Is there a limit to # of breakers?

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Old 07-18-05, 08:25 PM
mxw128
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Cool Is there a limit to # of breakers?

I have a newer house (2 years or so old) and have a single Cutler Hammer panel with 200 amp service. I am in the the process of finishing the basmment and adding a hot tub. I was reading the label on the inside of the cover and it said "Max sum of breakers per stab is 200A" There are a total of 32 slots for breakers in the panel (2 columns or sides of 16 each) and 24 of them are used (various 15 to 40 amp breakers). What is a stab?? When I add up the vaules for each breaker, I get 200 for each side. Did the builder leave me with no expandability in the panel? (even through there are 8 empty circuits left?
 
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Old 07-18-05, 08:44 PM
Eggroll
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code says 42 circuits per enclosure.

So... even though your panel is made for 32 circuits... depending on the style you can get what some call "split" breakers. Your panel probably has 1" breakers in it, and they make one that's the same size, but has two breakers inside. It also has 2 lugs for two different hot wires. Those breakers should be available anywhere breakers for your panel are sold.

Even though the amp ratings for the breakers add up to 200 per leg (side), it doesn't necessarily mean that your house is pulling the full 200 amps on each leg. Most of the 20 amp circuits will rarely pull the full 20 amps. They're just 20 amp breakers because that's what the wire connected to the breaker is good for.
 
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Old 07-18-05, 08:46 PM
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A stab is a point on the hot buss where the breakers connect.

Adding the breaker rating together does nothing. Often times you will have 400 amps of breaker rating loads on a 200 amp panel.

As far as expandability the only way is to perform a load calculation. The formulas are in the Code book.
 
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Old 07-18-05, 08:51 PM
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As far as Eggrolls comment about the 42 per enclosure. That is the maximum for a lighting and appliance panel. This will NOT override the manufacturers listing requirements. If your panel label says 32 circuits max. that is all that are allowed. A 2 pole breaker counts as 2, single poles count as 1.
 
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Old 07-19-05, 09:24 AM
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Originally Posted by Eggroll
code says 42 circuits per enclosure.

So... even though your panel is made for 32 circuits... depending on the style you can get what some call "split" breakers. Your panel probably has 1" breakers in it, and they make one that's the same size, but has two breakers inside. It also has 2 lugs for two different hot wires. Those breakers should be available anywhere breakers for your panel are sold.

Even though the amp ratings for the breakers add up to 200 per leg (side), it doesn't necessarily mean that your house is pulling the full 200 amps on each leg. Most of the 20 amp circuits will rarely pull the full 20 amps. They're just 20 amp breakers because that's what the wire connected to the breaker is good for.

I'll also second what eggroll said. I too was under the impression when I first ventured into the electrical world years ago that by adding up all the breakers values they were supposed to stay under the main breaker value, usually like 200A. heh, whenever you purchase the proper tools for various jobs you quickly learn how things work in these regards.

For example, even though your panel already has breakers exceeding the main breaker rating, you might be interested in seeing just how much current you draw at any given time. I would suggest you purchase an amp meter and then clamp that on to your main incoming service wire and then turn on various appliances in the house. In my house, which is about 2800 sq. ft., with just the lights, the computers and maybe a tv on, the total draw is maybe 3-4A...at the most, 5A. When my 5ton A/C kicks on, the total current jumps to around 27A.

Instead of looking at breakers in terms of total amp value, it's probably more accurate to look at them as "oh, a #12 wire is attached to this breaker" instead.

#14 wire = 15A
#12 wire = 20A
#10 wire = 30A
 
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Old 07-19-05, 01:02 PM
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Originally Posted by mxw128
I was reading the label on the inside of the cover and it said "Max sum of breakers per stab is 200A"...What is a stab??
That means that the sum of breakers directly across from each other in the panel cannot be greater than 200A. This would only be possible if your panel was serving 2 large subpanels and had, for example, a 100A and 150A breaker in slots 1,2,3, & 4. Other huge loads like electric heat or on-demand water heaters also could use >100A breakers. I doubt you have any though.

My initial reaction is that you have plenty of extra capacity in your 200A panel. You could be closer to the limit if you have electric heat, electric hot water, electric cloths dryer, and electric cooktop, but still I bet you have capacity for the hot tub.
 
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Old 07-19-05, 08:03 PM
mxw128
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Thanks for the quick responses!!!

Thanks to all for the quick resaponses. Yeah, adding up the breakers didn't make much sense to me but that statement inside the cover got me wrapped around the axle. Besides a couple of A/C units (30 and 40 amp) , there really isn't much in there, so I thought I would be OK. Thanks for the help! (Now I know where to come with the questions!!! ) Speaking of which:

Is there any disadvantage to using the "Slim" or "half-height" breakers? I don't see the point of adding a subpanel if I can stretch the 8 remaining slots for my basement using them.. (6 left after the hottub)
 
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Old 07-19-05, 08:15 PM
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If your panel allows tandem breakers (and not all do), then this would be the first choice for adding more circuits. But you still have 8 unused spaces, so you don't need them yet unless you're adding more than 8 circuits.
 
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