adding a heat pump to pool - subpanel questions

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  #1  
Old 04-12-14, 08:39 PM
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adding a heat pump to pool - subpanel questions

current setup - 200 amp main panel in basement feeding a 50amp sub panel in a detached poolhouse running on #4 copper. then from the poolhouse sub it goes on to a pool equipment subpanel that is mounted to the outside back wall of the poolhouse (#10 copper). the pool subpanel feeds a variable speed pump (max 16 amp), propane pool heater (not much current), pool light and some other small items like a salt water generator - but not much draw.

since the pool equipment subpanel only has 30 amps feeding it and the pool heat pump takes a minimum circuit of 35 amps i'll never have enough juice when the pump and heat pump are running (or pump is running and heat pump starts).

i do have 1.5 inch conduit run separately to the pool equipment area with #2 aluminum cable that i was going to use for a generator line but changed plans so it is unused now. so i have a couple options, what should i do?

option 1 use existing pool sub panel and pull larger wire from the poolhouse sub. i believe that the #4 copper from the main house to the poolhouse subpanel can handle 70 amps (it's about 80 ft away). so i can try to replace the #10 wire from the poolhouse sub to the pool equipment sub with say #6 which would allow me to put a 50 amp breaker on it and probably just make it as far as available amperage. problem is that it is in conduit and runs under some concrete with turns so this may be too hard.

option 2 run a separate line off the poolhouse sub to a new subpanel at the pool equipment. but not sure if i can have 2 subpanels at the equipment pad?

i dont think i can use the #2 aluminum cable in conduit because the ground is not insulated and i'm not sure that i can have 2 subpanels at the equipment pad either. if it is ok to have 2 subpanels since it is not in a building i could pull the aluminum cable out and drop something with a shielded ground in the 1.5" conduit. bit of a pain as i'll have to dig up cause no way i can just pull it out from one end.

anyway, thought would be much appreciated.

thanks in advance
 
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  #2  
Old 04-13-14, 06:01 AM
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Check the rating on that sub panel ,where did the 50 Amp rating come from?
Just curious.
Geo
 
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Old 04-13-14, 06:58 AM
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sorry, all subs are rated at 125 amps. it is the feeder breaker that i was focused on (and the feeder wire size). below is a summary:
house main - 200 amp

poolhouse sub - 50 amp breaker in the main panel feeds the poolhouse sub with #4 copper

pool equipment sub - 30 amp breaker in the poolhouse sub feeds the pool equipment sub with #10 copper

separate sub - potentially for use with generator feeds #2 aluminum cable and terminates near the pool equipment area but i dont think i can use this for pool heater because of the bare ground and potentially because i cant have 2 subs at the pool equipment?
 
  #4  
Old 04-13-14, 09:42 AM
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Look's like the best plan would be to pull out the cable and reinstall single conductor #6 copper and a #10 insulated bond to a water tight 60 Amp disconnect to feed the heat pump which will have to be bonded to other equipment as per mfg. instructions ,I am not sure where the idea about not having the 2 sub panels came from,as always it may be best to run this by the AHJ

Have Fun and enjoy the heated pool!
Geo
 
  #5  
Old 04-13-14, 06:42 PM
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I thought there was some issue with 2 separate feeds to a single structure, and thought this May apply to pool equipment pad. If that is not the case, I think I'll drop another 50 amp sub panel from the sub in my basement (about 10 ft from main) to the equipment pad. Easier to dig than pull that aluminum out and ill also have a way to run generator power back to the main in the future (with transfer switch of course).

So to summarize if I do this: 200 amp main feeding a 125 amp sub panel in pool house which then feeds a 125 amp sub panel at the pool equipment for the pump and heater (50 and 30 amp breakers respectively). I will also have the 200 amp main feeding a 100 amp sub in the basement from which I'll feed a separate 100 amp sub panel at the pool equipment (50 amp breakers). So the pool equipment pad will have the 30 amps coming from the poolhouse sub and a 50 amp coming from the basement sub.

If all good, then should I have a separate grounding rod for the new panel or tie into the existing bonding on pool pump etc.

Thanks for the help and sorry for the long read - just trying to be comprehensive.
 
