What size breaker to feed sub

[mike93lx]

This is for a subpanel to feed pool equipment.

Heat pump - 240v, 42.1a minimum circuit ampacity, 60a max breaker
Pump - 1.8hp variable speed. Dual voltage, assume 240v
Salt chlorinator - 2a, 120v
Service outlet - 15a? 120v
Feed to pool shed - 20a MWBC

Whenever the HP is running, the pump will also be running. The service outlet will almost never get used, but even if it does, I'd expect minimal load. I don't have anything really heavy draw that will go in the shed, other than a EGO battery charger (750w) and a mini fridge.

Feels to me like 80-90a would be prudent.

An electrician is doing the work, I just want to be know what to expect/push for, if needed. Everything is standard to their work except the shed wiring

 

[Terry D]

I would not go less than a 90 amp. #2 aluminum

 

[mike93lx]

Not less than... Would larger be appropriate?

 

[Terry D]

Not less than... Would larger be appropriate?

In most cases, I personally never put in anything less than a 100 amp sub, but here we are allowed to use #2 aluminum for 100 amp for a dwelling. They consider a outbuilding an extension of the dwelling. But I am aware it is not like that in all parts of the country. Its just a common thing here, 1 1/4 PVC and (3) #2 XHHW's and (1) #6 XHHW for 100 amps, but depending on your codes, you might have to use a 90 amp breaker to feed it. The sub that you are going to put out there will be a 100 amp panel, you could bump the wire size up to #1 and still use the same size conduit and get the full 100 amps out there. I always like to have a little extra for future.

 

[mike93lx]

I personally never put in anything less than a 100 amp sub, but here we are allowed to use #2 aluminum for 100 amp for a dwelling. They consider a outbuilding an extension of the dwelling. But I am aware it is not like that in all parts of the country. Its just a common thing here, 1 1/4 PVC and (3) #2 XHHW's and (1) #6 XHHW for 100 amps, but depending on your codes, you might have to use a 90 amp breaker to feed it. The sub that you are going to put out there will be a 100 amp panel, you could bump the wire size up to #1 and still use the same size conduit and get the full 100 amps out there. I always like to have a little extra for future.

this will be an outdoor sub, located at the pool equipment as the shed is over 100' away. I can't imagine what I would add at that location that would necessitate additional capacity, and ultimately, I could just run a dedicated feed from the main panel if that happens (its under 20').

I do want to make sure that I have a pair of open slots in the sub, just in case.

i'm not sure if I'd be able to use a 100a breaker to feed it, i can ask when the electrician is out

 

[75gmck25]

Many locations only allow 90 amps on 2-2-2-4 AL wire (SER or MHF is often used), so you would use a 90 amp breaker in the main panel.

MHF is very common and therefore usually cheaper than most other choices for 90 amps. It can be run underground in conduit or direct buried, but inside a dwelling it must be in conduit up to the panel. You could use a 90 amp breaker in the main panel and the 100 amp breaker in the sub-panel would serve as a disconnect. 100 amp sub-panels are available that will support up to 24 circuits, but 8-16 are more common.