AC Breaker - Bi-directional??????

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  #1  
Old 10-20-06, 03:56 PM
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Cool AC Breaker - Bi-directional??????

Are AC breakers bi-directional.
That is if power is feed in to the breaker through where the circuit is normally fastened and the current passed through to the lug strip, will the breaker function normally? That is kick if overloaded.
Looking for a 50 or 60 amp main breaker box and finding nothing lower than 125 AMP. Wanting to put a lower power panel with out having the cost of heavy wire. Don't need it. 50 or 60 AMps is more than required.
If the breaker would work bi-directional I would use a standard load center and fed the lug strips through a proper sized breaker. Waht the ability to cut power to the shop when not occupied.
 
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Old 10-20-06, 04:11 PM
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Originally Posted by Buster Brown
Are AC breakers bi-directional.
That is if power is feed in to the breaker through where the circuit is normally fastened and the current passed through to the lug strip, will the breaker function normally? That is kick if overloaded..
Yes

Originally Posted by Buster Brown
Looking for a 50 or 60 amp main breaker box and finding nothing lower than 125 AMP. Wanting to put a lower power panel with out having the cost of heavy wire. Don't need it. 50 or 60 AMps is more than required.
If the breaker would work bi-directional I would use a standard load center and fed the lug strips through a proper sized breaker. Waht the ability to cut power to the shop when not occupied.
Just use a 60 amp breaker at the source. You do not have to match the ampacity of the panel. You conductor must match the 60 amp breaker at the source. Most use a 4 conductor Al
SE cable rated at 60 amps or above.
 
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Old 10-20-06, 04:16 PM
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Yes, you can backfeed the breaker. Of course you need to check your local codes. Not sure where the NEC stands on this but I believe I have seen this suggested here by the experts for some purposes.
 
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Old 10-20-06, 04:26 PM
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If you're just putting on a subpanel in the same building, you don't need a main breaker at all, just main lug only. No need to backfeed!

And yes, breakers can be backfeed without any issues electrically. I don't think there are any NEC issues with it, either- some smaller panels are actually designed to be fed like this. The panel would have to be UL listed for that, is the only issue. Ask your city inspector if you plan to do this to make sure. Alternately, you could just put a big disconnect switch beside the panel, and run the power through that

Really, code is looking at the overcurrent protection for the cable- if you ran #10/3 romex to your panel, you could feed it from a 30A breaker and use a 125A main breaker if you wanted; the cable is protected by the feeder breaker, not the main breaker. In this case, the 125A breaker would just be acting as a switch and not an overcurrent protection device.
 
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Old 10-20-06, 06:05 PM
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I believe if you are going to use a breaker to be a disconnect and back feed, it must be bolted into the panel. It can't be the type just snap in.
 
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Old 10-20-06, 06:56 PM
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60 Amp breaker panel

If I could find a box that had the "bolt in" 60 amp breaker I wouldn't be asking if one could be "back fed" through a breaker acting as a "main". Have been looking and have given up. If one exists, no one can come up with the brand or source. I know it's not required, however I want the ability to kill the whole shop system in the shop if necessary. I just like safety. Over wire, under breaker. etc.
 
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Old 10-20-06, 07:33 PM
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> Most use a 4 conductor Al SE cable rated at 60 amps or above.

SE cable is illegal to use indoors. It's acceptable only when run directly from the meter to the first panel directly inside the wall. Some AHJs will only allow it to run up to 3-4'. For a panel-to-subpanel, though, SE is completely illegal.
 
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Old 10-20-06, 07:38 PM
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Yes, you can backfeed a breaker. I have a 100A CH sub-panel in my garage, and it is not a main lug panel. It was designed to be fed through a regular 100A breaker. No issues with doing it that way. Like someone else mentioned, make sure the breaker is screwed down.

Good Luck,
Joe Michel
 
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Old 10-20-06, 07:50 PM
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Since this is a separate building and numerous circuits, you will need a main breaker of some wort.

Just follow the advice given. Use the panel you have and make sure the breaker in the main panel is sized for the cable.
 
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Old 10-20-06, 07:52 PM
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NEC 408.36(F) does require a backfed breaker to be mounted with means other than just the snap in.

Some manufacturers make a locking accessory that does hold the breaker in. This would be acceptable for the purpose you have.

The last one I ran across was Square D.


Grover: you need to read NEC 338.10(B) (1) and (2)
 
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Old 10-20-06, 08:28 PM
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Originally Posted by grover
>
SE cable is illegal to use indoors. It's acceptable only when run directly from the meter to the first panel directly inside the wall. Some AHJs will only allow it to run up to 3-4'. For a panel-to-subpanel, though, SE is completely illegal.
Grover
Read Article 338 in the NEC and you will find approved uses for SE cable. One is for feeders for interior installations.
 
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Old 10-20-06, 09:20 PM
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Ah, you're right. I knew USE was illegal for interior use; I could have sworn SE was the same.
 
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Old 10-21-06, 06:30 AM
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NEC 2005, 408.36(F) allows back-fed plug-in breakers, but requires they be secured in place by an additional fastener that requires other than a pull to release.
 
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Old 10-21-06, 07:37 AM
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Originally Posted by grover
NEC 2005, 408.36(F) allows back-fed plug-in breakers, but requires they be secured in place by an additional fastener that requires other than a pull to release.
Not trying to be either mean or arrogant but I had posted this info as well as the SE info. My post was later followed by posts repeating what I had posted as if mine had not actually showed up on the forum.

Are my posts actually showing up??
 
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Old 10-21-06, 09:55 AM
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I read 338.10 after I read your post. Obviously didn't reread the thread this morning when I came accross 308.36(F) [was looking for something completely different] or I'd have noticed you had posted the same thing yesterday. Oops! (I left my copy of NEC at work and am stuck with just NFPA's preview at the moment which is annoying, or I'd have looked that up the first tiem I read your post and not have forgotten you posted it already!)
 
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Old 10-21-06, 10:07 AM
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Like I said, not trying to be mean or arrogant. It was as if nobody could read my posts.

Thanks. For a while I really believed it because nobody posted an answer to my question. It was just like talking to my wife.
 
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Old 10-21-06, 10:10 AM
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Ah, sorry! With quote & vb disabled, it's hard to direct replies. You and wareagle had both corrected my misconception about SE, and you had even included the relavant paragraphs in the code. (I reread the entire article anyhow, need to get up on this stuff!) I had intended that reply to be to both of you
 
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