Purr24
Member
- Location
- Pennsylvania
- Occupation
- Electrician
Can I run the feeder for the outdoor unit in the same conduit with the indoor unit? Outdoor unit feeds the indoor unit. Thanks
Split AC unit
- Thread starter Purr24
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Beaches EE
Senior Member
- Location
- NE Florida
- Occupation
- Electrical Engineer / Facilities Manager
Can you provide more details about the installation such as residential or commercial, location of the units, wiring methods, mini-split or traditional heat pump / condensing unit with an indoor air handler?
curious as to why you ask. Under what conditions whould the answer be other than "yes": ?
Beaches EE
Senior Member
- Location
- NE Florida
- Occupation
- Electrical Engineer / Facilities Manager
Two reasons, mainly because I am curious and like to have some facts before providing input 
and the other relates to the variety of questions about the cable used to interconnect the units in mini-split systems.
and the other relates to the variety of questions about the cable used to interconnect the units in mini-split systems.
- Location
- Bremerton, Washington
- Occupation
- Master Electrician
Location doesn't matter, to the OP there is no general restriction, however, you need to consider wire fill, derating, etc,
Last edited:
Purr24
Member
- Location
- Pennsylvania
- Occupation
- Electrician
It is a condensing unit on the roof and air handler in data center. Condensing unit is 2#8 &1#10grnd. 40 amps 208v and this feeds the indoor air handler w/ 3-#12thhn.I need to run pipe in a 4 story shaft to the roof and want to run everything in one 1"EMT is this legal?
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- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
I didn't do the math but yes you can run both in the same conduit
- Location
- Bremerton, Washington
- Occupation
- Master Electrician
1. Look at wire fill, 2 #8s, 1 #10, and 3 #12s in a 1" EMT
2. You have 4 CC conductors, need to adjust ampacity for more than 3.
Pretty basic for an electrican, let us know what you come up with and we can check
2. You have 4 CC conductors, need to adjust ampacity for more than 3.
Pretty basic for an electrican, let us know what you come up with and we can check
Purr24
Member
- Location
- Pennsylvania
- Occupation
- Electrician
Correct me if I'm wrong been a while.
#8 THHN is rated for 55amps at 90 degrees
4-6 conductors is derate at 80 percent
55 X .80= 44amps
I will install on a 40 amp breaker
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#8 THHN is rated for 55amps at 90 degrees
4-6 conductors is derate at 80 percent
55 X .80= 44amps
I will install on a 40 amp breaker
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- Location
- Bremerton, Washington
- Occupation
- Master Electrician
Ok and your #12 derate from 30 amps. If on a 20 amp CB then OK
Wire fill, my guess is its OK
Wire fill, my guess is its OK
Purr24
Member
- Location
- Pennsylvania
- Occupation
- Electrician
Thanks! should be fine using 1" Emt
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kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
Where does your 40 amps come from? If MCA then you are likely on right track, if it is MOCP there is a fairly good chance MCA is enough less that you possibly can use 10 AWG. Would need a MCA of no more than 32 if you also have adjustment factor of 80%.
Then comes the air handler conductors. If no heat strips are involved many those only draw 2-3 amps max and would be fine on 14 AWG, even after ampacity adjustments in nearly all cases.
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