Cwhyu2
Consultant
You need a muti-meter to test that outlet.
What size wire for a 230 volt 20 amp breaker?
- Thread starter Erico
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Jadnashua
Retired Defense Industry Engineer xxx
My limited experience with EMT (I'm assuming that's what you have) is that over the years, there's enough corrosion on the connections that it is no longer a decent ground path. It would be easier to test if it were a 120vac receptacle. But, measure from each leg to the ground lug. THen, go to the panel and measure them at the CB to the bus ground. If there's a difference, that means that the grounding path is not great. It would be best if you measured that while the a/c unit was running.
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From the data plate;
A). That's an old 12,000 BTU air conditioner commonly referred to as a ONE TON unit.
B) it draws 9 amps, very inefficient by today's standards. A typical 12,000 BTU/240 volt AC today only draws 5 1/2 Amps.
From the receptacle in your picture that is a 15 amp/240 volt receptacle, NEMA 6-15R. That's the correct receptacle for that AC.
That circuit should be on a 15 Amp/240v double pole breaker.
You can verify its properly grounded by using a voltmeter to check,
From hot to hot you should measure 220-240 volts
From round ground lug to both hots you should measure 110-120 vac.
The white wire is likely a hot wire. If so mark it as such with tape or marker.
BUT CHANGE THE BREAKER TO A 15a double pole breaker!!!!!
A). That's an old 12,000 BTU air conditioner commonly referred to as a ONE TON unit.
B) it draws 9 amps, very inefficient by today's standards. A typical 12,000 BTU/240 volt AC today only draws 5 1/2 Amps.
From the receptacle in your picture that is a 15 amp/240 volt receptacle, NEMA 6-15R. That's the correct receptacle for that AC.
That circuit should be on a 15 Amp/240v double pole breaker.
You can verify its properly grounded by using a voltmeter to check,
From hot to hot you should measure 220-240 volts
From round ground lug to both hots you should measure 110-120 vac.
The white wire is likely a hot wire. If so mark it as such with tape or marker.
BUT CHANGE THE BREAKER TO A 15a double pole breaker!!!!!
Erico
Member
Will definitely change to a 15a double pole breaker.
Question: if I upgrade to a new unit, will I have a problem with not having a nuetral wire as someone mentioned up thread ? Do the new units require a nuetral to run (digital?) controls?
You do not need a neutral.
Is your sleeve 25.5 by 15.25 inches?
http://www.catalog.commercial.carri.../0,2734,CLI1_DIV41_ETI4925_NBD_PRD598,00.html
https://www.ajmadison.com/guides/air_conditioner/wall/
Is your sleeve 25.5 by 15.25 inches?
http://www.catalog.commercial.carri.../0,2734,CLI1_DIV41_ETI4925_NBD_PRD598,00.html
https://www.ajmadison.com/guides/air_conditioner/wall/
Jadnashua
Retired Defense Industry Engineer xxx
A neutral is only needed if the appliance uses 120vac for some electronics verses 240vac. Some do, many don't. An electric stove does since it tends to use 120vac light bulbs, and maybe a convenience outlet. Most other things do not.
The line-neutral or ground at the receptacle may not read the same there as back at the panel. IF the ground or neutral is not wired, you'll get nothing on the line-neutral or ground with a multimeter. If you do get a voltage, then the quality of that connection should be very close to the same at the panel feeding it and at the receptacle, which is what I was trying to explain earlier. If those two values are more than a few volts different, there's an issue. The longer the cable, the bigger the difference when it is using power. With the appliance off, there may not be much of any difference. But in no case, if the connections are good quality, should it be very much different. After many years, rust and corrosion and thermal cycling, the screws can work their way loose if not installed at the proper torque. Few people use a torque screwdriver, and rust overtakes that in the long run.
The line-neutral or ground at the receptacle may not read the same there as back at the panel. IF the ground or neutral is not wired, you'll get nothing on the line-neutral or ground with a multimeter. If you do get a voltage, then the quality of that connection should be very close to the same at the panel feeding it and at the receptacle, which is what I was trying to explain earlier. If those two values are more than a few volts different, there's an issue. The longer the cable, the bigger the difference when it is using power. With the appliance off, there may not be much of any difference. But in no case, if the connections are good quality, should it be very much different. After many years, rust and corrosion and thermal cycling, the screws can work their way loose if not installed at the proper torque. Few people use a torque screwdriver, and rust overtakes that in the long run.
DonL
Jack of all trades Master of one
Erico
Member
I think so.
Erico
Member
Yes. The one in the other room is 8k. Same set up.
Jadnashua
Retired Defense Industry Engineer xxx
The cb sizing dictates the minimum sized wiring required. A 20A circuit, doesn't matter if it is 120 or 240vac, requires at least 12g wire...amps are amps, and 20 of them require 12g, regardless of what is plugged in...
