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Discussion Starter · #1 ·
I am installing a small mini split for a bedroom. I live in an hurricane prone area and will possibly power this with my generator.

Because of using it with a generator, I decided to use an outdoor 20 A receptacle for running my outdoor compressor instead of a simple pull out disconnect. I called the manufacturer and they told me no problem with this...as well as running the unit off of a generator. This will also enable me to simply power it with a extension cord going from my generator and not risk back feeding the supply power when it gets restored.

OK.....I am using an outdoor bubble cover box and when I went to install my receptacle it hit me that maybe I should use a GF receptacle? Would you guys use one? I really don't want nuisance trips and wasn't sure if using a GF to feed an appliance was recommended. Also...most AC's use a simple pull out disconnect which provides no GF protection.

What do you guys think? GF or no GF?

Thanks :smile:
 

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It's required, not optional. It's an outdoor receptacle, so it must have GFCI protection.
 

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good chance your outdoor receptacle is already on a gfi. Unless your house is really old. A lot of times the outside receptacle is tripped by the bathroom gfi. Now if your running a hair dryer and the a/c that may be an issue. Worth looking into whatever else in on the receptacle circuit.
 

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Discussion Starter · #4 ·
I ran the new receptacle from the meter panel. BTW...I built the home and installed all of the electric myself so I know what receptacles are GF protected or not. But, I'm not asking about code or anything. I am aware that all receptacles outside need a GFI according to code but this is not getting inspected.

What I am asking is does a GFI cause problems with an AC Compressor? They most always have a pull out disconnect which is not GFI protected. If the disconnect is not GFI protected then why does my receptacle have to be? I don't mind throwing a GFI receptacle in the box but I've never seen a small compressor being connected with a receptacle before and I want to make sure the GFI will not cause errant trips.
Thanks
 

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If you have a 120VAC 20A receptacle it has to be GFCI protected because despite your logic the outlet could be used for other purposes and thus requires protection.



Nuisance trips are largely folklore, modern GFCIs are well designed to avoid false tripping. Many actual ground fault conditions are incorrectly categorized as nuisance trips..

If you have a 240VAC 20A circuit going to a NEMA 5-15 or 5-20 style receptacle you are violating code.
 

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Discussion Starter · #6 ·
If you have a 120VAC 20A receptacle it has to be GFCI protected because despite your logic the outlet could be used for other purposes and thus requires protection.



Nuisance trips are largely folklore, modern GFCIs are well designed to avoid false tripping. Many actual ground fault conditions are incorrectly categorized as nuisance trips..

If you have a 240VAC 20A circuit going to a NEMA 5-15 or 5-20 style receptacle you are violating code.
Again....I realize the code violation. BTW...it's a 115 receptacle but no matter. What I am asking is if anyone has heard of a GFI not being recommended on these newer inverter mini split condensers. I thought I read that somewhere? I know the newer Combo arc/ground protection devices have a bunch of problems with appliances with hermetically sealed motors and was wondering if the GFI's do?
 

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Again....I realize the code violation. BTW...it's a 115 receptacle but no matter. What I am asking is if anyone has heard of a GFI not being recommended on these newer inverter mini split condensers. I thought I read that somewhere? I know the newer Combo arc/ground protection devices have a bunch of problems with appliances with hermetically sealed motors and was wondering if the GFI's do?

You're not likely going to find much feedback about the pitfalls of connecting a mini split to a GFCI receptacle because most installs aren't done that way.
 

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Discussion Starter · #8 ·
You're not likely going to find much feedback about the pitfalls of connecting a mini split to a GFCI receptacle because most installs aren't done that way.
Thanks...I realize most don't install using a receptacle. Most use a simple pullout disconnect. I just want an easy way to connect the Genset. Anyway...I will try the GFI and see if it trips. If it does...I will simply break the code and put a normal outlet in there.
 

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A different way to connect the generator would be to wire the compressor to a DPDT switch, with one side of the switch connected to the feed from the breaker panel and the other side connected to an inlet box for the generator to connect to. No need for a GFCI that way.
 

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Discussion Starter · #10 ·
A different way to connect the generator would be to wire the compressor to a DPDT switch, with one side of the switch connected to the feed from the breaker panel and the other side connected to an inlet box for the generator to connect to. No need for a GFCI that way.
Yeas....but the generator supplies other circuits in the upstairs house as well. I have a male pigtail that plugs into an interior wall outlet that backfeeds the inside breaker panel. This allows me to energize single circuits as desired an leaving the main feed breaker closed to prevent backfeeding the power pole. If I hooked a switch, I would still need that switch to be connected to a receptacle somewhere outside underneath the house or leave a permanent extension cord wired up to the switch for when the power goes out. Seems like a lot of trouble...
I may simply install a GFI and see if it trips with the harmonics generated by the inverter. I have been using Google and it seems like my chances are not that good though. Here is a sample thread about a guy using a water cooled grinder powered by an inverter that trips a GFI..
https://forums.mikeholt.com/showthread.php?t=92263
 

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In many jurisdictions, the AC needs to be on a dedicated circuit. I believe most places don't allow it to be run through a plug like you've done. So even if you put the gfci, you could still be breaking code.

