Wiring a sub-panel

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  #1  
Old 06-18-04, 03:18 PM
Opto
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Wiring a sub-panel

Hi,

Iím wiring a new sub panel with 220. It will have a 50amp double pole GFCI breaker for a Jacuzzi and a 30amp double pole breaker for a dryer. Do I need to install an 80amp double pole breaker in the main panel to supply the sub-panel, or can I get away with less? How much less? Does it have to be a double pole breaker in the main panel?

Thanks,

Cliff
 
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  #2  
Old 06-18-04, 03:38 PM
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Join Date: Sep 2003
Location: Central New York State
Posts: 13,973
The breaker required is not the sum of the downstream breakers. It is the the appropriate size required to provide protection for the wire going to the subpanel. However, it must also be large enough to supply power for the lods you plan to run at one time.

What are the actual power requirements of the jacuzzi? What are the actual power requirements of the dryer?

Perhaps the most important question is, what is the distance from the main panel to the sub panel? If they are going to be right next to each other then run a larger breaker and use larger wire. The cost of the wire is not a factor at a short distance. If they are a good distance apart then the cost of the wire becomes a factor. However, it is not much ofn a factor when compared to the cost of the sub-panel and the breakers, especially the GFCI breaker.

I would run a larger breaker. You can then use the sub panel for future expansion. Why would you want to limit yourself to just those two devices?

The breaker at the main panel has to be a double pole breaker. How else would you get 240 volts?
 
  #3  
Old 06-18-04, 04:01 PM
Opto
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Iím working with an old Stablock main, limited slots, etc. The single pole question was dumb, but Iím trying to save slots.

An 80amp breaker will take up 4 Ė 1inch slots in the panel, where a 70amp will only use 2. There are only 8 - 1inch slots to begin with and I donít want to by 6 thin breakers if I donít have to.

The spa will pull about 36amps (except for the spike on start up). There is no dryer and wonít be one as long as Iím living in this rented house.

The sub panel will be next to the main. And the need for expansion is zero.

Thanks for such a quick reply.

Cliff
 
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