be, they are not the same physically., AND as per the NEC - 20A receptacles are allowed on a 15 Amp circuits whether you like it or not., it is safe at the user or end level, Now F*ck Off !

Additional residence time of the air over the cooling fins will take out a bit more moisture, but that is at the expense of poor air circulation and higher than needed operating costs.

Conventional wisdom is to have the RIGHT size and you get maximum efficiency and comfort.

Well, the "right" size determination uses ASSUMPTIONS about the outside temperature and the heat load. Combine an extra hot and humid day with having a few folks over or just arriving back home after a day or two of your home being "heat soaked" and your conventional wisdom becomes nonsense.

The problem with running a room conditioner at low is that the outside coil doesn't get as much circulation but it sure does suck the water out of the air.

To each his own, but if you have the electrric power and the spare cash when you buy a window unit, go for a larger size. "Efficiency" just ain't all that important if all you are cooling is ONE room. >

NEC - 20A receptacles are allowed on a 15 Amp circuits

Just use an extension cord

Easy, Efficient and Affordable

By a cord rated at 20 amps, snip the plug end off, wire it direct into a 20 amp breaker, plug the A/C in the other end and all done.

Simple!

Cheers

No, conventional wisdom still works. Why risk having an unsatisfactory situation 95% of the time when the exception is only 5% of the time?

And the inside of the room is not getting proper air circulation either.

One room may not cost much, but comfort is more important. Maybe you just have not experienced it properly. That does not mean it does not exist.

Because its when it's hot as hell outside that you want an A/C that can keep you cool.

It's "nice" the have an A/C that "pumps" the exact amount of heat AND you can pay to get a variable capacity central unit. If you have a window unit, you can reduce capacity by lowering the fan speed, by putting a heater in the room (this used to be standard in "computer rooms" where it was essential to keep the RH within a certain range), or by permitting a little circulation to the remainder of the house. But during those HOT days, that "extra" capacity is a blessing.

Big deal. Turn on the ceiling fan. It will mix the air and even had a few watts of heat load. And it's fun to watch. Problem solved.

You are being silly. If you have a fixed capacity window unit you can size it to be "too big" all the time (and play games with fan speed to adjust capacity) or get a unit that's too small some of the time and be downright miserable. I will gladly sacrifice a few "perfect" days to avoid a single "miserable" day