# 25amp max OCPD on heat pump



## WronGun (Oct 18, 2013)

I recently wired a Mitsubishi heat pump. 

Min circuit ampacity 21 amps, Max OCPD 25amp

My problem is where the hell do you get a 25 amp gfci breaker for a GE panel. I have a 20amp installed and it trips instantly on startup. 










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## Dennis Alwon (May 9, 2009)

Are you using gfci because of the 2020 nec? I would install a 30 amp gfci at the unit and a standard 25 amp at the panel


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## WronGun (Oct 18, 2013)

Dennis Alwon said:


> Are you using gfci because of the 2020 nec? I would install a 30 amp gfci at the unit and a standard 25 amp at the panel


Yes 2020 Nec. 

I’ve never had to do a heat pump like this. What a pain. 


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## Dennis Alwon (May 9, 2009)

Not that big a deal. It is a bit more costly using a breaker disconnect but it will work and it is compliant


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## Dennis Alwon (May 9, 2009)

Are you installing that at 240V or 208V? Odd nameplate.. If the max voltage is 253 then why use 208/230V.


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## joe-nwt (Mar 28, 2019)

Maybe that's a mis-print. I would call the manufacturer on that.


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## WronGun (Oct 18, 2013)

Dennis Alwon said:


> Are you installing that at 240V or 208V? Odd nameplate.. If the max voltage is 253 then why use 208/230V.


240v 

I thought it was odd, even the hvac tech pointed that out. 


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## VELOCI3 (Aug 15, 2019)

240.4B allows you to use 30 amp. The wire will be sized for min circuit ampacity on the nameplate. 


Wire will be #10 UF or 
#12 THHN

75 degree terminals

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## gpop (May 14, 2018)

Dennis Alwon said:


> Are you installing that at 240V or 208V? Odd nameplate.. If the max voltage is 253 then why use 208/230V.


That may be the true upper limit as anything higher would cause the inverter to shut down


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## MotoGP1199 (Aug 11, 2014)

VELOCI3 said:


> 240.4B allows you to use 30 amp. The wire will be sized for min circuit ampacity on the nameplate.
> 
> 
> Wire will be #10 UF or
> ...



I could be wrong but I always thought 440.22 (c) superseded 240.4B and would not allow you to go above the manufacturers maximum rating of OCPD. In this case the rating plate states max fuse "25 amps". I would normally do it similar to what Dennis suggested and put a 30 GFCI breaker (if needed) and then put a 25 amp OCPD inline somewhere.

"440.22 (c)
(C) Protective Device Rating Not to Exceed the Manufacturer’s Values. Where maximum protective device ratings shown on a manufacturer’s overload relay table for use with a motor controller are less than the rating or setting selected in accordance with 440.22(A) and (B), the protective device rating shall not exceed the manufacturer’s values marked on the equipment.
"


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## Dennis Alwon (May 9, 2009)

VELOCI3 said:


> 240.4B allows you to use 30 amp. The wire will be sized for min circuit ampacity on the nameplate.
> 
> 
> Wire will be #10 UF or
> ...



I don't believe 240.4(B) can overrule the manufacturers nameplate


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## just the cowboy (Sep 4, 2013)

Dennis Alwon said:


> Are you installing that at 240V or 208V? Odd nameplate.. If the max voltage is 253 then why use 208/230V.


208/230v rating times +-10% is 187min 253 max


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## oldsparky52 (Feb 25, 2020)

Dennis Alwon said:


> Are you installing that at 240V or 208V? Odd nameplate.. If the max voltage is 253 then why use 208/230V.


Since the min voltage was 187 I just thought it had a wide range of operation.


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## Dennis Alwon (May 9, 2009)

Yes but is it compliant to hook it to a 240V system? I think not. @WronGun


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## splatz (May 23, 2015)

They make dead front GFCIs rated for 30A but they're really expensive.


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## Dennis Alwon (May 9, 2009)

splatz said:


> They make dead front GFCIs rated for 30A but they're really expensive.


Are they 240V??


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## emtnut (Mar 1, 2015)

The nameplate may be messed up, agree with @joe-nwt to call mfr.