  #6  
Old 04-14-14, 04:08 PM
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Tooooo many sub panels, is this heat pump to heat the pool water? At any rate if I were doing this job I would be running a 50 amp circuit from the main panel to a 60 amp rain tight disconnect located at the heat pump if it is related to the pool then it will have to be bonded to the other pool equipment,just curious what size pipe is running from the pool house to the pool equipment and are you removing the propane heater?
 
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Old 04-14-14, 08:32 PM
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agreed, it sounds like a lot. especially if i add a 3 pole switch for a generator in the future - thus my posting here to figure out what people more knowledgeable would do. i prefer the raintight switch so that is what i'll probably do (any suggestions on which type appreciated).

i'll have to check the pipe size from the poolhouse sub to pool equipment sub but assuming it has room for lager wire, i dont think i can just run larger wire to power everything from the existing pool equipment sub as there is only #4 awg going form house to pool house.

not removing propane heater as it will be good for quick heating if needed (heat pumps take forever to heat) but it has very low draw.

if i do what you suggest, in the future i'd have:
main feeding poolhouse sub that then feeds pool equipment sub.
main feeding a combination sub/3 pole transfer switch next to the main for generator, and a 50 amp feeding the heat pump on a water tight disconnect (all bonded with other equipment)

sound like the right approach?
 
  #8  
Old 04-15-14, 06:06 PM
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Wire size

# 4 cu is rated for 85 amps (THHN) next size breaker is 90 amps so you would have 3 #4's and 1#8 bond ,pipe size I believe would need to be 1". I am curious about the heat pump taking for ever to heat the water,as far as I know the heat pump should be mantaining a temperature set point for the water my boss has one at that is how he uses his.
Geo
 
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Old 04-15-14, 07:00 PM
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i thought #4 was only good for 70 because i had to use the 60c column for the detached building (it's in 1.25 conduit).

re: the heat pump. it is at a weekend house so i would not keep it heated all week long.
 
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Old 04-16-14, 05:54 AM
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What article did you find the 60C rule? Makes sense on the weekend heat pump.
Geo
 
  #11  
Old 04-16-14, 08:02 AM
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i thought #4 was only good for 70 because i had to use the 60c column for the detached building (it's in 1.25 conduit).
Why did you not use the 75C column?
 
  #12  
Old 04-21-14, 07:10 AM
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Not sure where I read it but given that I can't find the reference now, I must have missread it. So if I can use the 4# up to a 90 amp breaker, I think the best route would be to put the feeder to the pool house on a 90 amp breaker, then Change the feeder write to the pool equipment to 6# and put in a 70 amp breaker. This would give me plenty of overhead.

Thanks for all the help on this.
 
  #13  
Old 04-21-14, 09:41 AM
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3#6's and 1#8 for the ground should be at least 1" pipe.
Keep us up on the project.
 
  #14  
Old 04-21-14, 12:32 PM
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I think it is schedule 40 but since it is in the wall I can only see the cross section coming into the panel . If schedule 40, can't I run 4 #6 which means 3 #6 and 1 #8 should be no problem?
 
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Old 04-21-14, 07:11 PM
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If schedule 40, can't I run 4 #6 which means 3 #6 and 1 #8 should be no problem?
That would work, but when they hot conductors are #6, all you need for the ground is a #10.
 
  #16  
Old 04-21-14, 07:34 PM
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interesting. if i go #10 wouldn't that limit my breaker to 60 amps? but my #6 on the feeder and neutral would allow for 65 amps which means i could go the next standard size up which would be 70 amp? i'm looking at table 250.122 for the ground sizing and 310.16 for the feeder sizing.

would love to pull #10 on the ground rather than #8 so please correct me where i'm misinterpreting.
 
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Old 04-21-14, 07:46 PM
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if i go #10 wouldn't that limit my breaker to 60 amps? but my #6 on the feeder and neutral would allow for 65 amps which means i could go the next standard size up which would be 70 amp? i'm looking at table 250.122 for the ground sizing and 310.16 for the feeder sizing.
Ok, I see your point. I was assuming you'd use a 60 amp breaker, but you can use a 70 amp breaker although it's rare to see #6s on a 70 amp breaker around here. Whether you use #8 or #10 for the ground might be a call for your inspector, I can see an argument for both sizes. Of course, to be sure, use the #8.
 
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Old 04-22-14, 05:03 AM
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Thanks. Figured the 70 amp would give me some headroom but your right I'll call the inspector.
 
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