Need Confirmation on Breaker Size and Wire Gauge for Heat Pump Installation

M

mirx

Member
Location
Halifax, NS, CAN
Occupation
Apprentice Electrician
Hi everyone,

I'm getting ready to install a new heat pump and need some guidance on the correct breaker size and wire gauge for the setup.
Here are the specs:
  • Minimum Circuit Ampacity: 40.0A
  • Max Fuse: 60.0A
  • Wire Run Length: Approximately 40 feet from the panel to the outside box
From my understanding, the breaker size should be in line with the minimum circuit ampacity, but I'm a bit unsure about the exact specifications. Additionally, I want to ensure that I use the correct wire gauge to safely handle the load over the 40-foot run.

Based on what I’ve researched so far:
  • For a 40A minimum circuit ampacity, a 40A or 60A breaker might be appropriate
  • Considering the wire run length, it seems like 8 AWG wire might be suitable, but I want to confirm this is safe and meets code requirements.
Can anyone with experience in HVAC installations or electrical work provide some insights or confirm if I'm on the right track? Any advice would be greatly appreciated!
Thanks in advance for your help!

https://imgur.com/a/Ldw8Auk
 
Welcome to the forum.

mirx said:
  • Minimum Circuit Ampacity: 40.0A
Click to expand...
That dictates minimum wire size, not over-current protection.

mirx said:
  • Max Fuse: 60.0A
Click to expand...
That indicates maximum over-current protection. Fuse means not a breaker.

mirx said:
  • Wire Run Length: Approximately 40 feet from the panel to the outside box
Click to expand...
That's not an abnormal distance at all.


The usual installation would be a 60a breaker feeding a 40a wiring method and 60a fuses in the disconnect.
 
Thank you for the clarification!
So, it will be: a 60A fused disconnect switch near the heat pump.

Given the minimum circuit ampacity is 40A and the maximum fuse rating is 60A, what would a the appropriate breaker size in the panel?
 
I'm guessing that a new unit in 2024 does not require fuses. Before I would install a fused disconnect I would contact the company for clarification.
 
infinity said:
I'm guessing that a new unit in 2024 does not require fuses. Before I would install a fused disconnect I would contact the company for clarification.
Click to expand...
I just called the Manufacturer, they said: they don't require a disconnect box, they consider it jurisdictional.
If I do use one, match the size of breaker and the fused disconnect.
 
mirx said:
I just called the Manufacturer, they said: they don't require a disconnect box, they consider it jurisdictional.
If I do use one, match the size of breaker and the fused disconnect.
Click to expand...
So are fuses required or are they optional?
 
mirx said:
I just called the Manufacturer, they said: they don't require a disconnect box, they consider it jurisdictional.
If I do use one, match the size of breaker and the fused disconnect.
Click to expand...

The question is if the unit is only rated for 60A _fuses_, or if a 60A breaker is acceptable for providing overcurrent protection.

Because the label says 60A _fuse_, unless you have documented clarification from the manufacturer you are required to use a fuse, even though in reality a breaker is probably fine.

Usually the label will say 'Max OCPD 60A' not 'Max FUSE 60A'

-Jonathan
 
What @winnie said is accurate. While it is true that Most units can use breaker or fuses you do not in all cases have that choice.

If the name plate says fuses then you need fuses.

And the nameplate above strictly says fuses. If the inspector follows the NEC you need fuses
 
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