Since they say 208/230 , that is for 208 or EU 230 volts.
Motors are generally rated in utilization volts, so 208/240 is 200/230 on the nameplate.
Some name plates don't use utilization, and they just say 208 or 240 V

This one seems to be 208V US or 230V EU


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## Kevin (Feb 14, 2017)

All this talk about nameplate data. Here's a nameplate from an outdoor condenser. I thought it was odd it was wired with #8 teck so I snapped a photo so I could read the nameplate. Made sense after I read it.

Notice the voltages are identical?

They're likely using the old system voltages for their ratings. There was a time when everyone said 115/230 volts rather than the 120/240 we call it today...


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## splatz (May 23, 2015)

Dennis Alwon said:


> Are they 240V??


GFHW23005 | Hubbell


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## Bird dog (Oct 27, 2015)

Kevin said:


> All this talk about nameplate data. Here's a nameplate from an outdoor condenser. I thought it was odd it was wired with #8 teck so I snapped a photo so I could read the nameplate. Made sense after I read it.
> 
> Notice the voltages are identical?
> 
> They're likely using the old system voltages for their ratings. There was a time when everyone said 115/230 volts rather than the 120/240 we call it today.


IIRC in the NEC it states the system voltages to be used and are nominal (in name only). My understanding is the 115/230 on equipment takes into account voltage drop (or maybe that's just motors).
NEC 2014 Art 100 Def. pg 35 Voltage, Nominal


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## Dennis Alwon (May 9, 2009)

Kevin said:


> All this talk about nameplate data. Here's a nameplate from an outdoor condenser. I thought it was odd it was wired with #8 teck so I snapped a photo so I could read the nameplate. Made sense after I read it.
> 
> Notice the voltages are identical?
> 
> They're likely using the old system voltages for their ratings. There was a time when everyone said 115/230 volts rather than the 120/240 we call it today...



It has 208/230. not 115/230 so my opinion is that the unit is not rated for 240v-- assuming he is not from the great white north


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## gpop (May 14, 2018)

Dennis Alwon said:


> It has 208/230. not 115/230 so my opinion is that the unit is not rated for 240v-- assuming he is not from the great white north



Interesting especially as i have never seen a motor data plate that says 240v or 480v its always 208/230/460


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## Kevin (Feb 14, 2017)

gpop said:


> Interesting especially as i have never seen a motor data plate that says 240v or 480v its always 208/230/460


I have never seen a motor with anything different than those.

@Dennis Alwon our 600 volt motors up here are plated as 575 volts...


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## joe-nwt (Mar 28, 2019)

*Compressor . . . . . . . . . . . . . . . . . . . . . . . DC Inverter-driven Rotary*

Maybe that explains the wide input voltage.


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## emtnut (Mar 1, 2015)

I still think that 208/230V is weird.

208V motor will have 200V on the nameplate, and a 240V motor will have 230V. Motors are spec'd in utilization voltage.
Maybe this is an HVAC thing ? If it can be used on a 208V system, it should be 200V.


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## micromind (Aug 11, 2007)

It's pretty common for HVAC stuff to be nameplates at 208/230. Tons of motors have this designation as well. The two 3Ø units that I installed at my house 24 years ago are 208/230.

It's also very common to see the min voltage as 187 and the max at 253. 

As for the breaker tripping, this unit has a VFD to control the compressor. There's a good chance it'll never work with a GFI. Most VFDs won't.


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## eddy current (Feb 28, 2009)

Does the 2020 NEC have you guys GFI protect every circuit in a dwelling?


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## Forge Boyz (Nov 7, 2014)

eddy current said:


> Does the 2020 NEC have you guys GFI protect every circuit in a dwelling?


Not quite yet. That is the next code cycle I think. Then they will come up with something else to make the breakers even more expensive.

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## Forge Boyz (Nov 7, 2014)

Well well. Lookie here.









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## yankeejoe1141 (Jul 26, 2013)

Just GFCI the main breaker in the house and be done with it.


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## Kevin (Feb 14, 2017)

yankeejoe1141 said:


> Just GFCI the main breaker in the house and be done with it.


Problem with that is the nuisance tripping. a Class A GFCI trips with +/- 5ma of leakage... if you do GFCI for each circuit, you can have 2ma of leakage on each circuit without any issues, but with it on the main, that 2ma adds up and BOOM, now you're in the dark in the whole house. No lights. I hope you weren't doing something that you can get hurt doing in the dark (perhaps cutting something in the kitchen, or maybe cutting something with a saw in the garage?).


