50 AMP Breaker on 8 Gauge wire

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  #1  
Old 04-28-14, 01:10 PM
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50 AMP Breaker on 8 Gauge wire

Hi Everyone,

I have a sub panel coming from my 200 amp service on the outside of my house. The main panel has a 30 amp breaker and then runs 8 gauge wire out to my sub panel. In my sub panel I have 2 at 20 amp by 2 pole breakers that power 1.5 hp pool pumps. Then a GFI breaker at 20 amps for the pool light. All of this is grounded as well. My question is, would it be possible to replace the sub panel with a larger panel so I can fit an additional 50 amp breaker for my pool heat pump. The pool heat pump is 37 amps min / 50 amps max. I am having an electrician out on Thursday but would like to educate myself in advance. I am very handy and do most things around the house myself including construction of my home, but when it comes to Electrical I am lost.

Thanks in advance for you help on this!
 
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Old 04-28-14, 01:13 PM
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#8 wire can supports total of 40 amps. It sounds like you need at least #6. It isn't the size or number of existing breakers that is important but the load on each breaker and if the load is continuous.
 
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Old 04-28-14, 02:56 PM
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You are going to need a larger feeder to the panel. You can install a larger panel, but do not have the capacity currently to run everything.
 
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Old 04-28-14, 04:16 PM
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That's what i was thinking. I do have some more info as well.

I am run in 2 1.5 hp pumps which draw continuous amps of around 9.3 and then the pool heat pump which will says 37 min/ 50 max. Since this is the case what do you guys recommend for a good setup? Of course considering potential pump replacement or heat pump replacement. Thanks!
 
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Old 04-28-14, 04:56 PM
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I would do at least a 70A feed. When I did my grandparents pool and hot tub, I used a 100A feed.
 
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Old 04-28-14, 05:21 PM
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So it seems I will be basically starting from scratch. I have an 80 ft run from the 200 amp service panel on the outside of my house. That panel then feeds another panel on the inside of my home.

Justin or anyone else, could you explain what is all needed to put in a 70 amp sub panel. This will really help me put things in perspective.
 
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Old 04-28-14, 08:36 PM
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Removing all the old equipment and installing new equipment pretty much.
 
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Old 04-29-14, 05:12 AM
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Basically you will have the same setup as now, but with a new larger feeder and panel.
 
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Old 04-29-14, 10:51 AM
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Ok, here is what I am thinking about doing. Let me know if this makes sense. Leave the existing sub-panel to power the pool light, pool pump, and waterfall pump. Then run a new 8/3 underground just under 80ft to a disconnect and then to my pool heat pump. This will allow me to keep the existing wiring and stay in code with a dedicated line with a disconnect. What are your thoughts on this?

If this fly's then instead of running 8/3 NM-B at 154.00. I would like to run individual strands. I assume this will save on cost, since it is a major influence here. Could you advise on what type of THHN or equivalent I should use. I read some the threads stating that the strands do not all have to be the same size. Could you tell me what gauge each of the wires would need to be including the copper? Also, what size conduit should I use, 1"?

Thanks!
 
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Old 04-29-14, 10:58 AM
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Has anyone done a demand load calculation to see if your service can support the additional load?
 
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Old 04-29-14, 11:10 AM
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Yes, an electrician came out a few days ago and said I have 70 amps remaining.
 
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