What size breaker and wiring needed for subpanel?

[popechild]

Our equipment pad is moving about 20' from where it had previously been and I'm replacing an old load center in the process. Previously there was a separately run 50a line from the main breaker for our heat pump, but all the original wiring (and heat pump line) were torn out during a renovation of the house.

The equipment will be:
- Pentair SuperFlo VS 1.5hp pump (13.6a max draw)
- Pentair Amerilite 500w watt 120v light (~4.2a, though this is very rarely ever used)
- CircuPool SJ30 SWG (.63a at 240v)
- AquaCal TropiCal T135 Heat Pump (43.3 Minimum Circuit Ampacity)
- Two 120v utility outlets (one at pad and one at light j-box)

I'm not planning an automation-capable panel, just a basic outdoor load center. Also, I haven't yet figured out what to do about freeze protection, so that may add a bit of draw. (I've had a separate old Freeze Defender hooked up that worked fine, but it's pretty rusty and I'm having trouble finding any similar standalone product now. Mostly seems like people either have pumps with temp sensors built in or have a timer with it, but I'm not planning a timer since I'll be using the VS pump to schedule things.)

The house's new main outdoor box has an empty 1.5" conduit running to the new pad location and 4 empty breaker slots in it.

If I run a single breaker and line to the sub-panel, I'm thinking I'd need something like an 80a breaker and 4/3 copper? But 4 gauge doesn't seem to be readily available.

Would I be better off running two separate smaller lines through the same conduit? Like a 50a breaker on 6/3 direct to the heat pump and a separate 8/3 line on a 40a breaker for everything else, with separate breakers at the load center (20a for Superflo, 15a for light/j-box outlet, 15a for pad utility outlet)?

The pad is within sight/distance requirements from the main box breaker to not need a separate cutoff at the pad, at least as I understand them.

I don't want to undersize things, but I also don't want to pay out the nose for larger wire than needed. It'll be about a 35' run.

Appreciate any thoughts or guidance. Thanks!

 

[Bperry]

Our equipment pad is moving about 20' from where it had previously been and I'm replacing an old load center in the process. Previously there was a separately run 50a line from the main breaker for our heat pump, but all the original wiring (and heat pump line) were torn out during a renovation of the house. My assumption is I'll want a single run to the new load center and I'm trying to make sure I size everything right.

The equipment will be:
- Pentair SuperFlo VS 1.5hp pump (13.6a max draw)
- Pentair Amerilite 500w watt 120v light (~4.2a, though this is very rarely ever used)
- CircuPool SJ30 SWG (.63a at 240v)
- AquaCal TropiCal T135 Heat Pump (43.3 Minimum Circuit Ampacity)
- Two 120v utility outlets (one at pad and one at light j-box)

I'm not planning an automation-capable panel, just a basic outdoor load center. Also, I haven't yet figured out what to do about freeze protection, so that may add a bit of draw. (I've had a separate old Freeze Defender hooked up that worked fine, but it's pretty rusty and I'm having trouble finding any similar standalone product now. Mostly seems like people either have pumps with temp sensors built in or have a timer with it, but I'm not planning a timer since I'll be using the VS pump to schedule things.)

The house's new main outdoor box has an empty 1.5" conduit running to the new pad location and 4 empty breaker slots in it. I suppose I could run two separate smaller wires through the same conduit off of two breakers, one for the heat pump and one for everything else, but my assumption has been I'd run one breaker and one wire to the load center. Would an 80a breaker and 4/3 wire be the right combo here? Then separate breakers at the load center (50a for heat pump, 20a for Superflo, 15a for light/j-box outlet, 15a for pad utility outlet)? The pad is within sight/distance requirements from the main box breaker to not need a separate cutoff at the pad, at least as I understand them.

I don't want to undersize things, but I also don't want to pay out the nose for larger wire than needed. It'll be about a 35' run.

Appreciate any

The breaker size is dependent on the wire size and is generally required to be sized at 80% of the load capacity of the wire. So 80A breaker protects wire rated to handle 100A.

The wire gauge isn’t necessarily dependent on what you “plan” to be running at the same time. It’s required to safely carry everything that “can be” turned on plus an extra 20% buffer.

Do your two outlets need separate breakers by law? You might see if you can put them both on the same 15A breaker unless you plan to permanently power a piece of equipment with one of them. That drops your overall current budget a bit.

 

[popechild]

I don't honestly know if the two outlets need to be on separate breakers. Previously there was just a single breaker running to the pool light, with a half-outlet/half-switch in the pool light's j-box. There wasn't a separate outlet at the pad, but the pad was just a few feet from the corner of the house where there was another outlet available. Now that the pad is moving, it's not close enough to any other outlets to use those as the required equipment utility outlet. But no, I don't know if I could run them both off the same breaker.

If I can, you're saying I could use a single 15a breaker for both outlets and the light, which would drop my overall breaker needs to 50a+20a+15a. I'm not clear on what impact that would have on the wire options I'd have available?

 

[Bperry]

I don't honestly know if the two outlets need to be on separate breakers. Previously there was just a single breaker running to the pool light, with a half-outlet/half-switch in the pool light's j-box. There wasn't a separate outlet at the pad, but the pad was just a few feet from the corner of the house where there was another outlet available. Now that the pad is moving, it's not close enough to any other outlets to use those as the required equipment utility outlet. But no, I don't know if I could run them both off the same breaker.

If I can, you're saying I could use a single 15a breaker for both outlets and the light, which would drop my overall breaker needs to 50a+20a+15a. I'm not clear on what impact that would have on the wire options I'd have available?