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## yankeejoe1141 (Jul 26, 2013)

Kevin said:


> Problem with that is the nuisance tripping. a Class A GFCI trips with +/- 5ma of leakage... if you do GFCI for each circuit, you can have 2ma of leakage on each circuit without any issues, but with it on the main, that 2ma adds up and BOOM, now you're in the dark in the whole house. No lights. I hope you weren't doing something that you can get hurt doing in the dark (perhaps cutting something in the kitchen, or maybe cutting something with a saw in the garage?).


Oh I'm not really advocating for that, I just feel like that's the direction it's going. There's really not going to be a whole lot left that's not GFCI protected.


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## Dennis Alwon (May 9, 2009)

Forge Boyz said:


> Well well. Lookie here.
> 
> Sent from my SM-G970U using Tapatalk


Did you post this in the wrong thread... Yes I am a member at Mike Holt's also...


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## Forge Boyz (Nov 7, 2014)

Dennis Alwon said:


> Did you post this in the wrong thread... Yes I am a member at Mike Holt's also...


It's the right thread. If you look at my comment right above that post I said that GFCI'S everywhere are coming in the next code cycle, which was kind of just a guess.. And then I went to Mike Holts and read that.

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## Dennis Alwon (May 9, 2009)

Gotcha, I was wondering where that came from....


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## VELOCI3 (Aug 15, 2019)

Dennis Alwon said:


> I don't believe 240.4(B) can overrule the manufacturers nameplate


I forgot about that. Good catch. 


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## WronGun (Oct 18, 2013)

I ordered a standard 25A breaker and will put a 2 space box outside with gfci 30A


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## gpop (May 14, 2018)

Kevin said:


> Problem with that is the nuisance tripping. a Class A GFCI trips with +/- 5ma of leakage... if you do GFCI for each circuit, you can have 2ma of leakage on each circuit without any issues, but with it on the main, that 2ma adds up and BOOM, now you're in the dark in the whole house. No lights. I hope you weren't doing something that you can get hurt doing in the dark (perhaps cutting something in the kitchen, or maybe cutting something with a saw in the garage?).


At least 100 million homes are using a main 30ma rcd that will trip around 15ma. Most are also using them on higher voltages with out having a problem.

Give a 5ma gfci in the bathroom and one next to the kitchen sink and let the rcd take care of the rest of the house. Whole area's have power cuts with no warning and the hospitals are not full of accidents due to this so its a weak argument.


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## VELOCI3 (Aug 15, 2019)

WronGun said:


> I ordered a standard 25A breaker and will put a 2 space box outside with gfci 30A
> 
> 
> Sent from my iPhone using Tapatalk


What about a 30A gfi breaker in the panel to a fused disconnect by the unit with 25A one time fuses


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## yankeejoe1141 (Jul 26, 2013)

VELOCI3 said:


> What about a 30A gfi breaker in the panel to a fused disconnect by the unit with 25A one time fuses
> 
> 
> Sent from my iPhone using Tapatalk


But then would you have to run a larger conductor for the 30 amp OCPD?


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## VELOCI3 (Aug 15, 2019)

yankeejoe1141 said:


> But then would you have to run a larger conductor for the 30 amp OCPD?


I would run #10. You might get an inspector that doesn’t know you can do that. Eg 2 wires in a square D breaker. 


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## WronGun (Oct 18, 2013)

I already ran 12, I rather not change as long as it’s code.

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## Bird dog (Oct 27, 2015)

WronGun said:


> I already ran 12, I rather not change as long as it’s code.
> 
> Sent from my iPhone using Tapatalk


According to the nameplate minimum ckt ampacity is 21amps, so, minimum would be a #10? Or would the 75 degree column allow a #12?


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## micromind (Aug 11, 2007)

#12 for 21 amps is fine for HVAC. 

240.4(D) states that unless specifically permitted in 240.4(E) or 240.4(G), the overcorrect protection shall not exceed 15 amps for #14, 20 amps for #12 and 30 amps for #10. 

