Wiring for minisplits

[1jeepfan]

Need some help here. I’m having two minisplits installed next week. I have to run the wiring for them. The installer gave me the specs for the units. The biggest unit lists the ‘MOCP’ as 40 amps. Is that what I need to size the breaker and wiring for?

 

[Stuff]

MOCP is breaker size. MCA is for wire size so you need more information.

 

[1jeepfan]

Ok. It says the MCA is 24. What does that tell me?

 

[Stuff]

You need wire to handle 24 amps. 10 gauge copper goes to 30 amps. So get 10/2 NM cable.

 

[1jeepfan]

Thank you!!

 

[1jeepfan]

It's for 208/230. So 10/3?

 

[MattT]

It's for 208/230. So 10/3?

It's probably two wire but check your docuentation to be sure.

 

[Highbeam]

It's okay to have an extra white unused. I would run 10/3 which is only slightly more expensive.

 

[1jeepfan]

Yeah, I read the installation instructions online, and they call for a neutral wire. So I guess 10/3 it is!

Thanks.

 

[raco232]

With a 40A breaker, you need to be using 8 gauge wire. 10 gauge wire is only good for up to a 30 amp breaker.

 

[Stuff]

With a 40A breaker, you need to be using 8 gauge wire. 10 gauge wire is only good for up to a 30 amp breaker.

There are exceptions and HVAC equipment is covered by one of them.

 

[inphx]

Outside terminate the wires in an AC disconnect box and from there would be a flexible "whip" to the condenser. If you are concerned with code i believe there may be a need for an AC outlet within 25' to service the appliance... there are disconnect boxes that include an outlet.

Sounds like your installer will account fro the Freon lines and low voltage cables to the unit and condensate drain out of it.

 

[raco232]

There are exceptions and HVAC equipment is covered by one of them.

Thank you, I was not aware of the exceptions.

 

[Norcal]

It's okay to have an extra white unused. I would run 10/3 which is only slightly more expensive.

It is wasting money to run a neutral for a 240 volt appliance, if you have money to squander, go right ahead.

With a MCA of 24, & MOCP of 40, 10/2 NM, & a 40A breaker is fine, if conduit is used 12 gauge THWN & a 40A breaker is still code compliant, rules for HVAC are different then for branch circuits, w/ HVAC, you wire for the minimum, & use the maximum fuse or circuit breaker listed on the equipment data plate.

 

[1jeepfan]

I definitely don’t like to waste money (on stuff like this). The 10/3 I used for something else was twice the price of 10/2. I think I have enough 10/3 left over to make this run though.

 

[Norcal]

I definitely don’t like to waste money (on stuff like this). The 10/3 I used for something else was twice the price of 10/2. I think I have enough 10/3 left over to make this run though.

If the wire is leftover from another job, then it's not wasting money.