You might need to look up the applicable electrical code. I can run multiple 15A outlets on a single 15A breaker for my kitchen because the code assumes not all outlets are being used at the same time. There are special cases where an outlet needs its own breaker where a piece of equipment is dedicated to that outlet so you’ll need to figure out if that’s applicable. If it’s a general purpose outlet, it’s probably fine.

The overall impact is that your main feed line doesn’t need to accommodate 2 15A loads anymore and so that big wire run might drop you into a smaller (and cheaper) wire gauge and breaker.

I might look at running a big 80A breaker for 230V cable for just the heat pump and VS pump along with a separate wire run for the 120V items.

Maybe obvious, but figure out what wire you need to have first, then that will determine what breaker sizes are needed.

 

[guinness]

For standalone Freeze Protection you could get something like Intermatic PF1103 and use the relay for the SuperFlo digital inputs, see Installation And User’s Guide for details. Also you haven't mentioned GFCI protection, but current NEC specifies that one is needed for the pool pump (in addition to the pool light).

 

[popechild]

For standalone Freeze Protection you could get something like Intermatic PF1103 and use the relay for the SuperFlo digital inputs, see Installation And User’s Guide for details. Also you haven't mentioned GFCI protection, but current NEC specifies that one is needed for the pool pump (in addition to the pool light).

Yes, didn't mention it but pump and light breakers will be GFCI. Heat pump will not. Thanks for the lead on the Intermatic. I'll look into it.

 

[BMerrill]

Most jurisdictions will require a permit for your proposed work.
What you are doing can become complicated quickly as the NEC has requirements that affect wire size including degradation of the amp carrying capacity dependent upon the number of conductors in the conduit. Please consider hiring a licensed electrician to do this work.

Simple thought is to use an outdoor rated load center at the equipment pad as a subpanel with a main 100amp breaker in the subpanel as a disconnect. Use a 100 amp breaker in the main panel running #3 copper. Recommend a whole house surge in both panels. GFIC breaker on everything except the Heat pump. Only put the 15amp outlets on the same circuit, everything else on a separate breaker. Do not tie grounds and neutrals together in the subpanel. Very important!!!! Don't forget to move the bonding to the new location.

 

[ajw22]

You might need to look up the applicable electrical code. I can run multiple 15A outlets on a single 15A breaker for my kitchen because the code assumes not all outlets are being used at the same time. There are special cases where an outlet needs its own breaker where a piece of equipment is dedicated to that outlet so you’ll need to figure out if that’s applicable. If it’s a general purpose outlet, it’s probably fine.

 

[guinness]

If you decide to use the Intermatic PF1103 you might need an additional relay to isolate the low voltage wiring. Also worth mentioning that external digital inputs override scheduled speeds, i.e. if pump was already running at Speed 1 the digital input speed selected (if different) would then be used.

 

[popechild]

Most jurisdictions will require a permit for your proposed work.
What you are doing can become complicated quickly as the NEC has requirements that affect wire size including degradation of the amp carrying capacity dependent upon the number of conductors in the conduit. Please consider hiring a licensed electrician to do this work.

Simple thought is to use an outdoor rated load center at the equipment pad as a subpanel with a main 100amp breaker in the subpanel as a disconnect. Use a 100 amp breaker in the main panel running #3 copper. Recommend a whole house surge in both panels. GFIC breaker on everything except the Heat pump. Only put the 15amp outlets on the same circuit, everything else on a separate breaker. Do not tie grounds and neutrals together in the subpanel. Very important!!!! Don't forget to move the bonding to the new location.

Thanks for this. A couple of clarification questions.

One, when you say only the 15a outlets on the same circuit, what about the pool light? Prior to the renovation, there was a j-box with a combo outlet/switch for the pool light. Is that a bad idea? I don't necessarily still need that outlet, as the renovation has added a few other outlets within 20' of the pool in other places. So maybe it's best to scrap that one and just use that 120v GFCI-breakered line for the light?

Two, do I need a 100a breaker in the subpanel as a disconnect if my main panel is only 20' away on the same side of the garage as the pad? It seems like I don't, but are you suggesting it's just a good idea for the added convenience of not having to go 20' for that disconnect if/when needed?

 

[popechild]

Also BMerrill, absolutely hear you on the licensed electrician. I plan to have someone come look everything over and do the final connect to the main panel to verify it's good to go, but trying to get as much of the grunt work done myself so his workload (and bill) is minimal.

 

[BMerrill]

One, when you say only the 15a outlets on the same circuit, what about the pool light? Prior to the renovation, there was a j-box with a combo outlet/switch for the pool light. Is that a bad idea? I don't necessarily still need that outlet, as the renovation has added a few other outlets within 20' of the pool in other places. So maybe it's best to scrap that one and just use that 120v GFCI-breakered line for the light?

Two, do I need a 100a breaker in the subpanel as a disconnect if my main panel is only 20' away on the same side of the garage as the pad? It seems like I don't, but are you suggesting it's just a good idea for the added convenience of not having to go 20' for that disconnect if/when needed?

Keep the pool light separate. If the light goes down, you don't want to lose power to the outlets. For the outlets, if you keep them, use a GFIC outlet at each location instead of a GFIC breaker. If an outlet goes bad, you still have the others on the same circuit. Suggest an outlet near the pool equipment if you don't have one. Comes in handy for portable work lighting.

I'm a advocate for having a main disconnect in each panel even if the panels are side by side.