Table 240.4(G) specifically states air-conditioning and refrigeration circuit conductors therefore, the 20 amp limit on #12 does not apply.


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## yankeejoe1141 (Jul 26, 2013)

micromind said:


> #12 for 21 amps is fine for HVAC.
> 
> 240.4(D) states that unless specifically permitted in 240.4(E) or 240.4(G), the overcorrect protection shall not exceed 15 amps for #14, 20 amps for #12 and 30 amps for #10.
> 
> Table 240.4(G) specifically states air-conditioning and refrigeration circuit conductors therefore, the 20 amp limit on #12 does not apply.


But if you run romex then aren't you limited to the 60 degree column and #12 is only rated for 20 amps at 60 deg, then you would have to go to #10.


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## micromind (Aug 11, 2007)

yankeejoe1141 said:


> But if you run romex then aren't you limited to the 60 degree column and #12 is only rated for 20 amps at 60 deg, then you would have to go to #10.


I believe so. As far as I know, there are no exceptions to the 60C rule for NM cable.


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## VELOCI3 (Aug 15, 2019)

yankeejoe1141 said:


> But if you run romex then aren't you limited to the 60 degree column and #12 is only rated for 20 amps at 60 deg, then you would have to go to #10.













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## micromind (Aug 11, 2007)

334.80 The ampacity shall be in accordance with the 60ºC conductor temperature rating. 

I don't know if 240.4(G) would overrule or not but I doubt it would.


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## yankeejoe1141 (Jul 26, 2013)

micromind said:


> 334.80 The ampacity shall be in accordance with the 60ºC conductor temperature rating.
> 
> I don't know if 240.4(G) would overrule or not but I doubt it would.


I don’t think it does. I think you can use the higher ratings as a starting point for de-rating but the final ampacity can’t exceed the 60 deg column. 

So if there’s romex in any portion of the circuit that portion is technically limited to 20 amps, since he said he already ran #12.


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## Sean j (Feb 27, 2021)

WronGun said:


> I recently wired a Mitsubishi heat pump.
> 
> Min circuit ampacity 21 amps, Max OCPD 25amp
> 
> ...


Amazon


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## d2043 (Nov 12, 2013)

WronGun said:


> I recently wired a Mitsubishi heat pump.
> 
> Min circuit ampacity 21 amps, Max OCPD 25amp
> 
> ...


Put a regular 25 amp breaker on it and don't worry about it


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## d2043 (Nov 12, 2013)

Sean j said:


> Amazon


they do make them.


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## Dennis Alwon (May 9, 2009)

yankeejoe1141 said:


> But then would you have to run a larger conductor for the 30 amp OCPD?


I already stated to use a 30 amp gfci at the unit and a 25 amp standard breaker at the panel.


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## VELOCI3 (Aug 15, 2019)

Dennis Alwon said:


> I already stated to use a 30 amp gfci at the unit and a 25 amp standard breaker at the panel.


Fused 30a disco with 25A one time fuses if cheaper or more available than the breaker setup. 


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## Dennis Alwon (May 9, 2009)

VELOCI3 said:


> Fused 30a disco with 25A one time fuses if cheaper or more available than the breaker setup.
> 
> 
> Sent from my iPad using Tapatalk


I thought he wanted gfci protection


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## Dennis Alwon (May 9, 2009)

Not sure why he wants gfci protection. Right now there is a TIA out to wave the 2020 requirement for gfci on a/c units until 2023. Apparently they cannot get gfci to work satisfactorily with the units as they are now designed.


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## Above Code (Apr 14, 2017)

WronGun said:


> I recently wired a Mitsubishi heat pump.
> 
> Min circuit ampacity 21 amps, Max OCPD 25amp
> 
> ...


How about installing a 30 A GFCI breaker and fusable disconnect fused at 25 amps


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## VELOCI3 (Aug 15, 2019)

Dennis Alwon said:


> I thought he wanted gfci protection


30 A GFCI- #10 romex or UF- 30A disconnect with 25A one time fuses- #12 thhn- compressor. Will provide ground fault, short circuit and over current. 


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## Dennis Alwon (May 9, 2009)

The op already ran #12 so why not install the 25 amp to protect the circuit from short circuit etc. and then install the 30 gfci at the unit-- this way there is no #10 involved


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