What breaker do I need for a ductless mini split compressor?

[Xcel]

I am getting conflicting info on what I will need for a panel breaker for a ductless mini split. I have provided the link to the spec sheet for the compressor. The fuse is installed and just need to run wire to panel and install breaker. The current AC that will be trashed has dual 20 amp breakers Compressor Spec Sheet

 

[Xcel]

I am a demo contractor, to make a long story short I need to have this system installed. Only thing left running electrical to the unit. Want to make sure it is done right and the two subs I brought in have very different thoughts on what needs to be done.

 

[electrofelon]

Looks like you need 30A Conductors, so #10. According to the spec sheet you will need to use a fuse and not a circuit breaker. If you can look at the actual unit it may say fuse or circuit breaker. You could use a fused disconnect at the unit in a 30 amp breaker in the panel should do it.

 

[Xcel]

Yes, there are 45amp fuses installed at the compressor but the issue seems to be that the condo unit has only 40amp breaker at the main panel. So I believe a we need a higher gauge wire from the main panel to the sub-panel and a change in the main breaker. The run is 150ft

 

[ritelec]

I am getting conflicting info on what I will need for a panel breaker for a ductless mini split. I have provided the link to the spec sheet for the compressor. The fuse is installed and just need to run wire to panel and install breaker. The current AC that will be trashed has dual 20 amp breakers Compressor Spec Sheet

Just.... lol


2 pole 20 being trashed, 45 amp fuses, 40 amp breaker??? Believe you need higher gauge wire?

I would think you should ask your electrician.

 

[texie]

Yes, there are 45amp fuses installed at the compressor but the issue seems to be that the condo unit has only 40amp breaker at the main panel. So I believe a we need a higher gauge wire from the main panel to the sub-panel and a change in the main breaker. The run is 150ft

You need conductors with an ampacity of 30 amps. The OCPD needs to be 45 amp. The OCPD does not need to match the ampacity of the conductors in this application. If it is already installed with #10 conductors just simply change the breaker to 45 amp and install a 60 amp disconnect with 45 amp fuses to meet the requirement of fuses only per the spec sheet.

 

[Eddie702]

Agree with @texie. This is a motor circuit. The wire is allowed to be protected above its ampacity.

The spec sheet says "MFA"=Maximum fuse allowed 45

and "MCA"= minimum circuit amps 30

On a long run you might want to upsize the wire to #8s for the voltage drop

 

[norcal]

Agree with @texie. This is a motor circuit. The wire is allowed to be protected above its ampacity.

The spec sheet says "MFA"=Maximum fuse allowed 45

and "MCA"= minimum circuit amps 30

On a long run you might want to upsize the wire to #8s for the voltage drop

Then NM cable could not be used, since the grounding conductor would need to be upsized.

 

[LarryFine]

The OCPD needs to be 45 amp.

Actually, it could be lower as long as the compressor reliably starts on it.

 

[Eddie702]

@norcal

If they run #10s it would have a #10 equipment ground which is ok up to 60 amps.

@LarryFine as long as it starts on the smaller breaker yes (in this case fuse protection) MOCP is Maximum over current protection as you pointed out

 

[norcal]

@norcal

If they run #10s it would have a #10 equipment ground which is ok up to 60 amps.

@LarryFine as long as it starts on the smaller breaker yes (in this case fuse protection) MOCP is Maximum over current protection as you pointed out

My comment was directed to your #7 post, if you upsize the ungrounded conductor, upsizing the grounding conductor is required, with 8 AWG NM cable the EGC is 10AWG which would not be compliant in that situation because of increasing the size to 8 AWG. See 250.122(B).

 

[sdbob]

I have yet to see one of these installed that meets code. I've NEVER seen a disconnect inside at the condenser. Do they have super special immunity from NEC 430.102? Almost always see some kind of flexible SO cord between compressor and condenser duck taped to the refrigerant lines. It's like they're installed by Mitsubishi code, not the NEC. It's been a while since I posted here, but I couldn't help myself... pet peeve. It's like double switched light fixtures with 3-way switches wired in MC. See them everywhere, almost all are wired wrong.

 

[electrofelon]

I have yet to see one of these installed that meets code. I've NEVER seen a disconnect inside at the condenser. Do they have super special immunity from NEC 430.102? Almost always see some kind of flexible SO cord between compressor and condenser duck taped to the refrigerant lines. It's like they're installed by Mitsubishi code, not the NEC. It's been a while since I posted here, but I couldn't help myself... pet peeve. It's like double switched light fixtures with 3-way switches wired in MC. See them everywhere, almost all are wired wrong.

There is a reasonable argument that the indoor unit is covered by article 422 in which case a remote lockable disconnect would be acceptable. Actually nearly all places I work require and enforce a disconnect for the indoor unit. The TC ER cable often used is acceptable in many jurisdictions, and is permitted in 1 and 2 family dwellings since NEC 2017 336.10

 

[hbiss]

I've NEVER seen a disconnect inside at the condenser.

Many locations do not require them. The outside disconnect covers it. I have never installed one.

Almost always see some kind of flexible SO cord between compressor and condenser duck taped to the refrigerant lines.

That's TC ER cable.

-Hal

 

[sdbob]

Honestly I'm not familiar with the United States but California... even the mechanical code requires it. Ca mech code 903.2.7 and CEC CEC 440.14 .

I wasn't aware that cable was permitted in family dwellings, my universe is commercial. Regardless I can't see Gorilla tape with the refrigerant lines considered support.

 

[electrofelon]

Regardless I can't see Gorilla tape with the refrigerant lines considered support.

Why not? Do you have a code reference?

 

[kwired]

There is a reasonable argument that the indoor unit is covered by article 422 in which case a remote lockable disconnect would be acceptable. Actually nearly all places I work require and enforce a disconnect for the indoor unit. The TC ER cable often used is acceptable in many jurisdictions, and is permitted in 1 and 2 family dwellings since NEC 2017 336.10

I don't think there is any argument at all. It is not a 440 application because it doesn't contain a hermatic refrigerant compressor, it is not a "motor" so 430 doesn't apply, it is a motor operated appliance, so you start in 422 and only go to specific 430 sections for any aspect that 422 might send you there for.

These are nearly always less than 300 VA or 1/8 HP, though that doesn't really change the requirements and I don't know why they continue to keep wordage of that type in the code. At one time I don't think it would have required the locking provisions if not in sight but more recently it does and seems to now have same requirement above as it does below 300VA or 1/8 HP.