The inverter and / or compressor may leak enough current to ground to trip the gfci. It may only happen at certain frequencies. (The inverter frequency is modulated, according to the motor rpm required at that time.) The very specific nature of this, would be due to the specific reactance of the system. Anyways, this means that it may work just fine, or may trip at very unpredictable times, as you have very little control over the internal logic of the AC.

PS. I Highly suggest using an inverter generator. At least use a generator with a THD of less then 5%. It'll be marked on the box like that.

Even though we generally don't recommend anything that intentionally breaks code, you're going to do this anyways. The preferable way would be to use a transfer switch.

Cheers!
 

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Discussion Starter · #12 ·
In many jurisdictions, the AC needs to be on a dedicated circuit. I believe most places don't allow it to be run through a plug like you've done. So even if you put the gfci, you could still be breaking code.

The inverter and / or compressor may leak enough current to ground to trip the gfci. It may only happen at certain frequencies. (The inverter frequency is modulated, according to the motor rpm required at that time.) The very specific nature of this, would be due to the specific reactance of the system. Anyways, this means that it may work just fine, or may trip at very unpredictable times, as you have very little control over the internal logic of the AC.

PS. I Highly suggest using an inverter generator. At least use a generator with a THD of less then 5%. It'll be marked on the box like that.

Even though we generally don't recommend anything that intentionally breaks code, you're going to do this anyways. The preferable way would be to use a transfer switch.

Cheers!
Thanks.
See my post above. This AC is on a dedicated circuit. I just installed it. The Genset will supply power to more than one circuit but that's OK.
Please understand...I am not worried about how the Genset will affect the GFI feeding the condenser. That will never happen. The Genset is only for emergencies and it may actually be used once every 5 years. At that point the AC would simply be plugged into the Genset via and extension cord. No GFI involved. And no...I'm not buying another generator unless I have to. Too expensive for my budget.

I guess I should have not mentioned any of the particulars and kept it very simple. Basically.....all I want to know is if GFI's can work feeding mini split inverter/condensers without any issues. That it in a nutshell....
 

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Thanks.
See my post above. This AC is on a dedicated circuit. I just installed it. The Genset will supply power to more than one circuit but that's OK.
Please understand...I am not worried about how the Genset will affect the GFI feeding the condenser. That will never happen. The Genset is only for emergencies and it may actually be used once every 5 years. At that point the AC would simply be plugged into the Genset via and extension cord. No GFI involved. And no...I'm not buying another generator unless I have to. Too expensive for my budget.

I guess I should have not mentioned any of the particulars and kept it very simple. Basically.....all I want to know is if GFI's can work feeding mini split inverter/condensers without any issues. That it in a nutshell....
You've misunderstood my post. Please reread.

The better generator is to protect the electronics of the AC, not the gfci. The power supply side of the electronics really won't line the harmonic distortion of a typical generator. It'll work, but only for a fairly limited time. (How long? It's hard to say, as there's many factors involved.)

If is a plug, it's not dedicated, even though it's the only thing CURRENTLY plugged into it. Like I said, while I don't agree to it, you're still going to do it, so I answered your question, and added more info then you requested. The gfci may or may not trip, and if it trips, it may be very intermittent. ACs are not required to be gfci protected everywhere that I know of.

Cheers!
 

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The reason most units are not gfi protected is because they are 240 volts, not 120.
 
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Discussion Starter · #16 ·
Just a follow up.
I installed a GFI even though...as I wrote above...I had my reservations and sure enough....bam....trips as soon as the compressor starts up. So I quickly change out to a normal receptacle and works like a champ.
My AC friend who came out and vacuumed my lines told me that a GFI never works on these mini splits. He also said a GFI is not required (even though I disagree because of the 120V condenser) and didn't see anything wrong with me using a plug that would quickly connect to my genset. I feel fine about it because the receptacle and the condenser is 11 ft off the ground and only accessible by a ladder. It is obviously only for the AC and no one will ever, ever use it to plug other equipment into the receptacle except for the initial vacuum.
Thanks to everyone!
 

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Just a follow up.
I installed a GFI even though...as I wrote above...I had my reservations and sure enough....bam....trips as soon as the compressor starts up. So I quickly change out to a normal receptacle and works like a champ.
My AC friend who came out and vacuumed my lines told me that a GFI never works on these mini splits. He also said a GFI is not required (even though I disagree because of the 120V condenser) and didn't see anything wrong with me using a plug that would quickly connect to my genset. I feel fine about it because the receptacle and the condenser is 11 ft off the ground and only accessible by a ladder. It is obviously only for the AC and no one will ever, ever use it to plug other equipment into the receptacle except for the initial vacuum.
Thanks to everyone!
" At least you found out real quick your A/C friend was right, you have to start listening to your HVAC friends"
 

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"Yeas....but the generator supplies other circuits in the upstairs house as well. I have a male pigtail that plugs into an interior wall outlet that backfeeds the inside breaker panel."

I think he plus the AC unit directly AND runs a suicide cord.
 

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"Yeas....but the generator supplies other circuits in the upstairs house as well. I have a male pigtail that plugs into an interior wall outlet that backfeeds the inside breaker panel."



I think he plus the AC unit directly AND runs a suicide cord.
Possibly. Unless he's plugging into that outlet that he tried to install a gfci, it is just speculation, and doesn't match the thread.

Cheers!
 
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