Largest Breaker

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Chuntly

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I have studied the code and am drawing a blank. What is the largest circuit breaker that can be installed in a 400 amp snap in service? (Service is Crouse Hinds). For instance, to install a sub panel in another part of the building.

I know the largest "readily" available breaker is 125 amp. But could one install a 200 amp breaker?

I have wondered for years and never could get an answer and cannot remember a specific section in the code that refers to this.

Thanks everyone!
 
This is not a code issue. The code does not care what size breakers you put into a panel, so long as they are consistent with what the manufacturer says the panel can handle. All the code cares about is that you don't overload the panel, and that you follow the manufacturer's instructions.

Welcome to the Forum.
 
Why not use 2 200 amp panels. Most 400 amp residential meter pans are duel lug.
Is it residential?

As far as the bonding of the panels it would be the same as one panel except you need to bond one panel to the other. Unless you use disconnects before the panels.
 
I don't know about Crouse Hinds, and I don't know if we are talking same scenario, but I just installed a Homeline 150a/2-pole breaker in a meter combo to feed a sub=panel. I could have gone 200 amp, but opted for the 150. This particular breaker takes up 4 spaces.
 
360Youth said:
. . . a Homeline 150a/2-pole breaker . . . takes up 4 spaces.
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Aye, and there's the rub. A 4-section 2-pole breaker expects that each pair of the two adjacent body pairs will be receiving power from the same phase.

Are there two or four output terminals? Two, I'll bet, because we can't split conductor strands into multiple lugs. That 4-section breaker isn't listed for branch-circuit use.

How would you connect the load wires? You'd have to alternate-wire four outputs (i.e., black/red/black/red) like two ajacent 2-pole breakers, if it were possible.
 
LarryFine said:
Aye, and there's the rub. A 4-section 2-pole breaker expects that each pair of the two adjacent body pairs will be receiving power from the same phase.

Are there two or four output terminals? Two, I'll bet, because we can't split conductor strands into multiple lugs. That 4-section breaker isn't listed for branch-circuit use.

How would you connect the load wires? You'd have to alternate-wire four outputs (i.e., black/red/black/red) like two ajacent 2-pole breakers, if it were possible.
Click to expand...

http://ecatalog.squared.com/pubs/Ci.../Accessories/HOM Sub-feed Lugs/0750DB0301.pdf

In this instance it had to be a right side busbar install because the wires only install from one direction and my feeder was exiting bottom right corner.
 
boboelectric said:
Sub feed 80% of main breaker rating.
Click to expand...

Is there a code reference for that? I'm pretty sure you can have 100%... at least it's not uncommon to see it.
 
360Youth said:
http://ecatalog.squared.com/pubs/Circuit%20Protection/Miniature%20Circuit%20Breakers/Homeline/Accessories/HOM%20Sub-feed%20Lugs/0750DB0301.pdf

In this instance it had to be a right side busbar install because the wires only install from one direction and my feeder was exiting bottom right corner.
Click to expand...
Looking at the pic, it's obvious that there are jumpers under all that extra plastic, which alternately join the four output terminals into two, A/B/A/B, similar to what I described above.

HOM1.jpg
 
LarryFine said:
Looking at the pic, it's obvious that there are jumpers under all that extra plastic, which alternately join the four output terminals into two, A/B/A/B, similar to what I described above.

HOM1.jpg
Click to expand...


What's the rub, bub? :grin: It is a two lug, 2-pole breaker fitting on 4 busbar stubs. Not the first 4 space 2-pole breaker I've installed, but I liked the design of the "bottom feed" lugs. I'm just thankful I did not need a left side mount because my wires would not have made the u-turn to tie into the lugs (POCO trough).
 
tallguy said:
Is there a code reference for that? I'm pretty sure you can have 100%... at least it's not uncommon to see it.
Click to expand...

Yes I would like some info on that aswell, I have always been a little cautious when sizing sub-panels simply because I cannot find a code article that directly or indirectly states what size sub-panels can be fed from a service panel.

I know all of the manufacturers have a max size branch circuit, and max size sub-feed breaker that is listed for each panel assembly, but aside from that I cannot seem to find anything in the NEC, call me dumb I guess :(.
 
360Youth said:
What's the rub, bub? :grin: It is a two lug, 2-pole breaker fitting on 4 busbar stubs.
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No rub a'tall. It just that the 4-section breakers I've seen, such as GE and Siemens, were used as main breakers. The two left sections both received power from one phase, and the two right sections received power from the other phase (A/A/B/B).

The four output terminals were similarly joined in adjacent pairs; the left two fed one bus, and the right two fed the other bus. To be supplied by a panel, the four sections would be fed from alternating buses (A/B/A/B/). This obviously would not work.

The four-section breaker and sub-feed that 360 linked to, and I posted pics of, are designed to accept power from alternating buses, and the plastic covering the output terminals must house the jumpers that convert four terminals (A/B/A/B) into two lugs (A/A/B/B).

Obviously, they consider single lugs not capable of supplying over 100a, so the purpose of the four-section breakers (both main and sub-feed types) is to parallel stabs for greater current-carrying capacity.

How many times have we seen failure of the 200a main breakers that stab onto the two top lugs in some panels? And it always seems to be the B-phase (lower or right) lug that melts away.


Added: It might be good to remember that we should probably not install any breakers opposite such large breakers or sub-feed devices, or at least check the panel documentation for such limitations.
 
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Larry ,,

Let me add this comment related to "" mega sized " breakers as i did see the photos of them and let you know that some of the breaker did actally make the housing little larger than noramally.

I allready did install the 150 amp subfeed breaker it is on the CH breaker panel and the main breaker of this panel is 200 amp but the info on the breaker door did stated can used large subfeed breaker but warn no other breaker across of it.

I should kept that dangbat instuction paper and scan it to you guys IRC that the instuction did forewarn about the buss connections and it did stated that no other breakers willbe on this area. so that mean the oppostie side of subfeed breaker have to be blanked or not used.

I found out that they have a bump build in so other breakers cant really lock in at all on that bussbar area.

just let you know head up with this

Merci , Marc
 
Kessler4130 said:
Yes I would like some info on that aswell, I have always been a little cautious when sizing sub-panels simply because I cannot find a code article that directly or indirectly states what size sub-panels can be fed from a service panel.

I know all of the manufacturers have a max size branch circuit, and max size sub-feed breaker that is listed for each panel assembly, but aside from that I cannot seem to find anything in the NEC, call me dumb I guess :(.
Click to expand...

408.36 Overcurrent Protection.
(A) Lighting and Appliance Branch-Circuit Panelboard Individually Protected. Each lighting and appliance branch-circuit panelboard shall be individually protected on the supply side by not more than two main circuit breakers or two sets of fuses having a combined rating not greater than that of the panelboard.
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You can go 100% of the rating of the panel. You must limit the continuous load to 80% of the overcurrent protection device, however. See 215.3
 
This is a 400 amp single phase service at a restaurant. Currently, there is 3 100 amp sub panels scattered about the building. There is no more breaker space. 1 of the 100 amp panels runs about 75 - 80%, the others draw hardly anything at all. All the large draws are in the main panel.

I would like to install an additional sub panel rated 200 amps 42 circuit REAL square D. My concern was installing a 200 amp breaker in this 400 amp panel. I intended on purchasing bolt on adapters for this particular Crouse Hinds panel and installing the breaker that way verses a 4 pole breaker as was spoken about earlier.

I'm very careful about loads... Just never installed a sub panel larger than 125 amps except in commercial buildings with bolt on or i-line breakers.

Thanks for the input guys!
 
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