Anyone putting a 20A breaker on 14g wire either doesn't know anything, or just doesn't care, nor would it pass any inspection by a competent inspector. The idea is: when you have a plug designed to allow a certain maximum power, the circuit should match it. The cbu is protecting the wire, not the device, and a 20A breaker on 14g wire could allow that wire to overheat.
Anyone putting a 20A breaker on 14g wire either doesn't know anything, or just doesn't care, nor would it pass any inspection by a competent inspector. The idea is: when you have a plug designed to allow a certain maximum power, the circuit should match it. The cbu is protecting the wire, not the device, and a 20A breaker on 14g wire could allow that wire to overheat.
Erico
Member
Yes. Definitely going to change the breaker.
I was intrigued by Speedy Petey's comment up thread that one might find a 20a breaker on #14 if it was a hard wired appliance. Maybe someone used that same rule or logic that allows sizing the wire to the known draw and misapplied it to the current scenario considering this IS a dedicated receptical.
Either way. I prefer to play it safe. I suppose a worse case scenario could be something like a motor seizing up and over heating the #14 wire before the 20a breaker tripped.
Speedy Petey
Licensed Electrical Contractor
Have you ever seen a wall or window A/C with a 4-wire plug?? I surly haven't. Does one even exist?
Speedy Petey
Licensed Electrical Contractor
Or someone simply didn't care or know about codes. Well quite often get folks asking if they can simply change a 15 to a 20 because it is tripping. Not even considering the safety implications, or that the breaker might actually be sized according to the wire.
Erico
Member
At least they asked an electrician. My neighbor's dad was going to install a 20a breaker for that same reason.
He's also a guy who wires light switches to the neutral. We had words over that one. He told me that's the way he's always done it and it works just fine. He even called his electrician buddy on speaker phone to prove me wrong. The diplomatic pause and explanation by the electrician was hilarious. "Umm ahh wellllll no"
Jadnashua
Retired Defense Industry Engineer xxx
FWIW, neither my central air or air handler have a neutral at them, and at least the air handler has an electronic circuit board in it (variable speed fan controller). Often, unless there's some reason to need 120vac at a 240vac appliance, they do not provide it. A stove is a common one since trying to find 240vac light bulbs for the oven would be a major problem for most. Some electric driers do so that they can use the same controls for both their electric and gas ones (the timers).
All it takes to turn an electric circuit off is to disrupt that path, and that can easily be done by breaking the power to it, or the return (neutral) from it. Breaking the power to it is much safer, and is the way the codes are written to correspond. But, functionally, if you don't care about safety, either one works.
What may be complicating things now, is that I've heard, they want neutral at the switch. As I understand it, that would make swapping to a smart switch, some dimmers, and other type controlling devices possible at some later point. To save wire and routing issues, often, the only thing there is a switch leg. Codes get updated to account for past issues and new features...IOW, it's a moving target from things learned and new possibilities. Not all electricians, like many tradesmen, always keep up properly. Then, throw in the states and locales that don't always update to the newest codes right away. It can be tough deciding what's proper at a specific location.
All it takes to turn an electric circuit off is to disrupt that path, and that can easily be done by breaking the power to it, or the return (neutral) from it. Breaking the power to it is much safer, and is the way the codes are written to correspond. But, functionally, if you don't care about safety, either one works.
What may be complicating things now, is that I've heard, they want neutral at the switch. As I understand it, that would make swapping to a smart switch, some dimmers, and other type controlling devices possible at some later point. To save wire and routing issues, often, the only thing there is a switch leg. Codes get updated to account for past issues and new features...IOW, it's a moving target from things learned and new possibilities. Not all electricians, like many tradesmen, always keep up properly. Then, throw in the states and locales that don't always update to the newest codes right away. It can be tough deciding what's proper at a specific location.
Ballvalve
General Engineering Contractor
The tripping was my first thought as to why the 20a breaker is there. Therefore, the FIRST thing to do is put a ammeter on the hot wires when it is running and find out how many amps it is pulling. If it is much above the name plate, its time to retire the entire unit. I am rather surprised no one has suggested that test in all these replies. A poor "test" is putting in the the 15 amp breaker. Perhaps its pulling 14 amps... and that's a unit you don't really want running.
Speedy Petey
Licensed Electrical Contractor
It is not a test. It is correcting a pre-existing problem.
DonL
Jack of all trades Master of one
No I have not seen 4 conductors on a window unit. Only on the bigger units, Most of them are hardwired to a disconnect. Some do have pigtails. Many of them have switching power supplies for the controls, they can run on any AC voltage and 50 or 60 Hz.
If you have a window unit that runs on 240, You most likely need something better than a window unit.
Speedy Petey
Licensed Electrical Contractor
Even bigger units are pretty much all 240V (or 208V, or 480V) and do not require a neutral.
Ballvalve
General Engineering Contractor
Okay, where is the amp read while running from the original poster? Yes. change to a 15 amp breaker. But also find out what this antique is drawing in amps. That makes the decision to replace the unit easy.
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