Portable AC unit in older home


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Old 08-19-14, 12:48 PM
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Portable AC unit in older home

I apologize if this question has already been answered, but I couldn't find a post that dealt directly with my question.

I live outside Detroit, MI in a bungalow built in 1952. I recently purchased a portable AC unit to cool the attic living area. According to the specs, the unit draws 10.8A/1500W. The outlet it's plugged into is original equipment, and the wiring appears to be 14/2 (no ground) on a 15A circuit. (There are no other larger appliances on the circuit; the circuit is not overloaded with the AC unit running). This wiring is also original equipment, so it is over 60 years old. The outlet is a 2-prong, and the AC unit (which has an inline circuit breaker in the power cord) is a 3-prong, so I am using a new 15A adapter. After a typical summer day usage, the adapter does not seem to be overly hot to the touch. I'm wondering if this setup sounds safe electrically. Thanks in advance for any responses.


Steve
 

Last edited by delta1071; 08-19-14 at 12:51 PM. Reason: add info
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Old 08-19-14, 01:10 PM
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Better would be to replace the ungrounded receptacle with a GFCI receptacle. Then you wouldn't need the adapter.
 
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Old 08-19-14, 01:22 PM
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Thanks Ray. I plan to replace the outlet with a GFCI. I guess my main concern is that the old wiring may not be able to handle the load.
 
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Old 08-19-14, 02:14 PM
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If the old wiring is jumper-ed from outlet to outlet on its way to the third floor even though nothing else is running, there can be a problems with loose or poor connections. There are meters that can load test a receptacle. At a minimum I would want to have all connections en-route to that location inspected and tightened.

Bud
 
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Old 08-19-14, 03:25 PM
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(which has an inline circuit breaker in the power cord)
You can install a GFCI receptacle, however it will be redundant. That device on the power cord is not a circuit breaker, it is a GFCI. This has been required on newer-ish A/C units for quite a few years now. If you look at the cord device it will have a test and reset button that you find on other GFCIs.
 
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Old 08-19-14, 04:46 PM
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Just to clarify the GFCI is so he can use a grounded plug without an adapter.
 

Last edited by ray2047; 08-19-14 at 06:57 PM.
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Old 08-19-14, 08:49 PM
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You can install a GFCI receptacle, however it will be redundant. That device on the power cord is not a circuit breaker, it is a GFCI. This has been required on newer-ish A/C units for quite a few years now. If you look at the cord device it will have a test and reset button that you find on other GFCIs.

What is on an air conditioner plug is what's called a LCDI, and will not trip from a line-to-ground short.
 
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Old 08-20-14, 08:06 AM
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Sounds like replacing the outlet with a GFCI is what I need to do. Thanks for the responses.
 
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Old 08-20-14, 08:43 AM
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Yes that would be the code compliant way without running a new dedicated circuit.
 
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Old 08-20-14, 08:50 AM
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Sounds like replacing the outlet with a GFCI is what I need to do. Thanks for the responses.
60 year old house likely means tight boxes... GFCI's are bulky, might not even fit.

Have you considered running a new grounded circuit for your AC if practical? You can kill 2 birds with one stone sort to speak.

If the old wiring is jumper-ed from outlet to outlet on its way to the third floor even though nothing else is running, there can be a problems with loose or poor connections. There are meters that can load test a receptacle. At a minimum I would want to have all connections en-route to that location inspected and tightened.
In my opinion fed thru outlets are not any more or less likely to develop a loose connection than wirenuts, solder, crimp caps, friction tape or whatever else means of splicing you might find in a 60 year old house.
 
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Old 08-20-14, 08:56 AM
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What is on an air conditioner plug is what's called a LCDI, and will not trip from a line-to-ground short.
wright............................it will only trip when a "current leakage occurs"

we call that a short.
 
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Old 08-20-14, 09:04 AM
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Dirtydickey makes valid points. A dedicated circuit is always best. If you just can't and the wiring method is not metallic cable (AKA BX) or conduit you might want to replace the box with a plastic deep old work box if you don't have enough room. The second thing you can do to improve the circuit is at each box on the breaker with two cables is remove the cables and connect the wires to a pigtail and the pigtail to the receptacle.
 
 

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