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Old 06-02-2011, 12:09 PM   #106
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Do I need a sub panel here?


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Originally Posted by SD515 View Post
For your disconnect, you can have no more than 6 operations of the hand. If you’re going to have 7 or more breakers (including tandems) you’d have to use handle ties to bring those down to the 6 operations of the hand rule. Personally, I’d use a single breaker to act as the disconnect if 7 or more.
I'm not quite sure I understand you, but from what I'm gettin out of what you say here, I only have 3 circuits. Two 120 circuits and one 240 circuit (for the welder). I don't have 6 or more, so none of my breakers need to be tied together. Is this right?

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#2 aluminum is good for 100A only in 120/240V, 3-wire, single-phase dwellings, where it is either the service entrance conductors, or the main power feeder. In other words, all of the power for that dwelling has to run through that feeder, not just part of the building. 310.15 (B)(6)
Ok this is a shop, and this is the feeder. I need four wires. It is going to all of the building, not part of it. I interpret "part of it" to mean that the building would receive power in more than one place (which mine does not). Is this correct?

So I need a 90 amp breaker like I originally thought?


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Originally Posted by SD515 View Post
So in your case of only your shop being run off a feeder, you would use Tbl 310.16. Since most likely the terminals that this feeder is being hooked to are rated 75*C, the ampacity allowed for #2 AL is 90A if your running wire in conduit.
See my illustration here for a detailed idea of what I have.

You can see the main lugs in the sub panel which are not being used, and the "disconnect" breaker for the sub panel is backfed:


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Old 06-02-2011, 12:11 PM   #107
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Do I need a sub panel here?


I thought the 6 or less rule applied to the capacity of the panel, not the number of installed breakers. JS's panel has 8 slots.

Example: you could start with a 20 slot panel with 2-3 installed breakers and in the future add many more than the 6 or less rule allows.


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Old 06-02-2011, 12:35 PM   #108
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Do I need a sub panel here?


I can't find the code right now, but you need a min of 60 amp rated disconnect for any detached building.
This disconnect can be external to the building, or you can use the main breaker in the subpanel.
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Old 06-02-2011, 12:39 PM   #109
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Do I need a sub panel here?


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Originally Posted by rjniles View Post
I thought the 6 or less rule applied to the capacity of the panel, not the number of installed breakers. JS's panel has 8 slots.

Example: you could start with a 20 slot panel with 2-3 installed breakers and in the future add many more than the 6 or less rule allows.
I don't see where the code talks about the capacity of the panel in this regards. As your example of a 20 slot panel....you could have all 20 slots filled with breakers, and have handle ties on them. As long as no more than 6 operations of the hand are required to shut them off, you're code. Good luck finding such identified handle ties though. No-one, including the code, can predict the future. As long as it's installed poperly now, it's good. If in the future, something is changed that will require more than the '6 operations of the hand' rule, it would have to be dealt with then.
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Old 06-02-2011, 12:42 PM   #110
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Do I need a sub panel here?


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Originally Posted by jbfan View Post
I can't find the code right now, but you need a min of 60 amp rated disconnect for any detached building.
This disconnect can be external to the building, or you can use the main breaker in the subpanel.
Are you thinking 225.39/230.79?
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Old 06-02-2011, 12:47 PM   #111
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Do I need a sub panel here?


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Are you thinking 225.39/230.79?
That looks like the ones I was thinking about.
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Old 06-02-2011, 01:10 PM   #112
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Do I need a sub panel here?


Quote:
Originally Posted by J S Machine View Post
I'm not quite sure I understand you, but from what I'm gettin out of what you say here, I only have 3 circuits. Two 120 circuits and one 240 circuit (for the welder). I don't have 6 or more, so none of my breakers need to be tied together. Is this right?
Let's see if we can clear this up...

A panel without a 'main disconnect' in it to kill the busbars...
2 single pole breakers + 1 two pole breaker=3 operations of the hand to shut off the circuits in that structure. You don't need any additional handle ties.

A panel with a 'main disconnect' in it to kill the busbars...
1 two pole breaker=1 operation of the hand to shut off the circuits in that structure.

Both are code compliant. The key is 'no more than 6 operations of the hand' to shut off all the circuits in that structure. When you have 7 or more breakers, many times it's easier to use a single breaker to shut the panel off.
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Old 06-02-2011, 01:17 PM   #113
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Do I need a sub panel here?


Quote:
Originally Posted by SD515 View Post
Let's see if we can clear this up...

A panel without a 'main disconnect' in it to kill the busbars...
2 single pole breakers + 1 two pole breaker=3 operations of the hand to shut off the circuits in that structure. You don't need any additional handle ties.

A panel with a 'main disconnect' in it to kill the busbars...
1 two pole breaker=1 operation of the hand to shut off the circuits in that structure.

Both are code compliant. The key is 'no more than 6 operations of the hand' to shut off all the circuits in that structure. When you have 7 or more breakers, many times it's easier to use a single breaker to shut the panel off.
I see now. Interesting way the code looks at it, that's for sure. I am I the forst one who has ever been confused by what the code says? I can't tell you how many times I have read and reread passages and places in the code, and still have trouble understanding it.

So basically if I run my lines directly to the lugs it will be good to go, and if I want to add a breaker there to serve as a disconnect I can do so if want. Both of these choices would be code compliant.
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Old 06-02-2011, 01:20 PM   #114
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Do I need a sub panel here?


Quote:
Originally Posted by J S Machine View Post
Ok this is a shop, and this is the feeder. I need four wires. It is going to all of the building, not part of it. I interpret "part of it" to mean that the building would receive power in more than one place (which mine does not). Is this correct?
No, your feeder does not supply the entire dwelling (house, outbuildings, etc). What I was trying to say is it only supplies an outbuilding, therefore #2 AL ampacity comes from Tbl 310.16, not 310.15(B)(6). Which is where your electrician was probably thinking.

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So I need a 90 amp breaker like I originally thought?
Yes, in your main panel, where your feeder is originating.
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Old 06-02-2011, 01:27 PM   #115
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Do I need a sub panel here?


Quote:
Originally Posted by J S Machine View Post
I see now. Interesting way the code looks at it, that's for sure. I am I the forst one who has ever been confused by what the code says? I can't tell you how many times I have read and reread passages and places in the code, and still have trouble understanding it.
Ain't that the truth !!


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Originally Posted by J S Machine View Post
So basically if I run my lines directly to the lugs it will be good to go, and if I want to add a breaker there to serve as a disconnect I can do so if want. Both of these choices would be code compliant.
Yes, with the info you provided about 2-1 pole breakers + 1-2 pole breaker. If you ever think you'll be adding to that panel, I'd consider using a 'main disco' breaker now, and not the lugs. At least keep the feeder wires long enough to land on a breaker later.
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Old 06-02-2011, 01:48 PM   #116
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Do I need a sub panel here?


Ok. Thanks for the tip on the extra wire. I had thought about that, and I was trying to think of a way to do it. The electrician will be hooking it up so I'll be sure to bring that up. No more wire than there will be in the box, it should not be a problem if those mains are a little long.

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