Main panel tie in for sub panel??

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  #1  
Old 01-01-14, 05:06 PM
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Main panel tie in for sub panel??

Hello al. Hope this finds you well.

I need to wire up a 150A sub panel. I will be using 1/0 to connect it and understand how to wire in the sub panel.
My question is concerning the tie in to the main panel. The sub panel has a main breaker at the top. I understand that I will also have to remove the tie bar.

The only info I have found to tie into the Main Panel is by using a 150A breaker in the Main Panel. It seems quite redundant. And the cheapest I found was about $78 for a loan center breaker (to be used in the main panel). Is this the only way that I can tie in to the main panel?

Here is what I found at Depot for the loan center breaker: Square D by Schneider Electric 150 Amp Double-Pole Main Circuit Breaker for QO and Homeline Load Centers-QOM2150VH at The Home Depot
 
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  #2  
Old 01-01-14, 05:50 PM
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The sub panel has a main breaker at the top. I understand that I will also have to remove the tie bar.
I'm not sure what you are saying/asking but the main breaker is used as a disconnect in the subpanel if the subpanel has spaces for more then six circuits. The neutral bar must be isolated from the subpanel, usually by removing a green screw (or not installing the screw) or in rare cases by removing a strap.

The only info I have found to tie into the Main Panel is by using a 150A breaker in the Main Panel. It seems quite redundant.
Not redundant, it protects the cable to the subpanel and the subpanel.

What is a:
I found was about $78 for a loan center breaker
What load will be on the subpanel? Just because the subpanel is 150 amps doesn't mean it needs a 150 amp feed. You could feed a small house with 100 amps or a shop with 60 amps. Tell us what you are doing and we can better help you.
 
  #3  
Old 01-01-14, 07:02 PM
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I will be setting up a tshirt business in an attached garage and my basement.

I bought this panel: SQUARE D Load Center,150 A - Panel Boards - 5F694|QO130M150 - Grainger Industrial Supply

I meant that since the sub panel will have a 150A main breaker at the top of the sub panel, will I need to also have a 150A breaker in the main panel like this Square D by Schneider Electric 150 Amp Double-Pole Main Circuit Breaker for QO and Homeline Load Centers-QOM2150VH at The Home Depot OR can I wire it {safely} like this: http://www.nachi.org/forum/attachmen...3-9-07-060.jpg

I read an article here: How to Install a Subpanel > Handyman Club of America which said: In most main panels you’ll find that the neutral bus bars (the common bars that are isolated from the panel case) are connected via a metal tie bar. In a subpanel, however, the neutral has to be totally isolated from the ground, so you must remove this tie bar.
 
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Old 01-01-14, 07:29 PM
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Just because you chose a 150A sub panel, doesn't mean you need to feed it with a 150A breaker nor 1/0 wire. If you wanted, you could feed it with 10/3 w/ground cable and a 30A breaker. Or a 60A breaker and corresponding wire. Or a 100A breaker and the correct size wire.

You always need the correctly sized breaker (based on wire size) in your main panel. The link you provided was not the correct breaker type. You need a double-pole breaker that will fit either your QO or Homeline panel (assuming you have a Square D main panel). (You may have trouble finding over a 100A breaker, I'm not sure if they make them over 100A)

If your subpanel is in the same building, you don't technically need a main breaker in that panel, but since you already have the panel, there's no harm in using it.
 
  #5  
Old 01-01-14, 08:04 PM
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batcave, I think that there's some terminology issues in your second post.

the main switch cuts off all power to the panel in which it is located.

a breaker cuts off power to the circuit that it feeds from a given panel.

If you have a circuit breaker in your main panel, you do not necessarily need to have a main switch in your subpanel. neither of my subpanels have main switches in them.

I can't deny that it appeals, having a main switch in the subpanel, only because it's mildly inconvenient to go shut off the subpanel's breaker in the main panel, but it's not something that's been enough of a problem to compel me to replace the subpanels in order to gain that feature.
 
  #6  
Old 01-01-14, 08:09 PM
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Yeah, that is all I could find. I thought it looked odd.

So, if they don't make them for that size amps... how do I connect it in the main panel?

Can I wire it like this: http://www.nachi.org/forum/attachmen...3-9-07-060.jpg I found that picture at a site here: Sub panel tie in - InterNACHI Inspection Forum

All in all, with everything that will be on the sub panel.... it will need the entire panel. The house doesn't require much (gas heat).
 
  #7  
Old 01-01-14, 08:25 PM
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As both Zorfdt and I have written you do not need a 150 amp breaker to supply a 150 amp panel unless your load at any given time will approach or exceed 100 amps. First tell us the actual loads in amp or watts of the equipment that you will be using and we can go from there. We also need to know the size of your main panel. Is it at least 200 amps?
 
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Old 01-02-14, 12:46 AM
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In order to use that alternate method you would have to first have "feed-through" lugs on the service (main) panel and I can almost guarantee that you do not have these lugs. Secondly, unless you can utilize the "tap" rules (either ten or twenty five feet total wire length from one panel to the other depending on several other conditions) the wiring from feed-through lugs must be of sufficient size that it is protected by the main circuit breaker in the service panel

If the sub-panel is in the same building as the service panel then the sub-panel does NOT require a main circuit breaker, regardless of how many individual circuit breakers are in the sub-panel. You DO need a four-wire feed to the sub-panel.

You need to specify the manufacturer and model of the service panel Circuit breakers are NOT interchangeable even though they may physically fit several different makes/models of panels. Finding a 150 ampere CB that will fit a 200 Ampere panel may be a challenge or even impossible depending on the panel itself.
 
  #9  
Old 01-02-14, 05:29 AM
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Many panels have a bus stab rating that will not allow a breaker that large to be installed.
 
  #10  
Old 01-02-14, 09:03 AM
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All in all, with everything that will be on the sub panel.... it will need the entire panel. The house doesn't require much (gas heat).
What is the load you'll be adding to the subpanel?

The 150 amp breaker you linked to is a replacement main breaker and won't work as a branch breaker.
 
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